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The Quantum Sensor That Could Find Dark Matter · The Quark Side - Quantum Physics Podcast

• 0:01
  Speaker 1: Welcome to the quart Side Quantum Physics Podcast, an exploration
• 0:05
  Speaker 1: of the fundamental structure of reality where quantum laws govern matter, energy,
• 0:11
  Speaker 1: and information. Here, uncertainty is a feature, not a flaw,
• 0:16
  Speaker 1: and understanding begins at the smallest scales.
• 0:27
  Speaker 2: What if the biggest, the most incredibly violent events in
• 0:33
  Speaker 2: the entire history of the universe are echoing through your
• 0:36
  Speaker 2: body right now?
• 0:37
  Speaker 3: It is a wild thought.
• 0:38
  Speaker 2: Yeah, right, Like, somewhere out in the unfathomable stretches of
• 0:42
  Speaker 2: the cosmos, maybe billions of years ago, two ancient black.
• 0:47
  Speaker 3: Holes collided, an event so cataclysmic that it actually warped
• 0:51
  Speaker 3: the underlying geometry of space and time.
• 0:53
  Speaker 2: Exactly, and that collision sent gravitational ripples out into the void,
• 0:58
  Speaker 2: traveling the speed of light for ea. And right now,
• 1:01
  Speaker 2: as you are listening to this, those whipples are passing
• 1:04
  Speaker 2: through the room you are sitting in.
• 1:05
  Speaker 3: They're passing right through the chair, supporting.
• 1:07
  Speaker 2: You, literally stretching and squeezing the atoms in your body.
• 1:10
  Speaker 2: And it's happening constantly. The universe is vibrating right through us.
• 1:13
  Speaker 2: But we just you know, we haven't had the capacity
• 1:15
  Speaker 2: to perceive it.
• 1:16
  Speaker 3: We really haven't. It forces a complete recalibration of how
• 1:19
  Speaker 3: we perceive reality. Honestly, we navigate our daily lives feeling anchored,
• 1:23
  Speaker 3: assuming the space we occupy as a rigid, empty.
• 1:26
  Speaker 2: Container, right, like a solid stage exactly.
• 1:28
  Speaker 3: But space time is a dynamic, fluid medium.
• 1:31
  Speaker 2: It rings, it rings. Wow.
• 1:34
  Speaker 3: Yeah. The reason we don't feel a supermassive black hole
• 1:37
  Speaker 3: merger physically tearing us apart is that the amplitude of
• 1:40
  Speaker 3: that wave well by the time it reaches Earth has
• 1:43
  Speaker 3: decayed to a scale that completely mocks human intuition.
• 1:48
  Speaker 2: How small are we talking.
• 1:49
  Speaker 3: We are talking about a fractional change in distance, equivalent
• 1:53
  Speaker 3: to shifting the distance between the Earth and the Sun
• 1:55
  Speaker 3: by the width of a single atom.
• 1:57
  Speaker 2: Okay, let's impact This a fractional change of atom over
• 2:00
  Speaker 2: millions of miles. To try and capture something dat subtle
• 2:03
  Speaker 2: sounds honestly like a fool's.
• 2:05
  Speaker 3: Errand it does. It sounds impossible.
• 2:07
  Speaker 2: But in our deep dog today we're looking at how
• 2:09
  Speaker 2: that impossible ceiling was just shattered. On July seventh, twenty
• 2:14
  Speaker 2: twenty six, a paper published in the journal Nature completely
• 2:18
  Speaker 2: changed what we thought was physically measurable.
• 2:20
  Speaker 3: A monumental shift.
• 2:22
  Speaker 2: A team of physicists at Imperial College London successfully demonstrated
• 2:26
  Speaker 2: a prototype quantum sensor using ultra coold strontium eighty seven atoms.
• 2:31
  Speaker 3: Which is a very specific, very important choice of element.
• 2:34
  Speaker 2: Yes, right, and we'll get into that. But they deployed
• 2:37
  Speaker 2: this noise canceling technique that strips away the inherent quantum
• 2:40
  Speaker 2: jitter of our own instruments.
• 2:42
  Speaker 3: And this isn't just an incremental step in laboratory physics.
