What is Bose Einstein Condensate

Have you heard of "Bose Einstein Condensate" but never really understood it? D&J break it down for you.

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Episode Transcript

Speaker 1 (00:08):
Hey, Jorney, do you know who is the first person
to reach the South Pole? It's probably a Norwegian, wasn't
it someone called rolled Emson. Yeah, he's pretty famous. But
do you know who the second or third place finishes were.
I'm gonna guess rold Emonson Jr. Or rold Emonson the third.

(00:30):
I have no idea. You know, those people who came
in second and third, they risked their lives, literally froze
their butts off, and we don't even know who they are.
Man in this case, it was literally a raised to
the bottom of the world. But yeah, you're right, I
guess second place doesn't get much attention. And the same
is true in science. There's no consolation prize for the Nobel.

(00:53):
You don't get a silver Noble price. They should hand
out a silver and a bronze, an honorable mention. There
just an honor to be nominated. Hi, I'm or Hamming

(01:17):
cartoonists and the creator of PhD comments. Hi I'm Daniel.
I'm a particle of physicist. And if I was in
the running for the Nobel Prize, I wouldn't get the
silver or le bronze. I would get the Plywood Nobel Prize.
You get the thanks for Trying coupon, I get the
pin and ribbon on him and say thanks. Welcome to
our podcast, Daniel and Jorge Explained the Universe, a production

(01:38):
of I Heart Radio in which we take a tour
of all the incredible things that scientists have won the
Nobel Prize for and dive deep into all the things
that science has not yet figured out, all the things
that people want to understand, all those weird mysteries of
the universe that nobody has yet figured out. Because it's
a big, mysterious universe out there and humans are trying

(02:01):
to make sense of it and come up with theories
about how it all works. But it is, after all
a human endeavor, and so it's about humans chipping away
at the big unknown questions of the universe. And here
on the show, we like to talk about the smallest things.
We like to break open the universe and find out
what it's made out of. What are the smallest things.
But another sort of orthogonal way to approach discovery is

(02:24):
trying to make matter do weird stuff like you're familiar
with three states of matter, solids, liquids in gases, But
it turns out there are lots of other really weird
things that matter can do. Yeah, there are other states
of matter like super hot forms like plasma, and also
super cold forms. And one of these forms is a

(02:47):
pretty well known form that we're going to talk about today.
That's right. If you get matter into really weird configurations,
it will do strange stuff. And this is a great
way to learn about what the rules are, how does
it fit together, what are the forces that are involved?
And it's just fun to make matter be weird. Can
you make it shinye? Can you make it jump? Can
you make it super conducting? Can you make it super fluid?

(03:09):
Can you make it act as a single blob? It's
fun to make new kinds of Google, would that be
your bumper sticker, Daniel? Keep matter weird, yeah, because one
of the basic ways to explore the universe is just
to look around you and see, like what kinds of
stuff is there? You know, the very first people to
think about what is the universe made out of just
sort of organized the stuff around them into like you know,

(03:30):
air or fire, earth and water. And that's reflection that
there are different kinds of things. And even though we
know that the universe has made fundamentally of tying the
little particles. Those particles come together in really weird ways.
I mean, who could predict solids and gases and all
sorts of weird behavior from just the tiny particles. It's complicated.

(03:51):
So while it's worthwhile to like dig down deep to
the tiny bits, it's also really worthwhile to figure out
how those bits play together to make weird stuff. So
to the the program will be asking the question, what
is a Bose Einstein condensate now? M Daniel, I'm guessing
that's not related to both speakers or being like a BOWS.

(04:17):
I think Bose was an early investor in the Bows
speaker system. They're not related. The Bose family fortune came
from physics. No, but they are related to the Higgs boson.
It's the same Bows, is it? Yeah? Yes, absolutely, the
Bose Einstein condensate is related to the Higgs boson. It's
the same. Bows is a famous Indian physicist whose last

(04:39):
name is Bose, and the kind of particle that we
call a boson, a particle of spin one, is named
after both. And he's also the guy who worked together
with Einstein to come up with this idea of a
weird state of matter called the Bose Einstein content. So
he did rocket leg a ball And I don't know
if you remember, but after the Higgs boson was discovered,

(05:00):
there are a lot of folks in India who are like, hey,
how come Higgs is getting all the credit? After all?
What about bos is important contribution? His name is half
of Higgs boson. Why isn't he getting as much credit? Wow?
I guess it's lots of brand appealed, like clean X. Yeah. Well,
if you're gonna get your name on stuff, you know,
you can get your name on one individual particle like Higgs,

(05:21):
or you can get your name on like a whole
class of particles like bosons. Bosons are anything with integer spin.
That's like half the particles out there, photons, w's, z
s all these are boson particles. Right. Well, so today
this is about states of matter, and you're right, it
is kind of interesting that, you know, we can talk
about what matter is and what it does and what

(05:43):
it looks like, but we can also talk about the
ways it can form itself or the ways that it
can exist out there. Yeah, and it's incredible that we
can sometimes predict this. We can just like write down
math on a piece of paper and say, we think
if you put these atoms in this weird configuration that
do this amazing, crazy thing you can't otherwise see. And
then it's a game of seeing whether you can do it.

