May 26, 2022 • 50 mins
A postdoctoral researcher at Perimeter Institute, Meenu Kumari is an explorer at the edge of quantum science. Her research explores open questions at the meeting points of quantum information, quantum foundations, and quantum matter. In this conversation with Lauren and Colin, she explains what it means to study the realm where quantum meets classical, and how we might harness the peculiar nature of the quantum realm to better understand chaos. She shares her unlikely path toward theoretical physics from a childhood in India, where she had to overcome social pressures and doubters to pursue an early love of science. View the episode transcript here.
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Conversations at the Perimeter is co-hosted by Perimeter Teaching Faculty member Lauren Hayward and journalist-turned-science communicator Colin Hunter. In each episode, they chat with a guest scientist about their research, their motivations, the challenges they encounter, and the drive that keeps them searching for answers.
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Episode Transcript
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(00:00):
(soft music)
(00:09):
- Hi everyone.
And welcome back toConversations at the Perimeter.
I'm Lauren.
- And I'm Colin.
- And today we're bringing you
a conversation with Meenu Kumari,
a postdoctoral researcherhere at Perimeter Institute
who specializes in quantum chaos.
- Quantum chaos.
You know, that's a term
that I actually haven't encountered before
our conversation with Meenu,
(00:30):
despite talking to a lotof theoretical physicists,
that, that idea of quantumchaos was, was new to me.
And I was fascinated tohear about it because
when I first heard it, honestly,
it sounds a bit like somethingoutta science fiction.
- Well, Meenu has actuallybeen a friend of mine
for many years now,
but I still learned a lotfrom this conversation
about her life, her journeyto where she is today
(00:50):
and her research in the quantumto classical correspondence
and really studying how we can move
between these quantumand classical realms.
So without further ado,
let's dive right into the quantum chaos.
- Meenu Kumari.
Thank you so much for joiningus here at Perimeter Institute
(01:10):
in our, in our beautifulbut empty theater.
Thanks for joining us.
- Thanks a lot for having me.
- So Meenu, thank you so much
for sitting down with us today.
I'm really excited to talk to you.
Maybe you can just start bytelling us what you do here
at Perimeter, what your role is,
and also what you'reinterested in studying.
- I'm a postdoc in the quantuminformation research group
(01:31):
at Perimeter.
I joined in September, 2019,
and I did my PhD at IQC atthe University of Waterloo
from September, 2014 to August, 2019.
- So IQC, that's the Institutefor quantum computing,
just down the road from here.
So is quantum computingpart of, of what you do?
(01:54):
You're a theorist.- Yeah.
- And quantum computingsounds like it's for machines.
So can you explain
how you're connected to quantum computing?
- My field,
my research is in the fieldof quantum information,
using the tools and techniquesof quantum information
to study other questions in physics.
The thing is
(02:15):
quantum computing uses
quantum information techniques
or for quantum processing techniques
to build like quantum computer,
like so many tools
and techniques have been developed
in the field of quantum information,
which can be used
in other fields of physics,
like high energy physics,
or (mumbles) metaphysics
(02:37):
to study other questions.
So quantum information is basically
like
world is fundamentally quantum, right?
If you--- Oh, so,
just to interrupt the worldis fundamentally quantum
in the sense that
at the underneath everything,
quantum mechanics sort of describes how,
how the world works at this small level.
If you dig deep enough into anything
(02:57):
you'll get into the quantum realm.
Is that fair?
- Yeah.
So the thing is like
first classical physics was developed,
which is like Newtonian mechanics,
Galilean relativity
and then Hamiltonian mechanics and so on.
So those theories describe the world
at the macroscopic level
(03:18):
very well, actually.
But towards the end of 18th century,
like around 1890 or something,
there were so many phenomena that,
that we are discoveredexperimentally, which,
which were not,
which the physicistswere not able to explain
using the Mecca,
using the formulationof classical physics.
So they started to diginto what's going on,
(03:39):
trying to understand, for example,
for the photo electric effect.
Around 1920 to 1930,
this new formalism of quantummechanics was developed.
And over the years,
we have seen that
whatever we can predict
from the theory of quantum mechanics,
most of the experiments that we do today,
the results of those experiments can be
(04:01):
explained using the theoryof quantum mechanics.
So that's the thing that theworld is fundamentally quantum
because almost all the experiments
at the microscopic level,
or at atomic level basically,
can be explained using the,
using the theory of quantum mechanics.
Although the formulationof quantum mechanics is,
is quite non-intuitive.
- So I have a question there.- Yeah.
(04:22):
- So as you started to allude to,
there's so many researchfields that people work in now
that are studying differentquantum properties of matter.
So you mentioned quantuminformation, quantum computing,
there's also quantummatter, quantum foundations,
quantum field theory.
There's probably a lot of other fields
that have the word quantum in them.
So can you just tell us a little bit
(04:44):
about that word "quantum"
and really what are someof those quantum features
that are so interesting
and confusing as opposed to
the features we might be moreused to in classical matter?
- Yeah.
So two of the most intriguing features
are the principle of superposition
and the principle ofentanglement actually,
Schrodinger's cat is a famous example.
(05:06):
Unless until you look at it,
you don't know whetherthe cat is dead or alive.
So.
- I'm, this is,
this is the famous thoughtexperiment with the cat in a box.
And it's a,
it's a sort of metaphor for things
that can be in one stateor another at the same time
until they're measured.
So you don't know if this cat.
- Yeah.
- I, when I was younger,
I thought that was a real cat
(05:26):
in a real box and a real experiment.
I'm glad to know it's not.
(laughs)
So that explains superposition,
this idea of things in the quantum world
being in a state that'smore than one thing.
- Yes.- At the same time.
- Yeah, that's right.
So for example, if youtake a quantum coin,
a classical coin is eitherin the state of heads,
(05:47):
like if you flip it, itis either heads or tails,
but quantum coin can bein a superposed state of
heads and tails,
and then you measure it
and you will get either heads or tails
out of your measurement result.
By measuring it again and again,
you will find probabilities
of getting heads as well as tail
(06:08):
and using that, you canconstruct the quantum state.
So the quantum coin is basicallyin a superposition state.
It is not just only in heads
or in tails.
Like quantum mechanicsisn't a simple theory.
It's not,
it doesn't describe one single instance
of a particle or something.
(06:29):
Like it describes,
like if you do something
over and over many times,
what will be the output that you'll get,
like what will be theprobability of getting.
- It works more in likelihood
and probability than an exact prediction.
- Yeah, that's right.
So if you just measure it once
and see whether it is tail, heads,
you can't really say that it,
(06:50):
whether it is in thesuperposition state of heads
plus tail, or whether it is really heads,
you will have to perform
the measurement on the same copy,
on the multiple copiesof the same quantum state
again and again to figure out whether
it is in a superposition state or not.
- This is part of whatconfuses a lot of people
about quantum mechanics, right?
(07:11):
This is 'cause we don't experience that.
When we flip a coin, it'salways heads or tails.
- Yeah, that's right.
- Cause it's a, it's a macro world coin.
So it's okay that peopleare confused by this, right?
It's not something we experience.
- Yeah.
It is very non-intuitive,
like we don't really observe anything
in a superposition state.
So that's where quantumfoundations come in.
(07:33):
We describe
a quantum particle
using a wave function,
which can be in a superposition state,
but we don't reallyobserve that wave function.
What we observe is
probabilities of certainkinds of observables,
like any real observable,for example, for,
with this coin,
when you measure it in the basis of head,
(07:54):
head and tail, when you measure it,
whether you'll get heador a tail, actually.
So quantum foundation is like
trying to understand what is real
versus what we infer out of measurement.
So this whole (mumbles)mathematical formalism
of wave function
is a mathematical construct
(08:15):
because we can't see the wavefunction (mumbles), right.
That the quantum particleis indeed in that state.
We can only infer observables,
measurements of observables actually.
- Right.
- So quantum foundations deals with
trying to understand what is real
versus what we can observe.
(08:36):
Like what is the connectionbetween those two.
- And I just wanna goback to something you,
a word that you said a few sentences back,
you were talking about
trying to measure these quantum states.
And you've talked about doing that
on many copies of the same state,
but I think that word copy
is maybe something we should talk about
because I think there'sanother interesting property
(08:57):
in quantum mechanics,
but you can't actually
make an exact copy of a state.
Is that right?
- You can,
you can't make an exact copyof an unknown quantum state.
So that's no cloning theorem actually.
Like once you know what is thequantum state mathematically,
you can prepare many copies of it.
But if you don't know
(09:17):
what is the quantum state of a particle,
you can't copy it.
And that is a principle that is,
that would be used in manydifferent types of applications
of quantum information
and quantum computing,
actually like quantum cryptography.
- And that's different thanin classical cryptography.
Is that right?
- Yeah.
Like you can create copiesof something basically
(09:37):
in quantum, classical cryptography
without other peopleknowing about it actually.
But quantum state,
like as soon as you measure,
the quantum state of particleis destroyed actually.
So once it is destroyed, the other,
the receiver end will know
that
it has been intercepted by,
(09:59):
by some Eve actually.
- Is that the quantum cryptography
or the idea of quantum encryption
that measuring a quantum state changes it
and therefore you can detectwhether it's been measured?
- Yeah, that's right.
- So, and that's a,
that's sort of a branchof quantum computing
and quantum information.
I wanted to get back to that
'cause you said you workat these intersections
(10:21):
of quantum information,
which is related to quantum computers,
which are in theory,
these very powerful computersthat harness superposition.
And, but you said you'reat the intersections
of quantum computingand quantum foundations.
So which questions are currently sort of
the focus of your attention?
What are you trying to figure out?
- I became interested in,
(10:44):
in chaos actually.
So initially I did a few projects in my,
during my undergrad studies
in the field of classical chaos.
And then I did a project
in the field of quantum chaos.
- So can you actually just start
by telling us what classicalchaos is maybe before we,
I know that's not really what you work in,
(11:05):
but it might be useful to start there.
- Chaos is a pretty loadedterm, non scientifically,
but chaos is a veryspecific meaning in your.
- Many people would be familiar
with the term butterfly effect.
So it is like if,
can the flap of a,
of the wings of a butterfly
in Brazil cause a tornado say in Germany.
(11:27):
So that's the butterfly effect,
can very small changesin the initial conditions
lead to vast differences in the outcome.