• 2:45
  Speaker 3: I mean this is a mechanism that could finally allow
• 2:48
  Speaker 3: us to map the primordial gravitational waves from the.
• 2:51
  Speaker 2: Big Bang and directly detect the dark matter holding the
• 2:56
  Speaker 2: universe together. It is huge.
• 2:57
  Speaker 3: The magnitude of the Imperial College break through really requires
• 3:01
  Speaker 3: us to first confront the limits of our current astrophysics.
• 3:04
  Speaker 2: Yeah, set the stage for.
• 3:05
  Speaker 3: Us, well, everything we have ever cataloged, every star, nebula,
• 3:09
  Speaker 3: galaxy observed by Hubble, James Webb or terrestrial radio arrays,
• 3:15
  Speaker 3: that constitutes roughly five percent of the mass energy content
• 3:19
  Speaker 3: of the universe.
• 3:20
  Speaker 2: Five percent. That is just staggering.
• 3:23
  Speaker 3: The rest is entirely missing from our visual registry. So
• 3:26
  Speaker 3: imagine standing in a massive pitch black room. You know,
• 3:30
  Speaker 3: for a certainty there are unseen leviathans moving around you
• 3:33
  Speaker 3: because you can feel their gravitational displacement.
• 3:36
  Speaker 2: You feel the breeze as they walk by precisely.
• 3:38
  Speaker 3: But they emit no light, they reflect no light, and
• 3:41
  Speaker 3: they block no light.
• 3:42
  Speaker 2: So you're just standing there in the dark.
• 3:44
  Speaker 3: Right, And the workout of the ultra cold Strontium Laboratory
• 3:47
  Speaker 3: is the theoretical and practical foundation for a switch that
• 3:51
  Speaker 3: will eventually illuminate that room.
• 3:53
  Speaker 2: So to understand the machine, I think we first need
• 3:56
  Speaker 2: to understand the leviathans. Let's start with dark matter, because
• 4:00
  Speaker 2: it has been the ghost haunting cosmology for what nearly
• 4:04
  Speaker 2: a century just about. Yeah, we see the gravitational effects,
• 4:07
  Speaker 2: like the rotational speed of galaxies holding together when they
• 4:10
  Speaker 2: should fly apart. But what exactly is the Imperial team
• 4:13
  Speaker 2: looking for here? Because they aren't looking for like massive
• 4:17
  Speaker 2: black holes acting as dark matter, right, they are hunting
• 4:20
  Speaker 2: for exotic forms.
• 4:22
  Speaker 1: Right.
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  Speaker 3: We have to look at the historical failure of certain
• 4:25
  Speaker 3: dark matter models to understand why this quantum sensor is
• 4:28
  Speaker 3: so vital. The old models, Yes, for decades, the leading
• 4:31
  Speaker 3: candidates for dark matter were.
• 4:32
  Speaker 2: Whimps, weakly interacting massive.
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  Speaker 3: Particles exactly the assumption was that dark matter was a
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  Speaker 3: particle much heavier than a proton that only interacted via
• 4:41
  Speaker 3: gravity and the weak nuclear force, like.
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  Speaker 2: A heavy, invisible billiard bawl.
• 4:45
  Speaker 3: Right, so we built massive subterranean vats of liquid xenon,
• 4:50
  Speaker 3: hoping a wimp would occasionally strike as xenon nucleus and
• 4:54
  Speaker 3: produce a tiny flash of light. But year after year
• 4:56
  Speaker 3: those detectors have remained largely silent. Diaminter space for whimps
• 5:01
  Speaker 3: is shrinking rapidly, so.
• 5:03
  Speaker 2: The physics community is pivoting. If it's not a heavy
• 5:06
  Speaker 2: particle bumping into things like a billiard ball, what is
• 5:09
  Speaker 2: the alternative?
• 5:11
  Speaker 3: The alternative takes us into the realm of ultra light bosons,
• 5:14
  Speaker 3: things like axions or dark photons.
• 5:17
  Speaker 2: Dark photons sounds like sci fi.
• 5:20
  Speaker 3: It really does. In these models, dark matter is so
• 5:23
  Speaker 3: incredibly light that you can't even think of it as
• 5:25
  Speaker 3: a discrete particle anymore.