(06:06):
You know, it's an experimental challenge. And this is one
of those stories where the theorists were decades and decades
ahead of the experimentalists. They had this idea in the
twenties and it wasn't until the nineties that people figured
it out. That means that it was one of these
like plums hanging out there where everybody knew if you
could be the first one to do it, you would

(06:27):
get a Nobel Prize. And there was sort of like,
you know, progress for ten years, and then things ground
to a halt. Nobody had any good ideas, and then
I burst a progress and then very late in the game,
a quick sprint to the finish line, where you know,
the people who crossed the finish line first, they win
the Nobel Prize and everybody else just has a cold
gas of atoms man. So only two people are famous,

(06:49):
the people who come up with a problem and the
people who solve the problem. Everyone in between gets forgot
that's right. And if you find this kind of story inspiring,
you know, there are plenty of other things out there
which everybody knows. If you discover them, you would win
a Nobel Prize. And maybe we're five years, maybe we're
fifty years away from discovering those things and somebody getting
the Nobel Prize. But there is plenty of low hanging

(07:11):
fruit left in physics. All right, are you making a
plug for bananas, Daniel, because they're pretty low hanging In general,
people have discovered bananas already, sorry to first bubble well,
such as the case for the Bose Einstein concent And
as usually, we were wondering how many people out there
knew what this was or where familiar with what the

(07:33):
state of matter is, And so as usual, Daniel went
out there into the wilds of the internet to ask
people what is a Bose Einstein concent That's right? And
if you'd like to participate in our random person on
the Internet questions, please write to us two questions at
Daniel and jorgean dot com. We would love to hear
your thoughts for future upcoming episodes. Here's what people had

(07:54):
to say. I would imagine something to do with Albert Einstein,
though I don't think it has anything to do with
Bose audio. I would guess it might have something to
do with Bosn's and condensate means, maybe something with the
way they behave at a particular temperature or pressure. Maybe
it's a speaker of the vibrates water out of the
year and then use the hydrogen to blow up your house. Well,

(08:18):
I heard about it, but I don't remember. It's some
kind of state or I don't know. I think Bose
was a fellow that was around before Einstein who came
up with the initial concept, and then I think Einstein
sweetened the deal a little bit. But this was around
something hectic to do with theory of relativity and the

(08:41):
expansion of the universe and universal constants, So I think
it was something related to that, but I can't quite remember.
I know it was mentioned on the podcast recently. It
was the state of matter, I think from dron The
scientists in the s S lab found it in some
udom cold lab that in the one name and they
discoded it's been theoretical so far, and so first them

(09:04):
there's something you exist in that state of matter? All right, Well,
it sounds like a lot of people knew was a
state of matter. Yeah, except for the folks who thought
it was a speaker that vibrates water out of the
air and blows up your house. Wow. Where did that
one come from? Right? I don't know. That must have
been like an awesome installation of massive bows speakers that
chattered somebody's windows or something, And I like somebody made

(09:28):
that connection to the Boson particle. Yeah, exactly. So there's
some good general knowledge out there. Good job listeners. Yeah,
so bose, Einstein, condensate, Daniel, let's dig into it. What
is it? I'm guessing it has something to do with
Einstein and maybe condensed milk? Is that the sweet and
condensed milk? Yes, it's a recipe for lemon bars by

(09:50):
Boz and only if you get it cold enough and
only the first bite. Yeah. So what it is is
a new state of matter, another state of matter different
and from liquid, solid, or gas or even plasma. And
as you said before, those are the states of matter
sort of organized in terms of temperature increasing, right, solid, liquid, gas, plasma.

(10:12):
And what happens there is the particles are disassociating as
they get hotter and hotter, they tend to move around more,
they have less restrictions. But there are these phase differences, right,
Things don't go smoothly from solid to liquid and liquid
to gas. They're these transitions where suddenly things behave different Wait,
isn't there a middle state called the smoothie or a

(10:35):
carbonated drink. That's right, it's called the margarita. That's the
state of matter you discover after you win the Nogo process. Right, Yeah,
it's made of dacorns. Now, So they're these interesting transitions,
and that's fascinating, right that these particles tend to work
in one way and then you cross them over a
threshold and they tend to work in another way, Like

(10:56):
there are different rules for gases and liquids and solids
and lasmas, right. And it has something to do with
the forces that bind atoms together and particles together, right, Like,
at some point their energy is more than the that bond,
and so they start arranging themselves in different ways exactly,
And so you have to understand it from the microscopic

(11:16):
You say, well, what's the dominant force? And just like
you said, when things get cold with the dominant force,
is this crystal structure of the atoms that are holding
them together. And after that, the dominant energetic contribution is
the kinetic energy of the objects. But there's still some bonds, right,
the bonds between atoms and a liquid or what give
you things like surface pressure and constant volume and stuff.