Chaos is basically unpredictability due to
sensitivity to initial conditions.
Like the seeds of chaos theory
were sewn by Henri Poincare,
but then it was well formulated
(11:47):
by a meteorologist, EdwardLorentz, around 1960s,
had built a weather model and.
- Sorry, a meteorologistcame up with chaos theory?
- Yeah.- Okay.
I didn't know.
Is weather and meteorology is that,
that's classical chaos theory,
that has nothing to do with quantum.
- Chaos is basically a property
of classical dynamicalsystems, not just physics,
(12:11):
like any kind of dynamicalsystems you want to predict.
Like for example,
the population of fish in a pond
or weather is another example.
And then even in stock marketor something like that,
chaos has applications in every,
so many fields actually.
So dynamical system is basically
any system that evolves with time.
- Sorry, you said a,
(12:31):
a dynamical system.- Dynamical system.
It's any system that evolves with time.
And so you basically haveeither differential equations,
like you have a set ofvariables, for example,
for whether you can havevariables as temperature,
pressure or something like that.
And differential equations
telling us how thoseevolve with time basically.
(12:53):
So now these differential equations,
if they are nonlinear,
if they nonlinearly dependon the other variables,
then it results in.
- Maybe I'll, I'll just ask a question
to make sure I'm understanding.
You're saying that, you know,weather can be an example.
So is this why I mightsometimes look at my phone
and see that it'ssupposed to rain tomorrow,
(13:14):
but then it doesn't actually rain.
Is that, is that because
it's very difficult to predict,
is that related to the factthat it's a chaotic system?
- The weather is a chaotic system.
That's right.
So the thing is like,
we all know that we can'treally predict the weather
of any place.
Like for example,
if we look at the weatherof Waterloo today,
how is it going to betomorrow or day after?
(13:36):
And we see that many times,
it's not the same as whatit is tomorrow, right?
So why is that the case?
We have advanced technologically so much,
but still we can't reallypredict the weather
a few days in advance of any place.
If we had predicted,
like if we could havepredicted so many catastrophes
(13:59):
and on earth would have been,
could have been like avoided,
or not avoided,
the destruction could have been avoided.
- Yeah, if you knew a hurricane was coming
a month in advance,rather than a few days.
- Yeah.- In advance,
you'd be.- Something like that.
- You'd be grateful for chaos theory.
(laughs)
- But the thing is
they are predicted onlya few days in advance
with some probabilitythat this could happen.
(14:20):
So it is because likethese models are nonlinear,
so they can't be solved exactly.
And they can exhibit chaos that
whatever initial condition we input,
for example, the temperature or pressure,
whatever we input in,
in the bunch of,
for the variables in the bunchof differential equations,
those variables will havesome error in the last visit.
(14:44):
Like if we have five visit (mumbles)
in our value of the temperature,
there is a small error in the fifth visit
after the decimal, right?
So that very small error
in the last visit
actually can amplify
upon evolution of the system.
- Right.
- The more precise weare in the initial value.
(15:07):
- String of digits after the decimal.
- Yeah.- Is.
- The longer we canactually predict the weather
to the likelihood ofthe weather in advance,
but it will lead tounpredictability after some time,
no matter how much precision you're given,
there is going to be some error in the end
and that will lead tounpredictability in the long term.
(15:31):
So that's why weather isan unpredictable system.
But that's the thing.
Weather is a very complex model
and it may look like chaos is a property
of very complex models,
but that's not true.
Even very, very simple systems,
for example, double pendulum, is chaotic.
So double pendulum is basically like
you have some simple pendulum
in which you have a bob
(15:51):
attached to like some knob,
which oscillates in a plane.
Now you attach one more bobto the end of the first bob.
- So I have kind of a,
a stick or somethingwith a ball on the end.
And then I have another.- Yeah.
- Rod attached to that withanother ball on the end.
- Yeah.- And it can swing
(16:12):
independently of the first, right?
The first ball can swing,
would not independently but affected by.
- They will be dependent in some way,
but overall the motion is chaotic actually
like you can search variousYouTube videos actually that.
- They're really fun to watchby the way, double pendulums.
- Yeah.
- Good hypnotic entertainment.
(16:32):
- Very small initial condition change
can lead to highunpredictability actually.
So that's the thing,
that chaos is not just aproperty of complex systems,
but very, very simplesystems can exhibit chaos.
- Interesting.- So I,
I wanna ask something herejust to make sure I understand.
So you're saying with weather,
if I'm say measuring the temperature,
(16:53):
it might be, say 20 degrees Celsius,
but I'm not sure if it's 20 degrees
or 20.0001 degree Celsius.
This seems like a very small change.
And if it was a non chaotic system,
maybe the result two days later
wouldn't depend so much onwhether it was 20 degrees Celsius
or 20.0001.
But because it's such a complicated system
(17:15):
that's non-linear
and we call it chaotic,
it's in the end gonna depend a lot
on that really smalldifference in that variable.
Is that correct?
- Yeah, that's right.
So that small differencein nonlinear systems
put in principle amplifyto very large differences
in an unpredictable manner.
(17:35):
But if it is a linear system
or if it is an integrableor regular system,
like different words for the same time,
then those small differenceswon't amplify a lot actually,
or it'll amplify a verypredictable manner.
- I see.- If it'll amplify,
like there can be unstableboundary systems in ways,
things can amplify, but westill know how it amplifies.
(17:59):
So.- So,
may I jump in?
A quantum system,
is that more complex orless complex than weather?
Quantum being very small and,
and there's parameters around it.
What does quantum chaos refer to?
- Quantum chaos has not beenvery well understood yet.
Although it's been like a hundred years
(18:20):
of the development of quantum theory
and why is quantum chaos
and quantum classical correspondence
is an important problem.
I'll like to give another example.
For example, Galileanrelativity was well known from
a few centuries, right?
And then came in a specialtheory of relativity
where the speed of the objectcan be very, very high.
(18:44):
Now, as you start reducingthe speed of the object
towards normal speed,
special theory of relativity,
very smoothly merges intoGalilean theory of relativity.
It's not like Galilean theoryof relativity is wrong, right?
It is still right at the level
we observe our everyday world.
Then this new theory of,
(19:04):
this new theory of relativity was formed.
- By Einstein is?
- Yeah.- Okay.
- That's right.- I got that one right.
(laughs)
- And then it smoothlymerged with the old theory
where the old theory waspredicting things very well
in normal circumstances,
which we can observe through our eyes.
Likewise, classical physics is very,
(19:27):
can't very well predict our everyday world
that we see around
most of the things.
And then quantum theory
is something that describes phenomena.
The microscopic level
are at levels, which is,
does not happen in normal
or circumstance in forexample, very low temperatures,
chem temperatures near zeroKelvin or something like that.
(19:49):
We don't really see that.
So for example, super conductivity.
So you can see defectivesuper conductivity
at a macroscopic level.
It's a big object visibleto our eyes, right.
And we see that, but we can't ex--
- A levitating super magnetictrain or something like that.
- Yeah, that's right.
So,
so that happens at very,very small temperatures,
(20:11):
although it is macroscopic,
but quantum mechanics isthe thing that predicts it
where a thing is there,
there has to be somethingdifferent from normal circumstance
where classical physics fails,
for example, very,
very low temperature or very,
or microscopic scale
in terms of like size of anobject or something like that.
(20:33):
So quantum theory explainsthe microscopic world
or the world
or other circumstances where things are
very different from whatwe observe in day to day
like temperature or something like that.
And then classical physicsexplains our everyday world.
So in principle,
quantum theory should merge
(20:54):
as we scale up the size of the object
or as we'll scale up the temperature
or something like that of the system.
Quantum theory should very smoothly merge
into classical physics.
And we should be able tounderstand that convergence
because classical physics is not wrong.
At least, we know that,
know that most of the thingsaround us is spread is,
could be predictedusing classical physics.
(21:16):
This is the field of quantumclassical correspondence
and it is more or less,
fairly understood forintegrable or regular systems,
but for chaotic systems,
it is not still understood.
- Why is that?
Is it just because it's aextremely difficult subject
that's difficult to measure,
you're dealing with tiny microscopic--
(21:36):
- So there are fundamental differences
how in the formulationof quantum mechanics
and classical physics, actually.
In classical physics,
we've see chaos throughtrajectories actually
in phase space,
like phase space is somethinglike you take the position
and momentum of a particle
and then track how theposition and momentum evolves
(21:56):
and it will curve out atrajectory in the phase space.
- And what's a trajectory?
Just kind of the path that it follows.
- Yeah, that's right.
But not just position,
you have to add, there isanother axis, which is momentum.
So in general, when we see a particle,
it's just position, right.
But there is a momentumassociated to the particle,
which is for normal particles.
It is mass times velocity.
(22:19):
So that is another axis.
So the phase base is formulatedby position plus momentum.
So classically it is possible to measure
the position and momentumof particles precisely.
And the chaos occurs inthe finest structures
of the phase base
carved through thesetrajectories actually.
But quantum mechanically,
due to Heisenberg's uncertainty principle,
(22:41):
we can't have precise values of
position and momentum at the same time.
So we don't have trajectoriesin quantum mechanics
just like the way we haveit in classical physics.
So this is one of the fundamental reasons
we can't pick up the definition of
chaos in classical physics
and use it in quantum physics actually.
(23:04):
So just because quantum physics
is formulated in a very different manner
than in classical physics,
understanding chaos in quantum physics,
the same way as it isdone in classical physics
is not possible.
But as I talked about earlier,
there should be a smooth convergence
of quantum physics into classical physics
as we scale up the,
the size of the objector things like that.
(23:25):
And in quantum mechanics,
the superposition and entanglement
are two purely quantum properties,
not there in the classical world.
And entanglement is like,
if you have a,
we were talking about quantum coins.
So if you have a couple of quantum coins,
if the coin is classical, you both,
if both can be in headsor both can be in tails,
(23:46):
or one can be head and one can be tail.
But quantum mechanically,
you can have a statelike a superposition of
head, head, plus tail tail,
something like that.
And when you measure one of the coin,
if the pair of quantum coin
is in this state that I talked about,
head head plus tail tail,
(24:07):
then if you measure one coin
and if it comes out to be heads,
the other coin is bound to give heads
when you measure it.