• 5:26
  Speaker 2: Because of wave particle duality.
• 5:28
  Speaker 3: Right, exactly, because of wave particle duality and quantum mechanics,
• 5:31
  Speaker 3: a particle with an infinitesimally small mass has an incredibly
• 5:35
  Speaker 3: long wavelength. If dark matter is an ultralight boson, its
• 5:39
  Speaker 3: wavelength could be the size of a dwarf galaxy.
• 5:42
  Speaker 2: Wow, Meaning it's not a swarm of tiny bullets hitting us.
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  Speaker 2: It's an oscillating background field. We're basically swimming in an
• 5:49
  Speaker 2: invisible ocean that is sloshing back and forth at a
• 5:52
  Speaker 2: specific frequency.
• 5:53
  Speaker 3: That's a perfect way to visualize it. And the mathematics
• 5:56
  Speaker 3: of these ultra light fields suggests something profound. They might
• 6:00
  Speaker 3: interact with normal matter, not by bumping into it, but
• 6:03
  Speaker 3: by altering the fundamental constants of nature.
• 6:06
  Speaker 2: Wait, altering the constant.
• 6:08
  Speaker 3: Yes, if an ultra light dark matter wave washes over
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  Speaker 3: the Earth, it could momentarily change the mass of an
• 6:15
  Speaker 3: electron you're kidding no, Or it could subtly alter the
• 6:18
  Speaker 3: fine structure constant, which dictates the strength of the electromagnetic interaction.
• 6:23
  Speaker 2: So if the fine structure constant changes, the energy levels
• 6:27
  Speaker 2: of every atom on Earth would shift.
• 6:29
  Speaker 3: They would.
• 6:29
  Speaker 2: The atoms would essentially breathe yea, expanding and contracting microscopically
• 6:34
  Speaker 2: in time with the dark matter wave.
• 6:36
  Speaker 3: Exactly they breathe. The energy required for an electron to
• 6:39
  Speaker 3: jump from one orbit to another.
• 6:41
  Speaker 2: Would oscillate, but it would be tiny, oh.
• 6:43
  Speaker 3: Incredibly subtle, completely invisible to standard chemistry or physical observations.
• 6:49
  Speaker 3: You need a device capable of interrogating the internal state
• 6:52
  Speaker 3: of an atom with terrifying precision.
• 6:54
  Speaker 2: You need a quantum ruler.
• 6:55
  Speaker 3: You need a quantum ruler.
• 6:56
  Speaker 2: Which perfectly bridges to the second Leviathan in the which
• 7:01
  Speaker 2: is ancient gravitational waves. Because the ruler required to measure
• 7:05
  Speaker 2: atomic breathing is the exact same ruler required to measure
• 7:08
  Speaker 2: the stretching of space itself.
• 7:10
  Speaker 3: It's the exact same technology.
• 7:11
  Speaker 2: Yes, but I want to pause here because I can
• 7:14
  Speaker 2: hear the immediate objection from anyone who follows astronomy. We
• 7:17
  Speaker 2: already found gravitational waves. Right in twenty fifteen, Ligo detected
• 7:23
  Speaker 2: the collision of two black holes. It literally won the
• 7:26
  Speaker 2: Nobel Prize. We built these massive l shaped vacuum tubes
• 7:31
  Speaker 2: four kilometers long, balanced lasers down them, and watched the
• 7:35
  Speaker 2: interference pattern change when the wave passed.
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  Speaker 3: A monumental achievement.
• 7:39
  Speaker 2: So if LIGO already has the Nobel Prize, why do
• 7:41
  Speaker 2: we need tiny atoms to do the exact same thing.
• 7:43
  Speaker 3: Well, Logo is a triumph of human engineering, but it
• 7:46
  Speaker 3: is fundamentally limited by the macroscopic world. Ligo is essentially
• 7:50
  Speaker 3: a giant Michaelson interferometer. Right. It relies on physical test
• 7:54
  Speaker 3: masses massive mirrors suspended by ultrapure feu silica threads. When
• 7:59
  Speaker 3: a gravitational wave pas, it moves those physical mirrors.
• 8:02
  Speaker 2: It physically pushes them.