(11:39):
And so you have to understand, like what are the
dominant forces and how are they playing together? And so
you take these little atoms and you try to think
what are their emergent properties. And this is a really
hard thing to do, to go from the microscopic like
I have a few little particles to understanding the whole thing.
It's like why hurricanes are difficult. You know, we understand

(11:59):
how particles of water move through the atmosphere, it's not hard,
But how do you understand ten trillion of them swirling
around in really complex situations? So this kind of theory
is very difficult. And Bows and Einstein we're playing around
with the math and they figured out a new phase.
They're like, oh, here's a way if you arrange the
particles in this special way, you can get completely different

(12:21):
behavior from anything we've seen. Well, I guess you're saying
it's sort of like an emergent property that means that
it's like how they all behave collectively, and you're saying
that it doesn't you know, like you can't talk about
one atom being solid, liquid or gas, right, you have
to talk about like a collection of them, That's right.
You have to talk about the state of like many particles,

(12:41):
you know. I think about physics sort of like in layers. Right,
we have rules for how the solar system operates, and
we think about the planets as like an individual blob.
But then we also have rules for how winds move
and fluid dynamics, and then we have on another layer
we have rules for individual particles, and then deeper down
we have rules for like how the quarks move inside
those particles. That in principle, all you need to know

(13:04):
is the sort of lowest level stuff, the tiniest particles.
Those really do determine everything else. But in practice it's hard.
It's a hard way to do stuff, Like it's hard
to predict how a hurricane works, even if you understand
wind and water. And the amazing thing is how much
interesting stuff you discover that's not fundamental like tiny particles,

(13:26):
but comes out at the higher levels like hurricanes, And
this stuff can be simply described by new laws of
physics that work at that higher level, Like you don't
need to know about particles to understand how cannonball flies,
and have a math formula that describes it. And that's
why phases of matter are super fascinating, not because they're fundamental,

(13:47):
but because they emerge. All right, So then Einstein got
together with this scientist called Bows and they hung out
and worked out the math together. Or how did they
work together? I think Bo's actually worked out the basic
idea at first, and then Einstein reads paper and extended it,
and the result was this prediction that if you took
atoms and you made them not super hot like you

(14:08):
would need to get a plasma, but super duper duper cold,
then they would do something really interesting, but only if
there were a certain kind of particle, a particle called
a boson. Oh. I see, so this is not about atoms.
It's more like when we're talking about particular particles. Well,
there's two kinds of particles. There are fermions and there
are bosons. Fermions are particles that have a certain kind

(14:31):
of spin half an integer that can have spin one
half or minus one half, and bosons are particles that
have spin that are an integer. So they can have
spin like one zero or minus one. Now that's not
really a big deal, it doesn't really matter. But every atom,
for example, is either a fermion or boson depending on
how you build it up out of the little particles.
So for example, rubidium is a boson because of the

(14:53):
particles it's made out of. You can also have fermionic atoms. Oh,
what are electrons? But are electron? Electrons are emions, and
quarks are bosons. Right, Electrons are fermions and quarks are fermions.
At the particle level, the smallest level, all of the
matter particles quarks and leptons are fermions, while the force particles, photons, etcetera.

(15:14):
Are bosons. But you can combine fermions together to make boson.
So like two electrons together can make a bosonic pair
because the one has can add up to an integer.
And that's why, for example, you can make bosons out
of fermions. Some really complicated spin arithmetic there that we
probably don't want to get into. And vocabulary. I feel

(15:36):
like you're confusing me with vocabulary again, Daniel. But like Higgs,
boson then is made out of other things, or is
the higgs boson and boson bosons don't have to be
made the fermions. They can be fundamental like the higgs,
but all the force particles like the higgs, boson, the photon,
the w d z fundamentally are boson. But fermions can
get together and become like boson. Yes, absolutely, you can

(15:59):
combine find the half spin lego pieces to make integer
spin pieces. I see, but they have to come in
like in pairs. I guess right, Yeah, you have to
combine them the right way. So does it have to
do with like if the atom has an even number
of electrons or yes, exactly, so you can make bosons,
you can make fermions. Every atom can be fermions, you

(16:20):
can have bosons, etcetera. But there's an important difference because
bosons can do something that fermions cannot do, which is
hang out together. You're saying, yes, they can hang out together.
So fermions, for a reason that nobody really understands, can
never share a quantum state. Like that's the reason why
electrons which are fermions don't all lie in the ground

(16:42):
state of an atom, like you have an atom with
ten electrons in it. They don't all just lie in
the lowest energy level. They stack on top of each other.
The energy levels are a ladder. You can only have
one electron per layer of the ladder because their fermions
bosons are happy to all hang out at the bottom
level in the nuts. In many configurations, like you can
have a laser, which is a bunch of photons which

(17:04):
are bosons, all in the same quantum states. And so
we have two kinds of particles, bosons and fermions. And
we understand sort of mathematically why this happens. It emerges
from the math, but we don't really fundamentally and tutially
understand why bosons can all hang out in the same
state and formons just will not Like this, this famous

(17:25):
story about how somebody asked Fineman he find me, can
you explain this to us why bosons can all hang
out in the same state and formons can't. And he
came back and he said, you know, I don't have
an explanation that I can use on like eighteen year olds,
which means I don't really understand it. That's right. He's
famous for saying nobody understands quantum physics, right, yeah, exactly,

(17:48):
and you know it does come out of the mathematics,
but we don't intuitively understand it. It's just a weird
fact about the universe. But it means that if you
put a bunch of Boson particles together, they can in
all hang out in the coldest, lowest quantum state, and
that is the Einstein bos concit. Yes, so they predicted

(18:08):
that if you get a bunch of these particles together
and you get them really cold, they can all be
in the same quantum state. And then something really weird
would happen that because they would be so close together
and so cold that the size of their quantum wavelength
would be larger than the distance between them, and so
they would basically merge and all have the same quantum

(18:31):
state and act like one big quantum particle. Alright, cool,
let's get into it a little bit more and how
that all works. But first let's take a quick break.