Likewise, if the firstcoin comes out to be tail,
when you measure it, the othercoin is bound to be in tail.
- And this is even if the two coins
are far away from each other.
- Yeah, this.- Held by,
(24:27):
handled by separate people.
Is this, this is what Einsteinsaid was spooky action.
- Yeah, that's right.
- Where it's where it seemslike one thing far away
is happening at the very same time is as,
as a different thing.
I know that's
probably not the scientific explanation,
but that's, is it fair to say that
that's one of the thingsthat we just don't experience
(24:48):
in our everyday lives?
- Yeah, that's right.- So we have a hard time
wrapping our heads around it?
- Yeah, that's right.
So that's the thing
that if you preparethese two quantum coins
and suppose you give one of them to Alice,
other of them to Bob,
and if they are prepared
in this joint quantum state,
entangled quantum stateand Alice suppose goes,
goes to Australia andBob lives here in Canada,
(25:08):
and then Bob measures his quantum coin.
And if he gets heads
and then instantly Alice will observe
if she makes a measurementon it, on her coin,
that it is in head actually.
Likewise, if Bob gets tails,
then Alice will see to be tail.
So that's the thing like.
(25:28):
- That is spooky.
- That is spooky.
And that's the thing that we have observe.
This is called non-local correlation
because it's not likea measurement in Canada
is affecting something inAustralia and instantly.
So, and we know that information
can at most travel withthe speed of light.
(25:50):
It can't travel beyond that.
So how does this happen?
So that's why it is callednon-local correlation.
The thing is like,
this is very surprising that this happens,
but it is found to be true inseveral experiments, actually.
So, and it is still a question
like, how does this happen?
How do we understandactually, that this happens.
(26:12):
It is very, very surprising in that way.
- It seems like there are
a number of mysteriesthat need to be solved.
And you've mentioned sort of the big,
a big one of,
at what point does the quantum world
sort of move into theclassical world that we inhabit
and why is it so hard tosort of pin that down that,
(26:35):
that making general relativity
and quantum mechanicsplay nicely together?
Because that seems to bethe focus of a lot of work
is understanding the,
the change between quantum and classical.
- So these are two differentquestions actually.
- Okay, well then, yeah,I can rephrase that.
I guess I'm getting at this question of
understanding where quantum ends
(26:57):
and where classical begins and,
and why there's not sortof a total agreement there.
Why is it so challenging to find this,
I guess unified theory?
- Quantum classical correspondence,that's a correspondence
that's why is an active areaof research actually like,
and we don't have an answerto that, I guess why.
(27:21):
- Maybe my follow up question is then
it's for decades, people havebeen working on this challenge
and it's a big challenge.
Is it not daunting as a scientist
to take on challenges that are so
unsolved for so many years?
- So it is unsolved for so many years,
but it's not like noprogress have been made.
(27:42):
Like there have been so many
different kinds of properties that we see.
Like we can classify systems,
whether they're using classical mechanics,
whether they're integrable or not,
or chaotic or not,
depending on like, whether it,
whether the system has a classical analog.
So there are several quantum properties
(28:03):
that people have come up with
in these studies
where they see thatthey behave differently
when the classical analogis integrable or chaotic.
But all of these properties,
what we have found isthere is some exception
and physics is a study.
Physics is a, is a like,
(28:24):
field where
most of the innovations happen
when we see an exception, actually
like if we had thought ofwhat the photoelectric effect,
as an exception, study it separately,
that it doesn't follow therule of classical physics.
We wouldn't have this third theory
of quantum mechanics now, right?
So whenever you see an exception,
that is the area of growth.
(28:45):
So like, so many advances have happened,
but we still do not have a single answer.
And there is a possibilitythat after a few more years
or after a couple of decades or something,
there are so many pieces of this puzzles
that people have found.
There will be someone whocan glue all of them together
(29:06):
and find an answer.
- Might it be you?
- Hopefully.
- Is that a hope that,
a sort of professionalgoal that over your career,
you will move this fieldforward a certain amount?
- I mean, I started my researchwith that goal actually,
and I have made small progress
(29:27):
in some of the questionsor the conflicting answers.
And I hope that that isthe big goal, actually,
that I hope someday
if I can answer how quantumclassical correspondence happens
in chaotic systems.
Like that is a big goal.- Yeah.
- I hope someday.
If possible, me, that's fine.
Like otherwise someoneanswers that question.
(29:50):
- And so why did you choose
to come here to the Perimeter Institute
to kind of help make progress
towards entering that question?
- Perimeter Institute is a place
where like there's so many,
it's a theoretical physics place
and being a theoreticalphysicist, like a perfect place.
And then other thing is like,
there are so many differentareas of research here and
(30:13):
people like so freely collaborate with
other people in other areas.
And these intersections aremost interesting actually.
Like I started my PhD,
I wanted to work in quantum chaos,
but then my advisor
had worked
in quantum information.
So she gave me like this
(30:36):
problem of
understanding quantum chaos
through this quantum informationperspective, actually.
And then I got into thefield of quantum information
and then here, like wehave different fields.
Like I have collaborations withother postdocs and quantum,
quantum foundations and condensed matter.
(30:57):
So those intersectionsare really interesting
finding people from other areas.
And it's a very activeplace in the sense that
there are so many visitors
from all around the world, actually like
giving talks on so many different topics.
So using techniques
and tools from one
branch to other branch,
(31:18):
that's where I think
sometimes major innovations happen.
For example, like quantum,
quantum information is onething that has led to like
the tools and techniquesin quantum information
has been used from condensed matter
to high energy physics, actually,
like black holes also,
you have this black holeinformation paradox or something.
(31:39):
And in condensed matter,
you have these questionsabout thermalization,
(mumbles), and where tools and techniques
from quantum information have been used
to answer some of the questions.
So these intersectionsare really interesting
and that happen a lot at parameters.
So I'm really excited to be here
and collaborate with other people.
- Yeah.- That's fantastic.
I was just,
(32:00):
I wanted to ask
a little bit further back in your past.
Were you always,
since you were a little kid,
interested in quantum physics?
How did you find this career path?
- It started in my highschool that I became,
became fascinated with physics.
I think in my primary school,
I was more interested in maths.
(32:22):
I think I had an analyticalmind and always took a,
a delight in like solving problems,
difficult problems actually, like.
- I read that you would solve problems,
logic problems from a magazine.
- Yeah, that's right.
- Yeah, just on your own, just for fun?
- Yeah, it was mostly for fun.
I had elder siblings who were preparing
(32:43):
for general competitive exams
in which there were maths andlogical questions actually.
And it was a fun to seewhether I could solve them
in my school.
So that happened.
And then in my high school,
preparing for a national levelengineering entrance exam.
And in that, in that exam,
basically problems that werethere were very complex.
(33:06):
Like it was not just formula based
that you are given a problem
and you have these variables
and this is the formula,
you plug in the variablevalues and you get the answer.
That is not the kindof questions, like it.
You had to think from firstprinciples actually to,
to solve those complex problem.
So I was preparing for that exam
and I had joined a coaching class,
(33:29):
which was very usual back in India.
- Coaching for this particularexam, like tutoring,
to learn how to take the exam?
- High school students,
one thing is you have to giveschool exams like board exams.
And then another thing is youhave to get into a college
or university after that.
So these national and level entrance exam,
these coaching classes,
(33:49):
they taught things
at a more fundamental level.
Like board exams was slightlysimpler in the sense that
as I said, you can have variables
and plug in a formula lineand you will get answer,
but to crack these entrance exams,
you really needed to thinkfor, from first principal.
So the teacher,
like my physics teacher in my high school,
(34:09):
in my coaching class
played a very, very big role, I would say,
where I became fascinated with physics
because he taught us how to think
from first principles,like given a problem,
which seemed very complexin the first place.
And I would be like, there'sno way I can solve it.
And then when you startwith these first principles,
just like the very basic equation,
(34:30):
which is, I think it was to Newton,
Newton's second law.
If you understood this equation well,
there was so many types ofproblems that you can solve,
very complex problems.
And just seeing that,
that everything combinestogether in this simple equation
and you can solve difficult problems,
(34:51):
seemingly unsolvable in the first place,
that gave me another levelof delight, I suppose.
And I enjoyed this
and the way my teacher taught,
I really imagined myself like,
I felt like I wish I coulddevelop some of these equations
or something like that.
That was so fundamental using,
which you can explain so much,
(35:12):
so many phenomena in the world.
So that really made methink that I wish, I mean,
pursue this researchcareer in the first place.
- And where did you go from there?
You went to undergraduate studies.
- Yeah, so I cracked thatengineering exam, national level.
- Yes, you told us, I believe,
(35:33):
of the 400,000 people that took that exam,
you're in the top, what, one, 2%.
- Two top 2%.
- So you weren't gonnamention that on your own,
'cause you were being too humble, but she,
she aced the exam, then what happened?
- Yeah, so I was able to crack that exam
and then I went to anengineering institute
(35:54):
and I was there for a year,
but somehow I didn't feelquite at place there.
Like,
and I didn't,
couldn't picture myselfbecoming a researcher
after studying there.
I don't know why.
I just didn't feel like it.
I still tried to understandwhy that happened.
And at the age of like 18or something like that,
(36:16):
deciding to put a place likethat and go to a new college
was a risky decision,
not supported by many,
but I was not feelingat home at that place.
And then I wrote an examfor another institute,
undergrad institute, whichwas more research focused.
I qualified that exam.
(36:37):
So I went ahead joiningthe other institute
where I did a bachelor'sdegree in physics.
- And I really wanna asksomething here because
for those who mightnot know, I know Meenu,
you wrote such a really nice article
as part of this story,
"What is it like to bea woman in physics,"
which is a collection of stories
by women here at Perimeter Institute.
(36:57):
And I just wrote down oneof my favorite quotes.
You said,
it was not normal for a small town girl
from a conservative society like me
to leave home for undergraduate studies,
let alone later travelto a foreign country
for graduate studies.
And the rest of yourstory is really great too.
And I just was wondering
if you can kind of speakto that piece a little bit.
What was it like to make that decision
(37:19):
to challenge those societal norms?
- I was very scared inmy school time actually.
Like I was seeing most of the women
around struggling actually.
Like I have a bunch of likevery strong-headed women around
in my back in my family,or extended family,
but I still see that tryingto break any social norm.