• 8:03
  Speaker 3: Yes, but because those mirrors are macroscopic objects on Earth,
• 8:07
  Speaker 3: they are subject to planetary noise. LIGO is tuned to
• 8:11
  Speaker 3: hear the high frequency chirps of stellar mass black holes merging.
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  Speaker 2: Events that produce waves oscillating between what ten and one
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  Speaker 2: thousand times a second roughly, Yes, the audio band. I
• 8:22
  Speaker 2: remember reading that if we converted Ligo's data to sound,
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  Speaker 2: it literally sounds like a bird chirping.
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  Speaker 3: It does. But the most profound events in the universe
• 8:31
  Speaker 3: do not happen quickly like what like when two super
• 8:34
  Speaker 3: massive black holes at the center of colliding galaxies merge.
• 8:38
  Speaker 3: They are millions of times more massive than the Sun.
• 8:41
  Speaker 3: They orbit each other for thousands of years before finally colliding.
• 8:44
  Speaker 2: Thousands of years.
• 8:45
  Speaker 3: Yes, the gravitational waves they emit have a frequency in
• 8:48
  Speaker 3: the millihertz or Microhurtz range. A single wavecrest might take
• 8:53
  Speaker 3: hours or days to pass through the Earth. Wow, there
• 8:55
  Speaker 3: is also the stochastic gravitational wave background.
• 8:58
  Speaker 2: The ambient rumble of basetime ripples left over from cosmic inflation, right,
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  Speaker 2: just fractions of a second after the Big Bang itself.
• 9:05
  Speaker 2: So why can't LIGO just listen longer if it's a
• 9:09
  Speaker 2: slow wave, just record the data for a few days
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  Speaker 2: instead of a few seconds.
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  Speaker 3: Because of a physical barrier known as the seismic wall,
• 9:17
  Speaker 3: and something even more insidious, which is Newtonian gravity.
• 9:21
  Speaker 2: Noise Eutonian gravity noise.
• 9:23
  Speaker 3: Yes, below about ten hertz, the Earth is milently noisy.
• 9:28
  Speaker 3: The oceans beating against the continental shelves create micro seismic vibrations.
• 9:33
  Speaker 2: Just the waves hitting the beach, Yes.
• 9:35
  Speaker 3: It shakes the entire continent enough to mess up the mirrors.
• 9:38
  Speaker 3: The wind hitting the facility creates noise. You can suspend
• 9:42
  Speaker 3: a mirror on the most advanced pendulum system ever conceived,
• 9:45
  Speaker 3: but you cannot shield it from gravity. What do you
• 9:48
  Speaker 3: mean If a dense rain cloud passes over the Lago
• 9:50
  Speaker 3: facility in Washington State, the gravitational pull of the water
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  Speaker 3: in that cloud physically pulls on the mirror.
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  Speaker 2: Wait, really, a rain cloud pulls the mirror.
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  Speaker 3: The mass of the water ex so it's a gravitational
• 10:00
  Speaker 3: force the mirror moves.
• 10:02
  Speaker 2: That is insane.
• 10:03
  Speaker 3: You cannot build a shield against gravity. That is a
• 10:05
  Speaker 3: fundamental rule of general relativity.
• 10:07
  Speaker 2: So a rain cloud or I don't know, a truck
• 10:10
  Speaker 2: driving a mile away displacing dirt creates a localized gravity fluctuation. Yeah, exactly,
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  Speaker 2: and that completely drowns out the slow, subtle stretch of
• 10:19
  Speaker 2: a primordial gravitational wave. The detector is just overwhelmed by
• 10:24
  Speaker 2: the sheer chaos of existing on a geologically active atmospheric planet.
• 10:29
  Speaker 3: It's like trying to hear a single pin drop inside
• 10:31
  Speaker 3: a roaring football stadium. You just can't do it with
• 10:34
  Speaker 3: physical mirrors. To measure the low frequency universe, you have
• 10:38
  Speaker 3: to abandon macroscopic mirrors entirely.
• 10:41
  Speaker 2: You can't attach your measurement device to the Earth at all.