(18:53):
All right, we're talking about the Bose Einstein condensate, and
you're saying that it's related to this idea that bosons
can hang out to other and they can share a
quantum state. I guess maybe some people might be wondering
what does that mean, Like they're sharing a quantum state.
Does that mean that they have all the same quantum
properties and are sitting in the same spot. It means
that they sit on top of each other. They can

(19:13):
be in the same location and they can share all
the same quantum properties. And this is really interesting because
usually you have just one particle in a quantum state,
and you know, we know the quantum state is sort
of a thing that controls what happens to one particle.
It's like a list of all the possibilities for what
that particle can do. But since you only ever have
one particle in a quantum state, you don't really see

(19:35):
the full distribution. But if you have a bunch of
particles and they're all in that same one quantum state,
then you can see sort of the whole distribution. You
can like physically look at this thing and see, oh,
here's the distribution of all the possible things that could
happen to this particle. Because you have ten million particles
and they're all in the same quantum states, you get

(19:57):
to see sort of all the outcomes at once. A
only if there are boson. Only if there are boson
because only bosons can do this. Permons can only have
one particle per quantum state. Bosons you can have any
number of particles all in the lowest quantum state. Now,
how do you get a bunch of particles in the
same quantum state. Well, the only way really to do
that is to push them up against the wall of temperature.

(20:19):
But you can't get them all in the same quantum
state if they're at two hundred degrees because there's a
billion different quantum states. So what you do is you
make them really really cold, so there's only one of
state available to them, the lowest one, and then they
all pile up in that quantum state. And Einstein and
Bows predicted that if you did that, you would get
this blob where the particles sort of lose their individuality.

(20:41):
They become a macroscopically size like you could see it
quantum mechanically behaving conject I guess maybe I'm getting tripped
up because I'm thinking of these things as particles. It's
like little things. But maybe you know, if you think
of them as waves, then it maybe makes more sense.
Like you know, fermions, you can't have a wave on
top of another wave, but bosons they're happy to stack

(21:02):
together as waves. It's that kind of what you're saying. Yeah,
And every time you think about these things, you should
not be thinking about a tiny, little spinning ball of matter, right,
because that's not what they are. They're weird quantum mechanical objects.
And the intuition you usually have about how a particle,
a little thing moves through space doesn't work. But you're right,
and you can apply that intuition to the waves because

(21:23):
the waves follow all those rules, like waves are deterministic
and their future can be predicted and actually move through space.
So yes, you can imagine all those bosonic waves sort
of stacking on top of each other. They're all doing
the same thing, right, whereas like a fermion, a bunch
of waves, they would all sort of avoid each other. Yeah, exactly,
like droplets that repel each other. Yeah, or sort of
like a game of connect for you know, you slide

(21:45):
the pieces in and they stack on top of each other,
and once you got one in a slot, you can't
get another one in a slot, whereas boson is that
just like slide right past each other, and they're all
happy to go down to the very lowest level. So
you couldn't play connect forward with bosons, they all stack
at the bottom. That would be a hard game to win.
There's right, unless it's connect one, in which case it's

(22:05):
over instantly, all right. So einstand and bos figured out
that if you cool atoms, you make them cold enough,
then with bosons then they all sort of like merge
together all their wave functions. I think you were telling
me that, like you go over some threshold, like their
quantum wave functions starts to overlap. The key thing is
to get them so cold. That's the size of their

(22:26):
wave function. The thing that controls where they are is
about the same as the mean difference in the spacing
between them, so that their wave functions actually overlaps. And
you have like atom number one over here and I'm
number two over there. They're not literally on top of
each other, but their wave functions are now over and
the more you can get them on top of each
other the better. But there's this sort of threshold where

(22:48):
their wave functions are now overlapping. And they think that's
when the faith transition occurs, and you get this new
weird kind of blob that should behave differently, and we'll
they can do exactly what this thing can do, but
it should behave differently than liquids or gases or solid Oh.
I see, it's kind of like normally the particles or
the atoms are are bouncing around, they're moving too fast,

(23:10):
really far apart from each other. But once you cool it,
they start to come together and at some point their
wave functions overlap. They synchronize. I guess is a good
way to put it. Yeah, they synchronize. They all follow
the same rules, they're all in the same state. They
can have different actual outcomes because remember there's still a
random element there, but they all have the same wave functions.