(37:42):
Like they have to put so much effort.
And after putting in so mucheffort, little by little,
it breaks them down somewhere actually.
And that hard life that I was seeing,
all of them living,
I felt like I really needto have a better life,
which I can live on my own terms.
(38:04):
It was not normal for familiesback in those days actually
to send their girl,
girl child to study outsideof the hometown, actually.
It was not considered safe or something.
It's norm, it's relatively normal now.
But at, in those timesit was not that normal.
If I could crack thisprestigious exam called ITJ,
(38:26):
it was very prestigious
and it would be a prestige for the family.
They will be willing to sendme if I can crack this exam.
So I put in a lot of hard work and effort
and I was very, very scared.
What if I couldn't crack it?
Like I will be stuck here.
But with hard work, I think hard,
hard work and conviction,
(38:47):
I was able to crack thatexam and leave home.
So it was slightly difficult.
- And home, home is a relatively,
I think it's Gaia and India, Gaia.
- Yeah.- It's,
it's more of a tourist place.
I think it's a spiritual destination
because there's connections to Buddhism.
- Yes, that's right.- It's probably not a place
(39:07):
where a young girl saysI wanna be a physicist
and gets the warmest reception.
What kept you going whenthere, you said you,
you met opposition atstages along your way?
- First of all,
I really liked studying
and solving analyticalproblems in physics and math.
That was one thing.
And the other thing was like
that conviction that I want a better life.
(39:30):
So both of those things like,
and the third thing,
like I really got amazing teachers
like these coachingclasses I am telling about,
like I had three different teachers
who were extremelysupportive, always there.
Taking classes from themreally, really helped.
And they were there to answer my questions
(39:51):
or support me in any way they can.
So their presence meanta lot at that time,
actually their belief in me
that I can do something,I can crack this exam,
even though it is difficult,
that really helped.
Due to those factors,I was able to make it.
- And moving, you know,
from a small hometown to another city,
(40:12):
let alone a country on theother side of the world,
that was a big,
was that moving to Canada to do grad,
to do a PhD,
was that a,
a difficult leap for you to make
or was that always in the cards
that you would go somewhere to,
somewhere else to become a researcher?
- I don't exactly rememberwhen was the first time
(40:33):
I really thought that I couldgo to a different country
and live by myself and study on my own.
That was,
that was not something thatI thought from the beginning,
but then in my college,
like I was the third batch,
there were two more senior batches than me
and I was seeing other students,
including women, going out
(40:54):
to other countries for research projects,
summer internships orfor graduate studies.
And I just felt like ifthey could do it, I'll,
I'll be also able to do it.
So I followed their footsteps in that way.
So, yeah.
- And you created your own footsteps too,
you know, for others to follow.
- Yeah, hopefully
it will inspire others as well.
(41:15):
- It's interesting, right.
I think for so many people
it's so important to havethose role models, right?
Whether they be your colleaguesthat are a year ahead of you
or somebody that's maybealready a professional
in the field.
Was it important to you to have
role models at maybe differentlevels along the way?
- Yeah.
So my first role model Iwould say is Kalpana Chawla.
(41:36):
Unfortunately she is no more.
So Kalpana Chawla,
she was the first Indianwoman to go to moon,
actually during her second trip to moon,
there was a crash
in that shuttle and unfortunatelythey all passed away.
So yeah, she was a big role model for me.
(41:58):
Like she came from a small town
in another state in India,
which is Punjab,
and seeing her like reading her story,
knowing about her.
I felt like if I followed her footsteps,
I could do something as big as her.
(42:18):
So that was really important.
Looking back, I,
I can never think that Icould have looked up to Neil,
Neil Armstrong for example,
and thought that I couldhave done something similar
or something like that.
But having someone who has same gender,
same ethnicity, sameback family background,
like similar kind of family background.
(42:38):
And you can dream big
if you see some other people
with similar situation
dreaming big and being able to make it.
So in my childhood,
I always dreamed offbecoming an astronaut,
just like Kalpana Chawla,
changed over time.
But I think her presence
and whatever she achieved in her life,
(42:59):
knowing that helped me dreambig, at least in my life.
- Yeah, that's amazing.
- Amazing.
- Would you,
if someone offered youa chance to go to space,
now that space tourism is a thing,
would you wanna be an astronaut still?
- I think I'm less of a tourist
and more of a person from research.
Like if it was more of anopportunity to go there
(43:21):
from a research point of view,
I think I would be more interested
rather than just goingthere and seeing things,
how it looks like.
- If you did have to nowsay what's your dream,
what would it be?
Would it be to crack thisquantum classical correspondence?
- If I could play
good enough role intracking that question,
that would be really nice.
(43:42):
But apart from that,
like all these innovationshappening in quantum computing,
I keep on thinking to the day, like, it,
sometimes it seems like it is a big dream,
which may or may not happen.
But then I keep on thinking that
about the time when classicalcomputers were devised,
like the first computer
were like the size of a big room.
(44:02):
And now it's like in our hand.- Yeah.
And actually at the Institutefor Quantum Computing
where you were,
some of the quantum computers,
there are the size of a room.
It's, it's a,
it's a similar analogy there.- Yeah.
- Quantum computing is sortof at that infancy stage,
but you can see the,
the potential and yougot to work right in the,
in the middle of a quantumcomputing research center.
(44:24):
- Yes, that's right.- Well, I,
I love the way you put it earlier, too,
that sometimes doing research
involves putting together
so many little pieces of a puzzle, right.
And you have these pieces.
It's not always obvioushow they fit together
and it's not always obvioushow many pieces there are,
how long it's gonna taketo put them together.
But I think even figuringout how to glue together
two pieces is,
(44:46):
is a big accomplishmentin many cases, right.
- Yeah.
- I'm curious to know ifyou still have that same joy
that you felt when youwere a kid solving puzzles.
If doing math and solvingdifficult problems,
is it still fun?
Is it still like a hobby foryou the way it was as a child?
- Yeah, like whenever I get any new idea,
I'm very excited to try it out,
(45:07):
whether it'll work or not.
That's the most excitingpart of my research projects.
Like, and these ideasjust happen to come around
like while I'm doing some stuff,
which doesn't require a lotof attention, for example,
washing dishes or cookingor something like that, or,
or waiting at the bus stop for the bus.
So these are the moments when
(45:28):
some ideas will just come to my mind
and then I'm so excited to try it out,
whether that will work or not.
And that is the most joyous part of
being a researcher for me.
- Interesting, even ifit doesn't work out,
even if the idea fallsflat and doesn't pan out?
- So as long as a few ideasare working out out of many,
(45:50):
like as long as two or twoideas are working out out of 10,
suppose, that's fine.
It will be a little frustrating if
I thought of 10 ideasand nothing worked out.
(laughs)
But luckily,
if I think of 10 ideas,
two to three ideas turn out to work so.
- Trial and error only workswhen there's some error.
(46:11):
So yeah, you need to.- Yeah.
- Well, Meenu, we nowwanna take some questions
if that's okay.
So we, you know, as part of this,
we wanna see what otherpeople wanna ask you as well.
And so we have a question today
that was actually sent in by a student
from our PSI program hereat Perimeter Institute.
So for those that might not know,
PSI is a one year master'sprogram in theoretical physics
(46:32):
here at Perimeter Institute.
I actually teach in that program.
I teach lectures in quantumscience and machine learning.
So we have a question here
that's from one of ourstudents named Anna Kinur.
- What does it mean to do research
through the lens of quantum information?
Do you really think the world
can be reduced to only information?
(46:54):
- First of all, thanks alot, Anna, for that question.
That's a great question.
So the thing is in my research,
since I started my PhD,
I started working on quantum chaos
through the lens of quantum information.
So that has been a majorityof my part in my research.
So I can't really speak of a general term,
(47:15):
in general terms, what it means to
research and from other perspectives,
a lot.
The thing is quantum information,
I see it as something that has
brought together differentfields in physics,
like it has provided a newperspective in different fields.
For example, in condensedmatter to high energy physics,
(47:36):
which look like distinct topics, actually
in the first place.
Like if you go back like 30, 40 years ago,
all those physicists,
you can classify them ascondensed matter physicist
or high energy physicist.
But now that's not the case.
For example, I would talk about
a faculty here at Perimeter, Beni.
Like he works at so much, like he is,
(47:56):
he is very much into high.
- Beni Yoshida?- Yeah.
- We know Beni.- Jinx.
- Yeah, so he works very muchinto high energy physics,
like black holes stuff,
as well as condensed matter physics.
And he is a faculty
in the quantum information research group,
looking at things from thepoint of information perspective
gives us more pieces of the puzzle,
(48:18):
the bigger puzzle of physics actually.
And it definitely helps.
And maybe it'll be
piece that solves biggerproblems in physics, who knows.
- So it's not necessarily about
answering every possible question,
but giving a new way to lookat or a new perspective.
Yeah, oh, cool.
- To the existing problems,
other fields of physics actually.
(48:39):
So it's definitely an interesting way.
I have been working init for seven years now
since the start of my PhD
and I have really enjoyed it.
- I have a question fromsomeone named Ahmed,
a student here in Waterloo region,
and he asks why can't quantum mechanics
agree with relativity?
- Thanks, Ahmed for that question.
So thing is generallya theory of relativity,
(49:02):
space time is continuum.
Energy is also continuous,
but in quantum mechanics,
space time is at equal footing
in general related theory of relativity
and energy is a continuous thing.
But in quantum mechanics,
at least in the starting,
if we talk about the starting or picture,
space and time are at different footing,
plus energy is discreet.
(49:23):
It is quantized.
And other thing is like,
we still do not have aquantized period of gravity.
Like those pieces are required
such that we can glue together
general relativity and quantum physics.
- Is that quantum gravity that's--
- That's the bigger umbrella, yeah.
In which people are trying to figure out
(49:44):
how to quantize gravity
so that we will be able toglue together these two fields.
- So there's a whole field of research
devoted to answering thatquestion, I guess, yeah.
- Many faculties here, Iguess working in that area.
- Well Meenu, you've beenso generous with your time
and it's been reallyfascinating chatting with you.
Thank you for joining us.
It's been great.
- Yeah, thank you.
(50:04):
This has been just so much fun.
I've really enjoyedlearning more about you,
even though I've known you for years,
I've learned so much about you.
So thank you so much forsharing your time with us.