• 10:43
  Speaker 3: Now you need test masses that are perfectly identical, completely
• 10:46
  Speaker 3: isolated from thermal noise, and capable of being suspended in
• 10:50
  Speaker 3: a vacuum without physical tethers.
• 10:52
  Speaker 2: Meaning you need individual atoms.
• 10:53
  Speaker 3: This is exactly why the Imperial College team utilizes long
• 10:57
  Speaker 3: baseline atom interferometers.
• 10:59
  Speaker 2: Okay, I want to they the physics of an atom
• 11:01
  Speaker 2: interferometer because this is where the intuitive macroscopic world completely
• 11:04
  Speaker 2: falls apart.
• 11:05
  Speaker 3: It really does.
• 11:06
  Speaker 2: When I think of an interferometer, I picture lego. A
• 11:09
  Speaker 2: laser beam hits a piece of glass, splits in two
• 11:12
  Speaker 2: perpendicular directions, bounces off mirrors, and recombines. The light is
• 11:18
  Speaker 2: the thing being split, right, But in an atom interferometer,
• 11:21
  Speaker 2: you aren't splitting the light. You are splitting the atom itself.
• 11:25
  Speaker 3: We are splitting the atom's quantum wave packet, effectively placing
• 11:29
  Speaker 3: the atom in a spatial superposition, so.
• 11:31
  Speaker 2: It's in two places at once.
• 11:33
  Speaker 3: To understand this, we have to lean heavily on wave
• 11:36
  Speaker 3: particle duality. We tend to visualize atoms as dense little spheres,
• 11:40
  Speaker 3: like microscopic marble.
• 11:42
  Speaker 2: That's how they draw it in high school chemistry.
• 11:44
  Speaker 3: Right, But quantum mechanics dictates that an atom is also
• 11:47
  Speaker 3: a probability wave. Its physical lotation is not a single coordinate.
• 11:51
  Speaker 3: It is a distribution of probabilities.
• 11:53
  Speaker 2: Like the famous double slit experiment. You fire a single
• 11:56
  Speaker 2: particle at a barrier with two slits and it goes
• 11:59
  Speaker 2: through both simultaneously interfering with itself on the other side.
• 12:03
  Speaker 3: Exactly, the atom interferometer is essentially a highly controlled technological
• 12:07
  Speaker 3: application of that exact.
• 12:09
  Speaker 2: Phenomenon, but without physical slits. Right.
• 12:12
  Speaker 3: Instead of physical slits in a barrier, the scientists use
• 12:15
  Speaker 3: pulses of laser light. When a cloud of atoms is
• 12:18
  Speaker 3: dropped in a vacuum chamber, the scientists fire a specifically
• 12:22
  Speaker 3: tuned laser.
• 12:23
  Speaker 2: Pulse at them, a pulse of light.
• 12:26
  Speaker 3: This laser pulse is known as a pie over two pulse.
• 12:29
  Speaker 3: It acts as an optical beam splitter.
• 12:31
  Speaker 2: Okay, let's explore the mechanics of that optical beam splitter.
• 12:34
  Speaker 2: Because a laser carries energy, right, Yes, If you shine
• 12:37
  Speaker 2: a laser at an atom, the atom absorbs a photon,
• 12:40
  Speaker 2: its electron jumps to a higher energy state, and maybe
• 12:44
  Speaker 2: it gets a little physical push from the photon's momentum.
• 12:47
  Speaker 2: How does that put the atom in two places at once?
• 12:49
  Speaker 3: The trick lies in tuning the laser pulse so that
• 12:52
  Speaker 3: there is exactly a fifty percent probability that the atom
• 12:55
  Speaker 3: absorbs the photon and a fifty percent probability.
• 12:58
  Speaker 2: That it does not.
• 12:59
  Speaker 3: Ah, So it's a in quantum mechanics until the system
• 13:02
  Speaker 3: is observed or forced to Decohere, the atom doesn't choose
• 13:06
  Speaker 3: one outcome.
• 13:06
  Speaker 2: It takes both The universe bifurcates the atom state.
• 13:09
  Speaker 3: The wave packet splits. The portion of the wave packet
• 13:12
  Speaker 3: that quote unquote absorbed the photon received a momentum kick.