(23:30):
They're all determined by the same fundamental and dynamics. Wait,
there's like one overall wave function that sort of controls
all of them. Yeah, that's right. And you know, there's
nothing stopping you from writing a wave function down for
two particles that have nothing to do with each other.
But those way functions factorized. It's just like a product
of the two. But when they overlap, when they synchronize,
like you said, then you have a single wave function

(23:52):
that describes both particles. And so if you get a
bunch of particles you cool them, they will start to
overlap and suddenly it's like you have a giant article. Right,
that's kind of the idea, and that's they're all sort
of like moving together, but they're not really moving, they're
just sort of existing in a quantum way together. Yes,
and then together they can do quantum things that you

(24:12):
usually can only see on tiny microscopic particles. But now
you can see a giant, millimeter sized blob doing these
quantum things. A giant, like a millimeter sized quantum object.
That's yes, huge, that's huge. Yeah, I mean in a
literal and also significance. And it's not like it has
great you know, military applications or it's going to revolutionize

(24:35):
the Internet. You're not going to see like Bose Einstein
computing or whatever. It's mostly just cool, like, can we
make a new weird kind of Google, especially one that
reveals the fundamental quantum nature of the universe in a
way that's just totally unambiguous and observable. I guess because
you can look at it. Yeah, people like to see stuff,
and so here this is quantum mechanics you can see,

(24:56):
and so what kind of weird stuff can it do?
Can it's like teleport or well, it can interfere. So
you can have like two of these things with different
way functions, and then you sort of overlap them and
you see an interference pattern. Like rather than having a
single particle and it's got a probability going here or there,
you get these waves in the blob, You get these

(25:19):
interference patterns, these patterns of dark and light in the
single blob, and you can do quantum mechanical tunneling. Yeah,
that's what I mean by teleporting is that they can
cross impossible barrier. A single particle can have a way
function that exists on both sides of a barrier, right
like in a potential well, and across a barrier to
the other side of the well. So it can't be

(25:41):
in between, but has a possibility to be on the
left and the right. We did a whole fun podcast
episode about quantum tunneling and the reason that that can
happen is that the particle has a probability to be
on the left and the probability to be on the right.
And particles aren't limited to classical paths. They don't have
to go from where they were to where they are.
They just have these snap shots. So if your probability

(26:01):
to be on the left and then on the right later.
That's no problem. You can do that. That's quantum tunnel.
And so that's why would happen with the blob. It
would suddenly appear on the other side of a wall. Yeah,
you can have part of the blob on the left
and then suddenly have part of the blob on the right,
even though it can't go in between. So it can teleport.
So we can do weird. Yeah, quantum teleportation. Sure, So

(26:23):
you just have to be cool and you can teleport
super duper cool like nano cool. All right, And are
there any other interesting things that can do or interesting
applications we can use these for. Well, we talked about
this once that you can do weird stuff to light.
Bose Einstein condensate, because of its weird properties, can slow
down light to like the speed of a bicycle. Usually

(26:45):
light travels, you know, three hundred million meters per second,
but you can slow down light if it goes into
various media and boze Einstein content sates can slow it
down to like the speed of somebody riding a bicycle.
And there's a group of Harvor that even was able
to stop light inside of Bose Einstein condensate. Right, Yeah,
we talked about light going in and then bouncing around

(27:07):
kind of or interacting with the Bose Einstein concert and
essentially slowing down light. Yeah, slowing down light or even
stopping it. Like they can have a laser pulse go
into the Bose Einstein condensate and then they can just
wait and they can move it somewhere else and then
they can have it re emit the exact same laser pulse.
So that's kind of cool. They're working on using Bose
Einstein condensates to build an atom laser. So usually you

(27:30):
have a laser made of photons, right, You're shooting beams
of light made of tiny little photons. But people are
interested in shooting beams of atoms, atoms that are all
in the same quantum state, and that can do the
same kind of thing as a laser, like enhance and
resonate with each other. And it has all sorts of
weird applications. Plus it just seems kind of cool. And

(27:51):
so people are building atom lasers using Boze Einstein condensates.
That is a really weird thing that matter can do. Right,
I guess it's all because of quantum acount. It's like
you know, solid gas, liquid plasma. Those you can sort
of imagine from classical physics, right, but this one is
like a very unique quantum state of matter. Yeah, this

(28:12):
one you couldn't do if matter really was tiny little
classical balls. So you really need a microscopic quantum understanding
to make any sense of this. And it's sort of
awesome that they just use the map to predict it, right,
to say, like, oh, here's how we think this should work.
I'm really in all of those kinds of accomplishment. This
is a really interesting story. And so let's get into that.
Einstein and Bows figured out this possible quantum state of

(28:35):
matter and then it took seventy years to actually sort
of do it. Yeah, it took seventy years. And the
reason is that they knew it had to be really,
really cold. And so this basically just traces the technology
available to make stuff super duper cold. A story of
refrigerations what you're saying, Yeah, it's like the race to

(28:55):
the South Pole in that sense, right, It's a race
to the bottom of the temperature scale. How call did
it need to be? It needed to be down to
like nano kelvin, like really nano kelvins, like zero point
zero zero zero twelve zeros one kelvin. Yeah, And very
early on in the race, people were able to do
stuff like get down to a few degrees kelvin, you know,

(29:18):
tens of degrees kelvin, and you can do things like
super fluid helium, which we think now has a small
element of Bose Einstein condensate in it, but people really
wanted to get like a pure Bose Einstein condensate something
where most of the atoms were in that state, so
it was like unambiguous, and for that to happen, you
really have to get the whole thing down to really