- Thanks a lot, Laurenand Colin, for having me.
(upbeat music)
- Thanks for steppinginside the Perimeter.
If you like, what you hear,
(50:25):
please help us spread the word.
You can rate,
review and subscribe
to "Conversations at the Perimeter"
wherever you get your podcast.
Every review really helps us a lot
and it helps more scienceenthusiasts find us.
Thank you for being part of the equation.
(upbeat music)
(soft music)
(00:09):
- Hi everyone.
And welcome back toConversations at the Perimeter.
I'm Lauren.
- And I'm Colin.
- And today we're bringing you
a conversation with Meenu Kumari,
a postdoctoral researcherhere at Perimeter Institute
who specializes in quantum chaos.
- Quantum chaos.
You know, that's a term
that I actually haven't encountered before
our conversation with Meenu,
(00:30):
despite talking to a lotof theoretical physicists,
that, that idea of quantumchaos was, was new to me.
And I was fascinated tohear about it because
when I first heard it, honestly,
it sounds a bit like somethingoutta science fiction.
- Well, Meenu has actuallybeen a friend of mine
for many years now,
but I still learned a lotfrom this conversation
about her life, her journeyto where she is today
(00:50):
and her research in the quantumto classical correspondence
and really studying how we can move
between these quantumand classical realms.
So without further ado,
let's dive right into the quantum chaos.
- Meenu Kumari.
Thank you so much for joiningus here at Perimeter Institute
(01:10):
in our, in our beautifulbut empty theater.
Thanks for joining us.
- Thanks a lot for having me.
- So Meenu, thank you so much
for sitting down with us today.
I'm really excited to talk to you.
Maybe you can just start bytelling us what you do here
at Perimeter, what your role is,
and also what you'reinterested in studying.
- I'm a postdoc in the quantuminformation research group
(01:31):
at Perimeter.
I joined in September, 2019,
and I did my PhD at IQC atthe University of Waterloo
from September, 2014 to August, 2019.
- So IQC, that's the Institutefor quantum computing,
just down the road from here.
So is quantum computingpart of, of what you do?
(01:54):
You're a theorist.- Yeah.
- And quantum computingsounds like it's for machines.
So can you explain
how you're connected to quantum computing?
- My field,
my research is in the fieldof quantum information,
using the tools and techniquesof quantum information
to study other questions in physics.
The thing is
(02:15):
quantum computing uses
quantum information techniques
or for quantum processing techniques
to build like quantum computer,
like so many tools
and techniques have been developed
in the field of quantum information,
which can be used
in other fields of physics,
like high energy physics,
or (mumbles) metaphysics
(02:37):
to study other questions.
So quantum information is basically
like
world is fundamentally quantum, right?
If you--- Oh, so,
just to interrupt the worldis fundamentally quantum
in the sense that
at the underneath everything,
quantum mechanics sort of describes how,
how the world works at this small level.
If you dig deep enough into anything
(02:57):
you'll get into the quantum realm.
Is that fair?
- Yeah.
So the thing is like
first classical physics was developed,
which is like Newtonian mechanics,
Galilean relativity
and then Hamiltonian mechanics and so on.
So those theories describe the world
at the macroscopic level
(03:18):
very well, actually.
But towards the end of 18th century,
like around 1890 or something,
there were so many phenomena that,
that we are discoveredexperimentally, which,
which were not,
which the physicistswere not able to explain
using the Mecca,
using the formulationof classical physics.
So they started to diginto what's going on,
(03:39):
trying to understand, for example,
for the photo electric effect.
Around 1920 to 1930,
this new formalism of quantummechanics was developed.
And over the years,
we have seen that
whatever we can predict
from the theory of quantum mechanics,
most of the experiments that we do today,
the results of those experiments can be
(04:01):
explained using the theoryof quantum mechanics.
So that's the thing that theworld is fundamentally quantum
because almost all the experiments
at the microscopic level,
or at atomic level basically,
can be explained using the,
using the theory of quantum mechanics.
Although the formulationof quantum mechanics is,
is quite non-intuitive.
- So I have a question there.- Yeah.
(04:22):
- So as you started to allude to,
there's so many researchfields that people work in now
that are studying differentquantum properties of matter.
So you mentioned quantuminformation, quantum computing,
there's also quantummatter, quantum foundations,
quantum field theory.
There's probably a lot of other fields
that have the word quantum in them.
So can you just tell us a little bit
(04:44):
about that word "quantum"
and really what are someof those quantum features
that are so interesting
and confusing as opposed to
the features we might be moreused to in classical matter?
- Yeah.
So two of the most intriguing features
are the principle of superposition
and the principle ofentanglement actually,
Schrodinger's cat is a famous example.
(05:06):
Unless until you look at it,
you don't know whetherthe cat is dead or alive.
So.
- I'm, this is,
this is the famous thoughtexperiment with the cat in a box.
And it's a,
it's a sort of metaphor for things
that can be in one stateor another at the same time
until they're measured.
So you don't know if this cat.
- Yeah.
- I, when I was younger,
I thought that was a real cat
(05:26):
in a real box and a real experiment.
I'm glad to know it's not.
(laughs)
So that explains superposition,
this idea of things in the quantum world
being in a state that'smore than one thing.
- Yes.- At the same time.
- Yeah, that's right.
So for example, if youtake a quantum coin,
a classical coin is eitherin the state of heads,
(05:47):
like if you flip it, itis either heads or tails,
but quantum coin can bein a superposed state of
heads and tails,
and then you measure it
and you will get either heads or tails
out of your measurement result.
By measuring it again and again,
you will find probabilities
of getting heads as well as tail
(06:08):
and using that, you canconstruct the quantum state.
So the quantum coin is basicallyin a superposition state.
It is not just only in heads
or in tails.
Like quantum mechanicsisn't a simple theory.
It's not,
it doesn't describe one single instance
of a particle or something.
(06:29):
Like it describes,
like if you do something
over and over many times,
what will be the output that you'll get,
like what will be theprobability of getting.
- It works more in likelihood
and probability than an exact prediction.
- Yeah, that's right.
So if you just measure it once
and see whether it is tail, heads,
you can't really say that it,
(06:50):
whether it is in thesuperposition state of heads
plus tail, or whether it is really heads,
you will have to perform
the measurement on the same copy,
on the multiple copiesof the same quantum state
again and again to figure out whether
it is in a superposition state or not.
- This is part of whatconfuses a lot of people
about quantum mechanics, right?
(07:11):
This is 'cause we don't experience that.
When we flip a coin, it'salways heads or tails.
- Yeah, that's right.
- Cause it's a, it's a macro world coin.
So it's okay that peopleare confused by this, right?
It's not something we experience.
- Yeah.
It is very non-intuitive,
like we don't really observe anything
in a superposition state.
So that's where quantumfoundations come in.
(07:33):
We describe
a quantum particle
using a wave function,
which can be in a superposition state,
but we don't reallyobserve that wave function.
What we observe is
probabilities of certainkinds of observables,
like any real observable,for example, for,
with this coin,
when you measure it in the basis of head,
(07:54):
head and tail, when you measure it,
whether you'll get heador a tail, actually.
So quantum foundation is like
trying to understand what is real
versus what we infer out of measurement.
So this whole (mumbles)mathematical formalism
of wave function
is a mathematical construct
(08:15):
because we can't see the wavefunction (mumbles), right.
That the quantum particleis indeed in that state.
We can only infer observables,
measurements of observables actually.
- Right.
- So quantum foundations deals with
trying to understand what is real
versus what we can observe.
(08:36):
Like what is the connectionbetween those two.
- And I just wanna goback to something you,
a word that you said a few sentences back,
you were talking about
trying to measure these quantum states.
And you've talked about doing that
on many copies of the same state,
but I think that word copy
is maybe something we should talk about
because I think there'sanother interesting property
(08:57):
in quantum mechanics,
but you can't actually
make an exact copy of a state.
Is that right?
- You can,
you can't make an exact copyof an unknown quantum state.
So that's no cloning theorem actually.
Like once you know what is thequantum state mathematically,
you can prepare many copies of it.
But if you don't know
(09:17):
what is the quantum state of a particle,
you can't copy it.
And that is a principle that is,
that would be used in manydifferent types of applications
of quantum information
and quantum computing,
actually like quantum cryptography.
- And that's different thanin classical cryptography.
Is that right?
- Yeah.
Like you can create copiesof something basically
(09:37):
in quantum, classical cryptography
without other peopleknowing about it actually.
But quantum state,
like as soon as you measure,
the quantum state of particleis destroyed actually.
So once it is destroyed, the other,
the receiver end will know
that
it has been intercepted by,
(09:59):
by some Eve actually.
- Is that the quantum cryptography
or the idea of quantum encryption
that measuring a quantum state changes it
and therefore you can detectwhether it's been measured?
- Yeah, that's right.
- So, and that's a,
that's sort of a branchof quantum computing
and quantum information.
I wanted to get back to that
'cause you said you workat these intersections
(10:21):
of quantum information,
which is related to quantum computers,
which are in theory,
these very powerful computersthat harness superposition.
And, but you said you'reat the intersections
of quantum computingand quantum foundations.
So which questions are currently sort of
the focus of your attention?
What are you trying to figure out?
- I became interested in,
(10:44):
in chaos actually.
So initially I did a few projects in my,
during my undergrad studies
in the field of classical chaos.
And then I did a project
in the field of quantum chaos.
- So can you actually just start
by telling us what classicalchaos is maybe before we,
I know that's not really what you work in,
(11:05):
but it might be useful to start there.
- Chaos is a pretty loadedterm, non scientifically,
but chaos is a veryspecific meaning in your.
- Many people would be familiar
with the term butterfly effect.
So it is like if,
can the flap of a,
of the wings of a butterfly
in Brazil cause a tornado say in Germany.
(11:27):
So that's the butterfly effect,
can very small changesin the initial conditions
lead to vast differences in the outcome.
Chaos is basically unpredictability due to
sensitivity to initial conditions.
Like the seeds of chaos theory
were sewn by Henri Poincare,
but then it was well formulated
(11:47):
by a meteorologist, EdwardLorentz, around 1960s,
had built a weather model and.
- Sorry, a meteorologistcame up with chaos theory?
- Yeah.- Okay.
I didn't know.