• 13:16
  Speaker 3: It is physically moving away at a specific velocity. In
• 13:19
  Speaker 3: the other half, the portion of the wave packet that
• 13:21
  Speaker 3: did not absorb the photon remains unaffected. So now a
• 13:25
  Speaker 3: single atom is simultaneously traveling along two diverging physical paths.
• 13:30
  Speaker 2: It is moving and it is staying still. Yes, that
• 13:33
  Speaker 2: is staggering. A physical object, an atom with protons, neutrons,
• 13:39
  Speaker 2: and electrons is occupying two different trajectories in a vacuum
• 13:43
  Speaker 2: chamber simultaneously. So imagine you're holding a laser pointer and
• 13:47
  Speaker 2: you split the beam to hit two identical pendulums. Right,
• 13:50
  Speaker 2: If one pendulum suddenly swings a fraction of a milimeter
• 13:53
  Speaker 2: differently than the other, you know, something invisible just bumped it.
• 13:56
  Speaker 3: That's a great analogy. It travels like that for a
• 13:59
  Speaker 3: set period of life, say a few seconds. The spatial
• 14:01
  Speaker 3: separation between the two paths can reach.
• 14:04
  Speaker 2: Centimeters centimeters, which is astronomical on a quantum scale. Massive.
• 14:09
  Speaker 3: Then the scientists fire a second laser pulse a pipe pulse,
• 14:12
  Speaker 3: which acts like a mirror. It reverses the momentum of
• 14:15
  Speaker 3: the path, so they begin to converge.
• 14:16
  Speaker 2: Back toward each other, bringing it back together.
• 14:18
  Speaker 3: Finally, a third laser pulse acts as a second beam splitter,
• 14:21
  Speaker 3: recombining the two halves of the wave packet, and when.
• 14:24
  Speaker 2: They recombine, they form an interference pattern, just like water
• 14:28
  Speaker 2: waves overlapping in a pond.
• 14:29
  Speaker 3: The resulting interference pattern is exquisitely sensitive to the phase
• 14:33
  Speaker 3: difference between the two paths. The phase is basically the
• 14:36
  Speaker 3: internal timing of the quantum wave. Okay, if the atoms
• 14:39
  Speaker 3: traveled undisturbed in a perfect vacuum, the waves recombine perfectly.
• 14:44
  Speaker 3: But if a gravitational wave passes through the chamber during
• 14:47
  Speaker 3: the flight time, the physical distance of space itself stretches.
• 14:52
  Speaker 2: Space stretches, meaning one of those microscopic paths becomes physically
• 14:56
  Speaker 2: longer than the other.
• 14:57
  Speaker 3: Exactly the path length changes, or, in the case of
• 15:01
  Speaker 3: dark matter, if a dark matter field fluctuates and alters
• 15:04
  Speaker 3: the atom's internal energy state, the phase of the wave.
• 15:07
  Speaker 2: Evolves differently, so they get out of sync.
• 15:09
  Speaker 3: When the two halves recombine, they are slightly out of
• 15:12
  Speaker 3: sync the interference pattern shifts. By measuring the population of
• 15:15
  Speaker 3: atoms in the final state, the scientists can calculate that
• 15:18
  Speaker 3: phase shift with terrifying precision. You now have a sensor
• 15:22
  Speaker 3: that doesn't rely on mirrors physically shaking. The atoms are
• 15:25
  Speaker 3: in free fall. They are immune to the seismic shaking
• 15:28
  Speaker 3: of the vacuum chamber walls because they aren't touching anything.
• 15:31
  Speaker 2: The conceptual elegance of that is undeniable. But this brings
• 15:35
  Speaker 2: us to the theoretical brick wall that has held this
• 15:37
  Speaker 2: entire feel back, which the Imperial team finally had to overcome.
• 15:42
  Speaker 3: Yes, the paradox of the laser.
• 15:44
  Speaker 2: We are using lasers to split, reflect, and recombine these
• 15:47
  Speaker 2: atomic wave packets. The laser is our ruler, but the
• 15:51
  Speaker 2: laser is a physical device and it is subject to
• 15:54
  Speaker 2: its own quantum chaos.