(29:39):
really cold temperature, to nano kelvin. And so you're saying
then that even in the twenties and thirties they could
go down to a few kelvin, but I guess you
needed like a super special technology to go even further. Yeah,
And so fast forward to like the nineties, and people
have been trying to do this and using various techniques,
and you know, we had atomic physics and you could
trap individual a ms and do clever stuff. But people

(30:02):
were struggling, right, they sort of hit a wall, and
there was a lab at m I T that was
trying to use hydrogen. They're like, let's just start with hydrogen.
And this is Dan Kletner his lab at m I T.
And he sort of hit a wall in the nineties
and couldn't really make much more progress. But that's when
the breakthrough happened. He couldn't teleport to the other side. Yeah.
Then people made two really big advances, and there's actually

(30:25):
his students that made these advances. Two advances were laser
cooling and magnetic evaporation. Is the two technologies that let
them super cool these atoms down to the levels they
need to. All great combinations of words that you sound
impressive in the physics sense, magnetic evaporation and laser cooling.

(30:46):
All right, let's get into the details of how they
finally found a Bose Einstein concert and let's talk about
what awesome things we can do with it. But first
let's take another quick break. Okay, So there's a raise

(31:10):
Daniel to get the coldest thing possible so that it
can snap into the Bose Einstein state of matter, conside,
and so they figured out how to do magnetic evaporation
to do that. What does that mean. What that means
is you have a bunch of atoms and you want
to get it colder. How do you do that? Well,
one way is to actually make all the atoms each

(31:32):
individually slow down. Another way is to just sort of
take out its kinetic energy. Yeah, because remember temperature is
basically kinetic energy. The faster these things are moving, the
hotter the gas is. The Other way to do it
is to start with a larger sample and then just
pick out the slower moving ones, like boil off the
hot parts. Selectively pick out the slow ones. Then you

(31:56):
end up with somebody which is on average colder than
what you started, right. That's kind of what happens to
a glass of water when you leave it out right,
Like it's actually a little bit cooler than ambient temperature
because all the hot water atoms fly off. Yeah, I
think that's true. Where it's sort of like you know,
say you had a glass of ice water and you
wanted it colder. Well, one thing you do is put
it in the freezer and actually cool it all down.

(32:17):
The other thing is you could just fish the ice
out of it and be like, oh look now I
have ice, right, and you just leave the hot parts behind.
So magnetic evaporations sort of works like that. It says,
let's just pick out the coldest bits, so start with
more than your need, right, and has a distribution. Some
are hot, some are cold, and you pick out the
cold bits. In the way they do it is they

(32:38):
put it in a magnetic bowl. So they put it
in a bowl so that you need to have enough
energy to get out of the bowl, and you just
let it sit there for a little while and the
hot ones will get over the lip of the bowl
and the cold ones will get stuck in the bottom,
and eventually you're left with only the cold one. Gradually
lower the sides of the bowl and so they can
tune the temperature that they get. Well, so that's one

(33:00):
way to cool example. And then you also said they
can use lasers. Yeah, they use lasers. And this is
sort of mind blowing because you imagine, if you're gonna
cool something down, you probably shouldn't shoot it with high
energy lasers, right, So this is really counted to it if.
I don't know how anybody came up with this idea,
but the way it works is that you shoot a
laser at these atoms and you shoot a laser at

(33:20):
them at just above the energy that they like to absorb. Remember,
adams can't just absorb any photon. They have to absorb
photons of certain energies to have this spectrum that they
can jump up and down to. So they need a
photon that has exactly the right gap between the energy
level they're at and the one they can go to.
So if you shine an arbitrary energy laser through a gas,

(33:43):
probably won't even absorb anything. You have to sort of
tune the laser to where the gas likes to drink
its light. But wouldn't that make it absorbed then the light,
how does that make it give off energy? So what
they do is they tune the laser to just above
where it likes to absorb the light. And what this
means is that atoms moving towards the laser, we'll see

(34:05):
the laser doppler shifted. It will change the wavelength of
the light to be the one that they like to absorb.
So adams moving towards the laser will preferentially absorb this
laser light, which will slow them down because they're moving
towards the laser. So you pick the ones that are
moving towards the light and you give them a push
and that basically slows them down a little. And then

(34:26):
the opposite happens for the atoms going the other way. Yes,
and so what you do is you shoot laser beams
at this thing slightly above the wavelength that they should absorb,
and that preferentially slows down the atoms moving away from
the center of the block. It's like a quantum hack.
It's really cool. It's mind blowing. And you know, they
do absorb this and then they give off the light

(34:48):
and so they slow back down, but they end up
going in a different direction. And so you've taken a
particle which was shooting towards the laser and you've modified
its angle a little bit, and that in effect slows
it down because the overall magnitude of its philosophy is
now smaller. I see. It's kind of like a wall
that slows and Adam down, but only in one direction. Yeah.
It's like you've got a bunch of sheep and you've got,

(35:08):
you know, a dog on each side, and it's like
finding the single sheep that are running away from the
herd and sort of like turning them around and pushing
them back in, and eventually sheep come together and make
a Bose Einstein content sheep. That's such a bad joke, Danny.
All right. So the race was on to be the
coolest physicist on the planet to get the Bose Einstein