Is weather and meteorology is that,
that's classical chaos theory,
that has nothing to do with quantum.
- Chaos is basically a property
of classical dynamicalsystems, not just physics,
(12:11):
like any kind of dynamicalsystems you want to predict.
Like for example,
the population of fish in a pond
or weather is another example.
And then even in stock marketor something like that,
chaos has applications in every,
so many fields actually.
So dynamical system is basically
any system that evolves with time.
- Sorry, you said a,
(12:31):
a dynamical system.- Dynamical system.
It's any system that evolves with time.
And so you basically haveeither differential equations,
like you have a set ofvariables, for example,
for whether you can havevariables as temperature,
pressure or something like that.
And differential equations
telling us how thoseevolve with time basically.
(12:53):
So now these differential equations,
if they are nonlinear,
if they nonlinearly dependon the other variables,
then it results in.
- Maybe I'll, I'll just ask a question
to make sure I'm understanding.
You're saying that, you know,weather can be an example.
So is this why I mightsometimes look at my phone
and see that it'ssupposed to rain tomorrow,
(13:14):
but then it doesn't actually rain.
Is that, is that because
it's very difficult to predict,
is that related to the factthat it's a chaotic system?
- The weather is a chaotic system.
That's right.
So the thing is like,
we all know that we can'treally predict the weather
of any place.
Like for example,
if we look at the weatherof Waterloo today,
how is it going to betomorrow or day after?
(13:36):
And we see that many times,
it's not the same as whatit is tomorrow, right?
So why is that the case?
We have advanced technologically so much,
but still we can't reallypredict the weather
a few days in advance of any place.
If we had predicted,
like if we could havepredicted so many catastrophes
(13:59):
and on earth would have been,
could have been like avoided,
or not avoided,
the destruction could have been avoided.
- Yeah, if you knew a hurricane was coming
a month in advance,rather than a few days.
- Yeah.- In advance,
you'd be.- Something like that.
- You'd be grateful for chaos theory.
(laughs)
- But the thing is
they are predicted onlya few days in advance
with some probabilitythat this could happen.
(14:20):
So it is because likethese models are nonlinear,
so they can't be solved exactly.
And they can exhibit chaos that
whatever initial condition we input,
for example, the temperature or pressure,
whatever we input in,
in the bunch of,
for the variables in the bunchof differential equations,
those variables will havesome error in the last visit.
(14:44):
Like if we have five visit (mumbles)
in our value of the temperature,
there is a small error in the fifth visit
after the decimal, right?
So that very small error
in the last visit
actually can amplify
upon evolution of the system.
- Right.
- The more precise weare in the initial value.
(15:07):
- String of digits after the decimal.
- Yeah.- Is.
- The longer we canactually predict the weather
to the likelihood ofthe weather in advance,
but it will lead tounpredictability after some time,
no matter how much precision you're given,
there is going to be some error in the end
and that will lead tounpredictability in the long term.
(15:31):
So that's why weather isan unpredictable system.
But that's the thing.
Weather is a very complex model
and it may look like chaos is a property
of very complex models,
but that's not true.
Even very, very simple systems,
for example, double pendulum, is chaotic.
So double pendulum is basically like
you have some simple pendulum
in which you have a bob
(15:51):
attached to like some knob,
which oscillates in a plane.
Now you attach one more bobto the end of the first bob.
- So I have kind of a,
a stick or somethingwith a ball on the end.
And then I have another.- Yeah.
- Rod attached to that withanother ball on the end.
- Yeah.- And it can swing
(16:12):
independently of the first, right?
The first ball can swing,
would not independently but affected by.
- They will be dependent in some way,
but overall the motion is chaotic actually
like you can search variousYouTube videos actually that.
- They're really fun to watchby the way, double pendulums.
- Yeah.
- Good hypnotic entertainment.
(16:32):
- Very small initial condition change
can lead to highunpredictability actually.
So that's the thing,
that chaos is not just aproperty of complex systems,
but very, very simplesystems can exhibit chaos.
- Interesting.- So I,
I wanna ask something herejust to make sure I understand.
So you're saying with weather,
if I'm say measuring the temperature,
(16:53):
it might be, say 20 degrees Celsius,
but I'm not sure if it's 20 degrees
or 20.0001 degree Celsius.
This seems like a very small change.
And if it was a non chaotic system,
maybe the result two days later
wouldn't depend so much onwhether it was 20 degrees Celsius
or 20.0001.
But because it's such a complicated system
(17:15):
that's non-linear
and we call it chaotic,
it's in the end gonna depend a lot
on that really smalldifference in that variable.
Is that correct?
- Yeah, that's right.
So that small differencein nonlinear systems
put in principle amplifyto very large differences
in an unpredictable manner.
(17:35):
But if it is a linear system
or if it is an integrableor regular system,
like different words for the same time,
then those small differenceswon't amplify a lot actually,
or it'll amplify a verypredictable manner.
- I see.- If it'll amplify,
like there can be unstableboundary systems in ways,
things can amplify, but westill know how it amplifies.
(17:59):
So.- So,
may I jump in?
A quantum system,
is that more complex orless complex than weather?
Quantum being very small and,
and there's parameters around it.
What does quantum chaos refer to?
- Quantum chaos has not beenvery well understood yet.
Although it's been like a hundred years
(18:20):
of the development of quantum theory
and why is quantum chaos
and quantum classical correspondence
is an important problem.
I'll like to give another example.
For example, Galileanrelativity was well known from
a few centuries, right?
And then came in a specialtheory of relativity
where the speed of the objectcan be very, very high.
(18:44):
Now, as you start reducingthe speed of the object
towards normal speed,
special theory of relativity,
very smoothly merges intoGalilean theory of relativity.
It's not like Galilean theoryof relativity is wrong, right?
It is still right at the level
we observe our everyday world.
Then this new theory of,
(19:04):
this new theory of relativity was formed.
- By Einstein is?
- Yeah.- Okay.
- That's right.- I got that one right.
(laughs)
- And then it smoothlymerged with the old theory
where the old theory waspredicting things very well
in normal circumstances,
which we can observe through our eyes.
Likewise, classical physics is very,
(19:27):
can't very well predict our everyday world
that we see around
most of the things.
And then quantum theory
is something that describes phenomena.
The microscopic level
are at levels, which is,
does not happen in normal
or circumstance in forexample, very low temperatures,
chem temperatures near zeroKelvin or something like that.
(19:49):
We don't really see that.
So for example, super conductivity.
So you can see defectivesuper conductivity
at a macroscopic level.
It's a big object visibleto our eyes, right.
And we see that, but we can't ex--
- A levitating super magnetictrain or something like that.
- Yeah, that's right.
So,
so that happens at very,very small temperatures,
(20:11):
although it is macroscopic,
but quantum mechanics isthe thing that predicts it
where a thing is there,
there has to be somethingdifferent from normal circumstance
where classical physics fails,
for example, very,
very low temperature or very,
or microscopic scale
in terms of like size of anobject or something like that.
(20:33):
So quantum theory explainsthe microscopic world
or the world
or other circumstances where things are
very different from whatwe observe in day to day
like temperature or something like that.
And then classical physicsexplains our everyday world.
So in principle,
quantum theory should merge
(20:54):
as we scale up the size of the object
or as we'll scale up the temperature
or something like that of the system.
Quantum theory should very smoothly merge
into classical physics.
And we should be able tounderstand that convergence
because classical physics is not wrong.
At least, we know that,
know that most of the thingsaround us is spread is,
could be predictedusing classical physics.
(21:16):
This is the field of quantumclassical correspondence
and it is more or less,
fairly understood forintegrable or regular systems,
but for chaotic systems,
it is not still understood.
- Why is that?
Is it just because it's aextremely difficult subject
that's difficult to measure,
you're dealing with tiny microscopic--
(21:36):
- So there are fundamental differences
how in the formulationof quantum mechanics
and classical physics, actually.
In classical physics,
we've see chaos throughtrajectories actually
in phase space,
like phase space is somethinglike you take the position
and momentum of a particle
and then track how theposition and momentum evolves
(21:56):
and it will curve out atrajectory in the phase space.
- And what's a trajectory?
Just kind of the path that it follows.
- Yeah, that's right.
But not just position,
you have to add, there isanother axis, which is momentum.
So in general, when we see a particle,
it's just position, right.
But there is a momentumassociated to the particle,
which is for normal particles.
It is mass times velocity.
(22:19):
So that is another axis.
So the phase base is formulatedby position plus momentum.
So classically it is possible to measure
the position and momentumof particles precisely.
And the chaos occurs inthe finest structures
of the phase base
carved through thesetrajectories actually.
But quantum mechanically,
due to Heisenberg's uncertainty principle,
(22:41):
we can't have precise values of
position and momentum at the same time.
So we don't have trajectoriesin quantum mechanics
just like the way we haveit in classical physics.
So this is one of the fundamental reasons
we can't pick up the definition of
chaos in classical physics
and use it in quantum physics actually.
(23:04):
So just because quantum physics
is formulated in a very different manner
than in classical physics,
understanding chaos in quantum physics,
the same way as it isdone in classical physics
is not possible.
But as I talked about earlier,
there should be a smooth convergence
of quantum physics into classical physics
as we scale up the,
the size of the objector things like that.
(23:25):
And in quantum mechanics,
the superposition and entanglement
are two purely quantum properties,
not there in the classical world.
And entanglement is like,
if you have a,
we were talking about quantum coins.
So if you have a couple of quantum coins,
if the coin is classical, you both,
if both can be in headsor both can be in tails,
(23:46):
or one can be head and one can be tail.
But quantum mechanically,
you can have a statelike a superposition of
head, head, plus tail tail,
something like that.
And when you measure one of the coin,
if the pair of quantum coin
is in this state that I talked about,
head head plus tail tail,
(24:07):
then if you measure one coin
and if it comes out to be heads,
the other coin is bound to give heads
when you measure it.
Likewise, if the firstcoin comes out to be tail,
when you measure it, the othercoin is bound to be in tail.
- And this is even if the two coins
are far away from each other.
- Yeah, this.- Held by,
(24:27):
handled by separate people.
Is this, this is what Einsteinsaid was spooky action.
- Yeah, that's right.
- Where it's where it seemslike one thing far away
is happening at the very same time is as,
as a different thing.