• 15:55
  Speaker 3: We call it laser phase noise, and it is the
• 15:58
  Speaker 3: single greatest adversary in pscon zision metrology.
• 16:01
  Speaker 2: It ruined everything it does.
• 16:03
  Speaker 3: To measure a phase shift in an atom caused by
• 16:05
  Speaker 3: a primordial gravitational wave, you need a ruler that is flawless,
• 16:10
  Speaker 3: but lasers are not perfect continuous waves of light. A
• 16:13
  Speaker 3: laser is generated by pumping energy into a game medium
• 16:16
  Speaker 3: like a crystal or a gas, and stimulating the emission
• 16:18
  Speaker 3: of photons inside an optical cavity.
• 16:21
  Speaker 2: The photons bounce back and forth between mirrors and the
• 16:23
  Speaker 2: laser cavity, stimulating more photons to join them in a
• 16:26
  Speaker 2: coherent beam.
• 16:27
  Speaker 3: Right, But there is a fundamental limit to that coherence,
• 16:31
  Speaker 3: known as the shallow Town's limit. Spontaneous emission photons being
• 16:35
  Speaker 3: emitted randomly by excited atoms in the cavity adds random
• 16:39
  Speaker 3: noise to the optical field.
• 16:40
  Speaker 2: Just random rogue photons exactly.
• 16:43
  Speaker 3: This causes the phase of the laser light to randomly wander.
• 16:47
  Speaker 3: We model it mathematically as a random walk of the
• 16:49
  Speaker 3: optical phase. It stutters. The distance between the crusts and
• 16:53
  Speaker 3: troughs of the light wave jitters microscopically, So.
• 16:56
  Speaker 2: If your ruler's tick marks are physically moving while you
• 16:59
  Speaker 2: are trying to measure something, your measurement is just garbage.
• 17:03
  Speaker 3: For almost any application on Earth, telecommunications, atomic clocks, light
• 17:07
  Speaker 3: bar this phase noise can be suppressed enough to not matter.
• 17:10
  Speaker 2: Right, you lock it to something stable.
• 17:12
  Speaker 3: You lock the laser to an ultra stable optical cavity
• 17:15
  Speaker 3: which acts as a physical reference. But even the best
• 17:18
  Speaker 3: cavity stabilized clock lasers in the world have inherent thermal
• 17:21
  Speaker 3: noise in their mirrors. The residual phase noise of the
• 17:24
  Speaker 3: laser is orders of magnitude larger than the phase shift
• 17:27
  Speaker 3: you are trying to measure from a dark matter wave.
• 17:30
  Speaker 2: Let me visualize this math for a second. Think of
• 17:32
  Speaker 2: the internal phase of the atomic wave packet. Like two
• 17:35
  Speaker 2: runners on a track. The laser is the stopwatch timing them.
• 17:39
  Speaker 2: I like that, but the phase noise means the stopwatch
• 17:42
  Speaker 2: is randomly jumping forward and backward by milliseconds. You want
• 17:46
  Speaker 2: to measure if one runner finishes a billionth of a
• 17:49
  Speaker 2: second faster than the other, But your stopwatch is wildly hallucinating.
• 17:54
  Speaker 3: It's completely blinding the sensor.
• 17:56
  Speaker 2: The noise completely buries the data. It's like turning on
• 17:58
  Speaker 2: a massive spotlight to find firefly, but the spotlight is
• 18:01
  Speaker 2: so blindingly bright that it washes out the firefly entirely.
• 18:06
  Speaker 2: How do we keep the light but lose the glare?
• 18:08
  Speaker 3: Well, you cannot extract the signal from a single atom interferometer.
• 18:12
  Speaker 3: If you look at the readoubt the phase shift caused
• 18:15
  Speaker 3: by the laser noise is entirely indistinguishable from the phase
• 18:18
  Speaker 3: shift caused by a gravitational wave.
• 18:20
  Speaker 2: You can't tell them apart.
• 18:21
  Speaker 3: The mathematical solution to this problem was proposed years ago,
• 18:25
  Speaker 3: which is differential measurement using a single laser to drive
• 18:28
  Speaker 3: multiple interferometers simultaneously.