(35:30):
contestant going. And we were at M I T and
then somebody discovered these two techniques. Yes, so Dan Kleptner
was doing it at hydrogen with M I T but
sort of hit a wall. And then his students went
out to NIST into you See Boulder and they started
a lab out there. These are Cornell and Wyman. I
believe it's See You Boulder. Then I just want to

(35:51):
insult the whole campus as people. Thank you. Yeah, I'm
biased because I'm at the Universe of Californ in this,
I think, you see. And they had an idea to
try heavier out of instead of using hydrogen, which had
this certain interaction between them that made it hard for
them to stay in the magnetic trap. They said, well,
let's use rubidium. Rubidium is still a boson, but it's
a little heavier. And so people hadn't tried these heavier

(36:14):
alkali atoms before, and so they made a better magnetic trap,
and they had this cool idea to use really cheap lasers,
like other folks were trying to get their lasers to
work and buying like a hundred and fifty dollar laser systems.
But you know, this is the era when you could
buy like a laser for two dollars because they were
in CD players right in DVD readers, laser pointers and

(36:36):
laser pointers. So lasers have become really cheap. And they
figured out a way to use really cheap lasers and
that combine them in this cool way to make it
very flexible but very powerful. So there's sort of like
this experimental cleverness and they were the first ones to
do it. They combined this magnetic evaporation with this laser
cooling and it was in that they were able to

(36:58):
get this thing down to a d seventy nano kelvin
and they actually saw this Bose Einstein condensate in their device.
What did it look like like? Does it look like
a blog? Yeah, it looks like a blog. Can you
actually see it or is it too small? You can
actually see it? It looks like a blob. It's like
millimeters across. It lasted for about fifteen seconds. It had

(37:19):
like two thousand atoms in it. And you know what
happens is it's getting colder and colder and colder, and
each atom is sort of doing its own thing. And
when you have a bunch of atoms doing their own thing,
you get like a distribution, like some are a little faster,
some a little slower. All of a sudden, when they
crossed this threshold, this temperature threshold, they all snapped into place,
and we're all doing the same thing. Like they all

(37:40):
had the same velocity and they were in the same place,
and they acted like one mega particle. And you can
see this in their paper. They show like there's a blob,
there's a blob boom, there's a spike in the middle,
and that's a phase transition. That's when matters like doing
something really different. That's when it clicks. That's when it clicks. Yeah.
The sort of tragic thing is that you and see it,

(38:00):
but the only way to see it is to shine
a laser at it. Right, this is really small and
really cold, can just like see it with your naked eye.
So they had to shine a laser at it, which
destroys it. So they can prove that it's there, but
only by destroying And is that why it only last
fifteen seconds because you're trying to look at it at
the same time, or what's the time limit here? The
time limb is just how long they can keep this

(38:21):
thing cold and trapped. Eventually the atoms will fall out
of their trap. And the way they made their magnetic
bowl has a bit of a hole in the bottom
they had, so they were struggling with that a little bit,
and so it's hard for them to get a lot
of atoms in there and for it to last a
long time. It's a leaky bowl, a little bit of
a leaky bowl. But hey, they were the first ones
to do it. Because at m I T there was

(38:42):
a follow up lab, a lab led by Wolfgang Keaderly
that was sort of inheriting what Kleppner had done and
also trying to use heavier atoms. And there was a
race between this lab at U C Boulder and this
lab at M I T, and then also a lab
at Rice University, where I was happening to be an
undergraduate at this very moment, right you're telling me you
knew one of the scientists in this race trying to

(39:04):
get it to work first. Yeah, so everybody sort of
figured this out, and everybody knew that like this was
going to happen, and it was going to happen soon. Really,
like everyone knew that they were close to the finish
because they'd be giving presentations at conferences and these ideas
have been sort of coalescing, and these guys were the
leaders in the field, and it was really about like
making it work and getting it done. So the ideas

(39:24):
were out there, everybody knew how to do it. There
are a few slightly different approaches, like the guys that
m I T had a cool way to plug the
hole in the bottom of their magnetic well using another laser,
and the guys at Rice course, and the guys at
Rice were using lithium to try to get it done.
And I remember at this time because I was taking
thermodynamics as a physics major and the person teaching it

(39:47):
was Professor Randy Hewlett, and he was engaged in this
three way race for the Nobel Prize. These three labs
were all trying to make this happen at the same time.
I remember specifically because he almost never showed up to class,
like he was off giving talks, or he was in
the lab, or he sent his grad student or canceled lecture.
At the time, I was like, what is this guy
doing these things? He's so important. He was racing to

(40:10):
get the Nobel Prize. He wasn't on the clock. He
was on the clock where you know, days and weeks
make a difference between winning the Nobel Prize and just
being like also mentioned on the podcast years later by
one of your students that you ignored. Oh no, but
if the people at T Boulder did it first, who

(40:31):
got the Nobel Prize? We'll see you Boulder did it first.
And then M I T did it a couple of
months later, and they put out their paper. I think
this is so M I T. They put out their
paper the Monday after Thanksgiving, which means they must have
worked all Thanksgiving. Break them. Yeah, it was a few
months later, but it was a lot bigger, Like they
plugged that hole and they were able to get a