I know that's
probably not the scientific explanation,
but that's, is it fair to say that
that's one of the thingsthat we just don't experience
(24:48):
in our everyday lives?
- Yeah, that's right.- So we have a hard time
wrapping our heads around it?
- Yeah, that's right.
So that's the thing
that if you preparethese two quantum coins
and suppose you give one of them to Alice,
other of them to Bob,
and if they are prepared
in this joint quantum state,
entangled quantum stateand Alice suppose goes,
goes to Australia andBob lives here in Canada,
(25:08):
and then Bob measures his quantum coin.
And if he gets heads
and then instantly Alice will observe
if she makes a measurementon it, on her coin,
that it is in head actually.
Likewise, if Bob gets tails,
then Alice will see to be tail.
So that's the thing like.
(25:28):
- That is spooky.
- That is spooky.
And that's the thing that we have observe.
This is called non-local correlation
because it's not likea measurement in Canada
is affecting something inAustralia and instantly.
So, and we know that information
can at most travel withthe speed of light.
(25:50):
It can't travel beyond that.
So how does this happen?
So that's why it is callednon-local correlation.
The thing is like,
this is very surprising that this happens,
but it is found to be true inseveral experiments, actually.
So, and it is still a question
like, how does this happen?
How do we understandactually, that this happens.
(26:12):
It is very, very surprising in that way.
- It seems like there are
a number of mysteriesthat need to be solved.
And you've mentioned sort of the big,
a big one of,
at what point does the quantum world
sort of move into theclassical world that we inhabit
and why is it so hard tosort of pin that down that,
(26:35):
that making general relativity
and quantum mechanicsplay nicely together?
Because that seems to bethe focus of a lot of work
is understanding the,
the change between quantum and classical.
- So these are two differentquestions actually.
- Okay, well then, yeah,I can rephrase that.
I guess I'm getting at this question of
understanding where quantum ends
(26:57):
and where classical begins and,
and why there's not sortof a total agreement there.
Why is it so challenging to find this,
I guess unified theory?
- Quantum classical correspondence,that's a correspondence
that's why is an active areaof research actually like,
and we don't have an answerto that, I guess why.
(27:21):
- Maybe my follow up question is then
it's for decades, people havebeen working on this challenge
and it's a big challenge.
Is it not daunting as a scientist
to take on challenges that are so
unsolved for so many years?
- So it is unsolved for so many years,
but it's not like noprogress have been made.
(27:42):
Like there have been so many
different kinds of properties that we see.
Like we can classify systems,
whether they're using classical mechanics,
whether they're integrable or not,
or chaotic or not,
depending on like, whether it,
whether the system has a classical analog.
So there are several quantum properties
(28:03):
that people have come up with
in these studies
where they see thatthey behave differently
when the classical analogis integrable or chaotic.
But all of these properties,
what we have found isthere is some exception
and physics is a study.
Physics is a, is a like,
(28:24):
field where
most of the innovations happen
when we see an exception, actually
like if we had thought ofwhat the photoelectric effect,
as an exception, study it separately,
that it doesn't follow therule of classical physics.
We wouldn't have this third theory
of quantum mechanics now, right?
So whenever you see an exception,
that is the area of growth.
(28:45):
So like, so many advances have happened,
but we still do not have a single answer.
And there is a possibilitythat after a few more years
or after a couple of decades or something,
there are so many pieces of this puzzles
that people have found.
There will be someone whocan glue all of them together
(29:06):
and find an answer.
- Might it be you?
- Hopefully.
- Is that a hope that,
a sort of professionalgoal that over your career,
you will move this fieldforward a certain amount?
- I mean, I started my researchwith that goal actually,
and I have made small progress
(29:27):
in some of the questionsor the conflicting answers.
And I hope that that isthe big goal, actually,
that I hope someday
if I can answer how quantumclassical correspondence happens
in chaotic systems.
Like that is a big goal.- Yeah.
- I hope someday.
If possible, me, that's fine.
Like otherwise someoneanswers that question.
(29:50):
- And so why did you choose
to come here to the Perimeter Institute
to kind of help make progress
towards entering that question?
- Perimeter Institute is a place
where like there's so many,
it's a theoretical physics place
and being a theoreticalphysicist, like a perfect place.
And then other thing is like,
there are so many differentareas of research here and
(30:13):
people like so freely collaborate with
other people in other areas.
And these intersections aremost interesting actually.
Like I started my PhD,
I wanted to work in quantum chaos,
but then my advisor
had worked
in quantum information.
So she gave me like this
(30:36):
problem of
understanding quantum chaos
through this quantum informationperspective, actually.
And then I got into thefield of quantum information
and then here, like wehave different fields.
Like I have collaborations withother postdocs and quantum,
quantum foundations and condensed matter.
(30:57):
So those intersectionsare really interesting
finding people from other areas.
And it's a very activeplace in the sense that
there are so many visitors
from all around the world, actually like
giving talks on so many different topics.
So using techniques
and tools from one
branch to other branch,
(31:18):
that's where I think
sometimes major innovations happen.
For example, like quantum,
quantum information is onething that has led to like
the tools and techniquesin quantum information
has been used from condensed matter
to high energy physics, actually,
like black holes also,
you have this black holeinformation paradox or something.
(31:39):
And in condensed matter,
you have these questionsabout thermalization,
(mumbles), and where tools and techniques
from quantum information have been used
to answer some of the questions.
So these intersectionsare really interesting
and that happen a lot at parameters.
So I'm really excited to be here
and collaborate with other people.
- Yeah.- That's fantastic.
I was just,
(32:00):
I wanted to ask
a little bit further back in your past.
Were you always,
since you were a little kid,
interested in quantum physics?
How did you find this career path?
- It started in my highschool that I became,
became fascinated with physics.
I think in my primary school,
I was more interested in maths.
(32:22):
I think I had an analyticalmind and always took a,
a delight in like solving problems,
difficult problems actually, like.
- I read that you would solve problems,
logic problems from a magazine.
- Yeah, that's right.
- Yeah, just on your own, just for fun?
- Yeah, it was mostly for fun.
I had elder siblings who were preparing
(32:43):
for general competitive exams
in which there were maths andlogical questions actually.
And it was a fun to seewhether I could solve them
in my school.
So that happened.
And then in my high school,
preparing for a national levelengineering entrance exam.
And in that, in that exam,
basically problems that werethere were very complex.
(33:06):
Like it was not just formula based
that you are given a problem
and you have these variables
and this is the formula,
you plug in the variablevalues and you get the answer.
That is not the kindof questions, like it.
You had to think from firstprinciples actually to,
to solve those complex problem.
So I was preparing for that exam
and I had joined a coaching class,
(33:29):
which was very usual back in India.
- Coaching for this particularexam, like tutoring,
to learn how to take the exam?
- High school students,
one thing is you have to giveschool exams like board exams.
And then another thing is youhave to get into a college
or university after that.
So these national and level entrance exam,
these coaching classes,
(33:49):
they taught things
at a more fundamental level.
Like board exams was slightlysimpler in the sense that
as I said, you can have variables
and plug in a formula lineand you will get answer,
but to crack these entrance exams,
you really needed to thinkfor, from first principal.
So the teacher,
like my physics teacher in my high school,
(34:09):
in my coaching class
played a very, very big role, I would say,
where I became fascinated with physics
because he taught us how to think
from first principles,like given a problem,
which seemed very complexin the first place.
And I would be like, there'sno way I can solve it.
And then when you startwith these first principles,
just like the very basic equation,
(34:30):
which is, I think it was to Newton,
Newton's second law.
If you understood this equation well,
there was so many types ofproblems that you can solve,
very complex problems.
And just seeing that,
that everything combinestogether in this simple equation
and you can solve difficult problems,
(34:51):
seemingly unsolvable in the first place,
that gave me another levelof delight, I suppose.
And I enjoyed this
and the way my teacher taught,
I really imagined myself like,
I felt like I wish I coulddevelop some of these equations
or something like that.
That was so fundamental using,
which you can explain so much,
(35:12):
so many phenomena in the world.
So that really made methink that I wish, I mean,
pursue this researchcareer in the first place.
- And where did you go from there?
You went to undergraduate studies.
- Yeah, so I cracked thatengineering exam, national level.
- Yes, you told us, I believe,
(35:33):
of the 400,000 people that took that exam,
you're in the top, what, one, 2%.
- Two top 2%.
- So you weren't gonnamention that on your own,
'cause you were being too humble, but she,
she aced the exam, then what happened?
- Yeah, so I was able to crack that exam
and then I went to anengineering institute
(35:54):
and I was there for a year,
but somehow I didn't feelquite at place there.
Like,
and I didn't,
couldn't picture myselfbecoming a researcher
after studying there.
I don't know why.
I just didn't feel like it.
I still tried to understandwhy that happened.
And at the age of like 18or something like that,
(36:16):
deciding to put a place likethat and go to a new college
was a risky decision,
not supported by many,
but I was not feelingat home at that place.
And then I wrote an examfor another institute,
undergrad institute, whichwas more research focused.
I qualified that exam.
(36:37):
So I went ahead joiningthe other institute
where I did a bachelor'sdegree in physics.
- And I really wanna asksomething here because
for those who mightnot know, I know Meenu,
you wrote such a really nice article
as part of this story,
"What is it like to bea woman in physics,"
which is a collection of stories
by women here at Perimeter Institute.
(36:57):
And I just wrote down oneof my favorite quotes.
You said,
it was not normal for a small town girl
from a conservative society like me
to leave home for undergraduate studies,
let alone later travelto a foreign country
for graduate studies.
And the rest of yourstory is really great too.
And I just was wondering
if you can kind of speakto that piece a little bit.
What was it like to make that decision
(37:19):
to challenge those societal norms?
- I was very scared inmy school time actually.
Like I was seeing most of the women
around struggling actually.
Like I have a bunch of likevery strong-headed women around
in my back in my family,or extended family,
but I still see that tryingto break any social norm.
(37:42):
Like they have to put so much effort.
And after putting in so mucheffort, little by little,
it breaks them down somewhere actually.
And that hard life that I was seeing,
all of them living,
I felt like I really needto have a better life,
which I can live on my own terms.
(38:04):
It was not normal for familiesback in those days actually
to send their girl,
girl child to study outsideof the hometown, actually.
It was not considered safe or something.
It's norm, it's relatively normal now.
But at, in those timesit was not that normal.
If I could crack thisprestigious exam called ITJ,
(38:26):
it was very prestigious
and it would be a prestige for the family.
They will be willing to sendme if I can crack this exam.
So I put in a lot of hard work and effort
and I was very, very scared.
What if I couldn't crack it?
Like I will be stuck here.
But with hard work, I think hard,
hard work and conviction,
(38:47):
I was able to crack thatexam and leave home.
So it was slightly difficult.
- And home, home is a relatively,
I think it's Gaia and India, Gaia.
- Yeah.- It's,
it's more of a tourist place.
I think it's a spiritual destination
because there's connections to Buddhism.
- Yes, that's right.- It's probably not a place
(39:07):
where a young girl saysI wanna be a physicist
and gets the warmest reception.
What kept you going whenthere, you said you,
you met opposition atstages along your way?
- First of all,
I really liked studying
and solving analyticalproblems in physics and math.
That was one thing.
And the other thing was like
that conviction that I want a better life.
(39:30):
So both of those things like,
and the third thing,
like I really got amazing teachers
like these coachingclasses I am telling about,
like I had three different teachers
who were extremelysupportive, always there.
Taking classes from themreally, really helped.
And they were there to answer my questions
(39:51):
or support me in any way they can.
So their presence meanta lot at that time,
actually their belief in me
that I can do something,I can crack this exam,
even though it is difficult,
that really helped.
Due to those factors,I was able to make it.
- And moving, you know,
from a small hometown to another city,
(40:12):
let alone a country on theother side of the world,
that was a big,
was that moving to Canada to do grad,
to do a PhD,
was that a,
a difficult leap for you to make
or was that always in the cards
that you would go somewhere to,
somewhere else to become a researcher?
- I don't exactly rememberwhen was the first time
(40:33):
I really thought that I couldgo to a different country
and live by myself and study on my own.
That was,
that was not something thatI thought from the beginning,
but then in my college,
like I was the third batch,
there were two more senior batches than me
and I was seeing other students,
including women, going out
(40:54):
to other countries for research projects,
summer internships orfor graduate studies.
And I just felt like ifthey could do it, I'll,
I'll be also able to do it.
So I followed their footsteps in that way.
So, yeah.
- And you created your own footsteps too,
you know, for others to follow.
- Yeah, hopefully
it will inspire others as well.
(41:15):
- It's interesting, right.
I think for so many people
it's so important to havethose role models, right?
Whether they be your colleaguesthat are a year ahead of you
or somebody that's maybealready a professional
in the field.
Was it important to you to have
role models at maybe differentlevels along the way?
- Yeah.
So my first role model Iwould say is Kalpana Chawla.
(41:36):
Unfortunately she is no more.
So Kalpana Chawla,
she was the first Indianwoman to go to moon,
actually during her second trip to moon,
there was a crash
in that shuttle and unfortunatelythey all passed away.
So yeah, she was a big role model for me.
(41:58):
Like she came from a small town
in another state in India,
which is Punjab,
and seeing her like reading her story,
knowing about her.
I felt like if I followed her footsteps,
I could do something as big as her.
(42:18):
So that was really important.
Looking back, I,
I can never think that Icould have looked up to Neil,
Neil Armstrong for example,
and thought that I couldhave done something similar
or something like that.
But having someone who has same gender,
same ethnicity, sameback family background,
like similar kind of family background.
(42:38):
And you can dream big
if you see some other people
with similar situation
dreaming big and being able to make it.
So in my childhood,
I always dreamed offbecoming an astronaut,
just like Kalpana Chawla,
changed over time.
But I think her presence
and whatever she achieved in her life,
(42:59):
knowing that helped me dreambig, at least in my life.
- Yeah, that's amazing.
- Amazing.
- Would you,
if someone offered youa chance to go to space,
now that space tourism is a thing,
would you wanna be an astronaut still?
- I think I'm less of a tourist
and more of a person from research.
Like if it was more of anopportunity to go there
(43:21):
from a research point of view,
I think I would be more interested
rather than just goingthere and seeing things,
how it looks like.
- If you did have to nowsay what's your dream,
what would it be?
Would it be to crack thisquantum classical correspondence?
- If I could play
good enough role intracking that question,
that would be really nice.
(43:42):
But apart from that,
like all these innovationshappening in quantum computing,
I keep on thinking to the day, like, it,
sometimes it seems like it is a big dream,
which may or may not happen.
But then I keep on thinking that
about the time when classicalcomputers were devised,
like the first computer
were like the size of a big room.
(44:02):
And now it's like in our hand.- Yeah.
And actually at the Institutefor Quantum Computing
where you were,
some of the quantum computers,
there are the size of a room.
It's, it's a,
it's a similar analogy there.- Yeah.
- Quantum computing is sortof at that infancy stage,
but you can see the,
the potential and yougot to work right in the,
in the middle of a quantumcomputing research center.
(44:24):
- Yes, that's right.- Well, I,
I love the way you put it earlier, too,
that sometimes doing research
involves putting together
so many little pieces of a puzzle, right.
And you have these pieces.
It's not always obvioushow they fit together
and it's not always obvioushow many pieces there are,
how long it's gonna taketo put them together.
But I think even figuringout how to glue together
two pieces is,
(44:46):
is a big accomplishmentin many cases, right.
- Yeah.
- I'm curious to know ifyou still have that same joy
that you felt when youwere a kid solving puzzles.
If doing math and solvingdifficult problems,
is it still fun?
Is it still like a hobby foryou the way it was as a child?
- Yeah, like whenever I get any new idea,
I'm very excited to try it out,
(45:07):
whether it'll work or not.
That's the most excitingpart of my research projects.
Like, and these ideasjust happen to come around
like while I'm doing some stuff,
which doesn't require a lotof attention, for example,
washing dishes or cookingor something like that, or,
or waiting at the bus stop for the bus.
So these are the moments when
(45:28):
some ideas will just come to my mind
and then I'm so excited to try it out,
whether that will work or not.
And that is the most joyous part of
being a researcher for me.
- Interesting, even ifit doesn't work out,
even if the idea fallsflat and doesn't pan out?
- So as long as a few ideasare working out out of many,
(45:50):
like as long as two or twoideas are working out out of 10,
suppose, that's fine.
It will be a little frustrating if
I thought of 10 ideasand nothing worked out.
(laughs)
But luckily,
if I think of 10 ideas,
two to three ideas turn out to work so.
- Trial and error only workswhen there's some error.
(46:11):
So yeah, you need to.- Yeah.
- Well, Meenu, we nowwanna take some questions
if that's okay.
So we, you know, as part of this,
we wanna see what otherpeople wanna ask you as well.
And so we have a question today
that was actually sent in by a student
from our PSI program hereat Perimeter Institute.
So for those that might not know,
PSI is a one year master'sprogram in theoretical physics
(46:32):
here at Perimeter Institute.
I actually teach in that program.
I teach lectures in quantumscience and machine learning.
So we have a question here
that's from one of ourstudents named Anna Kinur.
- What does it mean to do research
through the lens of quantum information?
Do you really think the world
can be reduced to only information?
(46:54):
- First of all, thanks alot, Anna, for that question.
That's a great question.
So the thing is in my research,
since I started my PhD,
I started working on quantum chaos
through the lens of quantum information.
So that has been a majorityof my part in my research.
So I can't really speak of a general term,
(47:15):
in general terms, what it means to
research and from other perspectives,
a lot.
The thing is quantum information,
I see it as something that has
brought together differentfields in physics,
like it has provided a newperspective in different fields.
For example, in condensedmatter to high energy physics,
(47:36):
which look like distinct topics, actually
in the first place.
Like if you go back like 30, 40 years ago,
all those physicists,
you can classify them ascondensed matter physicist
or high energy physicist.
But now that's not the case.
For example, I would talk about
a faculty here at Perimeter, Beni.
Like he works at so much, like he is,
(47:56):
he is very much into high.
- Beni Yoshida?- Yeah.
- We know Beni.- Jinx.
- Yeah, so he works very muchinto high energy physics,
like black holes stuff,
as well as condensed matter physics.
And he is a faculty
in the quantum information research group,
looking at things from thepoint of information perspective
gives us more pieces of the puzzle,
(48:18):
the bigger puzzle of physics actually.
And it definitely helps.
And maybe it'll be
piece that solves biggerproblems in physics, who knows.
- So it's not necessarily about
answering every possible question,
but giving a new way to lookat or a new perspective.
Yeah, oh, cool.
- To the existing problems,
other fields of physics actually.
(48:39):
So it's definitely an interesting way.
I have been working init for seven years now
since the start of my PhD
and I have really enjoyed it.
- I have a question fromsomeone named Ahmed,
a student here in Waterloo region,
and he asks why can't quantum mechanics
agree with relativity?
- Thanks, Ahmed for that question.
So thing is generallya theory of relativity,
(49:02):
space time is continuum.
Energy is also continuous,
but in quantum mechanics,
space time is at equal footing
in general related theory of relativity
and energy is a continuous thing.
But in quantum mechanics,
at least in the starting,
if we talk about the starting or picture,
space and time are at different footing,
plus energy is discreet.
(49:23):
It is quantized.
And other thing is like,
we still do not have aquantized period of gravity.
Like those pieces are required
such that we can glue together
general relativity and quantum physics.
- Is that quantum gravity that's--
- That's the bigger umbrella, yeah.
In which people are trying to figure out
(49:44):
how to quantize gravity
so that we will be able toglue together these two fields.
- So there's a whole field of research
devoted to answering thatquestion, I guess, yeah.
- Many faculties here, Iguess working in that area.
- Well Meenu, you've beenso generous with your time
and it's been reallyfascinating chatting with you.
Thank you for joining us.
It's been great.
- Yeah, thank you.
(50:04):
This has been just so much fun.
I've really enjoyedlearning more about you,
even though I've known you for years,
I've learned so much about you.
So thank you so much forsharing your time with us.
- Thanks a lot, Laurenand Colin, for having me.
(upbeat music)
- Thanks for steppinginside the Perimeter.
If you like, what you hear,
(50:25):
please help us spread the word.
You can rate,
review and subscribe
to "Conversations at the Perimeter"
wherever you get your podcast.
Every review really helps us a lot
and it helps more scienceenthusiasts find us.
Thank you for being part of the equation.
(upbeat music)
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