(40:53):
lot of atoms like you know, many many more atoms
that lasted a lot longer than to see you Boulder one.
So it was really like a big step forward in
another demonstration, and then you know, Rice did it also
in lithium. But it was later, and so they didn't
get included in the Nobel Prize. They went to MT
and see you Boulder, but Rice just got a cold gas. Well,

(41:16):
but Rice did it. They just did it even later,
and so the Nobel price compantee said, all right, we'll
cut it off at a couple of months after the discovery.
That kind of it seems a little totally arbitrary, but
there is this rule about Nobel Prizes you can only
share it among three people. And so there are two
p I s leading the lab at SEU Boulder slash
Mist and one leading the lab at m I T

(41:37):
And so that was sort of a natural cut off. Yeah, man,
you know, so you know, if those grad students in
the lab at Rice had just worked over Thanksgiving or
giving up their Christmas break or not taking vacation, or
if they didn't have to teach your class, maybe they
didn't have to grade. Like, oh, I almost got it,
but I gotta go teach this freshman the physics class.

(41:57):
I gotta grade this sloppy homework. May in I can't
even read this, writing up all night trying to decide
for this kid's homework. So basically, Daniel you're claimed to fame.
Is that not only did you know the second place
finisher for the both iceland concept, you were maybe a
participant slowing this person down. I definitely had interactions with
this person. No. I I know Randy Hewlett. He's a

(42:20):
great physicist and I admire him, and he's a great teacher,
and I think it's exciting to be on the forefront
and so close to the cutting edge. I do have
some sympathy for being so close and not quite being
included in the upper echelon of folks who win the
Nobel Prize. Yeah, I mean it seems kind of arbitrary, right,
Like you get the Nobel Prize, you don't get the prize,
but they were all sort of in it together. Yeah,

(42:41):
And what's really the difference between a few months here
or there. I think a lot of times people in
science make way too big a deal about somebody who's
one day ahead or the second day. You know, it's
important that everybody has done their own individual work. If
somebody has published a result and you just go and
replicate it, that's not the same thing as individual independent
in contribution. These are different lines of research, different ideas,

(43:03):
different strategies, really independent efforts that were in parallel. Sure,
one finished a few weeks or months ahead of the other,
but they all made contributions around the same time. So
in a better world, we would have recognized all of
them and think about his accomplishments. I mean, he taught you,
and now here you are teaching thousands and thousands and
thousands of people. Yeah, that's a I hope that's enough

(43:24):
for you. You didn't get to meet the King of Sweden.
You got to be talked about on my podcast. All right,
Well that was pretty exciting for such a cool topic,
such a chill topic. Yeah, and so people are continuing
and now they make Bose Einstein condensates all the time.
They even made it once on the space station, kidding like,
you can make a Bose Einstein maker that you can

(43:46):
take to space. Yeah, exactly. They put together a lab
on the International Space Station that made a Bose Einstein
condensate in space, which is pretty cool. Could they also
make bar garded and smooth only on Fridays? Very cool
that Bose and Einstein thought of this and that it
actually came to pass. That's pretty awesome. And now it
gives us a new window, a new kind of stuff

(44:07):
to poke and to play with. And you know, now
we can make these things and they last a long time,
so you can do things like stir them and make
vortices in them, and watch quantum vortices be created and
overlap them and and launch them into each other, and
see interference effects on macroscopic objects. So you can recreate
a lot of the cool quantum mechanical experiments that used

(44:28):
to only work on tiny, invisible microscopic particles. Now you
can do them on macroscopic blobs of stuff. That's pretty amazing.
So are there any other states of matter we should
be looking out for or that we might discover in
the future. You know, there are lots of other states
of matter that people theorize about, you know, tetracorks and
hexa corks and all sorts of weird combinations. Because matter

(44:49):
is complex and it has lots of really complicated interactions
and in various configurations and pressure and density. You know,
you can do all sorts of weird stuff, like we
talked about quirk matter and strang age matter. You know,
what might happen in the core of a neutron star.
And I'm sure there are lots of things we haven't
even imagined. One day, I hope we'll discover something before
we think about it, so we'll have a triumph for

(45:10):
experimental physics rather than just for theoretical physics. Well, and
maybe somebody out there listening could be the person to
discover this new state of matter. That's right. There's lots
more to discover, lots more weird kinds of good that
we can make matter to do. And hopefully you'll start
a lab and zap matter into doing something weird and
then chill out with your Nobel Prize and your Margarita

(45:33):
or at or your silver Bibel Prize. What did you
call it, the Plywood Nobel Prize? Plywood not as valuable,
but very tough. It's very hearty, that's right. Yeah, and
it's got the description written in a sharpie. All right. Well,
we hope you enjoyed that, and you we hope that
you joined this amazing race to discover new kinds of matter.

(45:55):
And thanks for listening. If you're interested in hearing more
about this kind of stuff, please send us a suggestion
two questions at Daniel and Jorge dot com and come
interact with us. We're on Twitter at Dale and Jorge
where we answer questions and make jokes, so come and
check us out. Thanks for joining us, see you next time.

(46:19):
Thanks for listening, and remember that Daniel and Jorge explained.
The Universe is a production of I Heart Radio. Or
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