• 18:31
  Speaker 2: Let's expand on the track analogy. If the stopwatch is broken,
• 18:34
  Speaker 2: you don't time the runners against the clock. You measure
• 18:36
  Speaker 2: the runners against each other exactly. You put two pairs
• 18:39
  Speaker 2: of runners on the track. The stopwatch might be hallucinating,
• 18:42
  Speaker 2: but it hallucinates for all four runners simultaneously.
• 18:45
  Speaker 3: The architecture is known as a long baseline gradiometer. You
• 18:49
  Speaker 3: place two separate clouds of atoms inside the same long
• 18:53
  Speaker 3: vacuum tube, separated by a large distance. You use one
• 18:58
  Speaker 3: single laser beam traverse the length of the tube to
• 19:01
  Speaker 3: pulse both clouds simultaneously, one being for both. Because the
• 19:05
  Speaker 3: speed of light is so incredibly fast, the laser pulse
• 19:07
  Speaker 3: hits Cloud A and Cloud B at almost the exact
• 19:10
  Speaker 3: same instant.
• 19:11
  Speaker 2: So the phase error the jitter is imprinted onto both
• 19:14
  Speaker 2: clouds identically. It is common mode noise.
• 19:17
  Speaker 3: In a theoretical vacuum. If you subtract the phase readout
• 19:20
  Speaker 3: of cloud A from cloud B, the common laser noise
• 19:23
  Speaker 3: mathematically cancels itself out to zero. The local oscillator noise vanishes,
• 19:28
  Speaker 3: oof gone. What remains is only the differential phase shift,
• 19:31
  Speaker 3: the tiny difference caused by something physically altering the space
• 19:34
  Speaker 3: between the two clouds.
• 19:36
  Speaker 2: That's the theoretical whiteboard math. But the physics community demanded
• 19:40
  Speaker 2: empirical proof. Proving that common mode rejection works at the
• 19:44
  Speaker 2: quantum limit inside a physical machine surrounded by real world
• 19:48
  Speaker 2: electromagnetic fields, vacuum imperfections, and thermal gradients is an entirely
• 19:53
  Speaker 2: different beast.
• 19:54
  Speaker 3: It really is.
• 19:55
  Speaker 2: This takes us directly into the Imperial Ultra Coold Strontium
• 19:58
  Speaker 2: Laboratory prove this theory. They didn't just build the machine.
• 20:03
  Speaker 2: They subjected it to a torture test.
• 20:05
  Speaker 3: They absolutely did.
• 20:06
  Speaker 2: But before we get to the torture, we have to
• 20:08
  Speaker 2: talk about the medium they chose. Because they didn't use
• 20:11
  Speaker 2: hydrogen or helium, they use strontium eighty seven.
• 20:13
  Speaker 3: Strontium eighty seven is arguably the most critical element in
• 20:17
  Speaker 3: modern precision physics. It is an alkaline earth metal and
• 20:21
  Speaker 3: Its specific atomic structure is what makes it so valuable.
• 20:24
  Speaker 2: Let's drill into that structure. Why is strontium better than say, rubidium,
• 20:28
  Speaker 2: which is used in a lot of standard atomic clocks.
• 20:30
  Speaker 3: It comes down to the arrangement of its electrons. Strontium
• 20:33
  Speaker 3: is in group two of the periodic table, meaning it
• 20:36
  Speaker 3: has two valence electrons in its outermost shell. The interaction
• 20:39
  Speaker 3: between these two electrons creates a very specific set of
• 20:42
  Speaker 3: energy states.
• 20:43
  Speaker 2: Okay, In quant mechanics, electrons have a property called spin.
• 20:48
  Speaker 2: The two valence electrons can have opposite spins, a state
• 20:51
  Speaker 2: we call a singlet, or they can have parallel spins,
• 20:54
  Speaker 2: a state we call a triplet.
• 20:56
  Speaker 3: And jumping between those states is what allows us to
• 20:59
  Speaker 3: use it as a clock or a sensor exactly.
• 21:01
  Speaker 2: The transition from the lowest energy singlet state to the
• 21:04
  Speaker 2: lowest energy triplet state is severely restricted by the quantum
• 21:07
  Speaker 2: selection rules. It is what physicists call a doubly forbidden transition.
• 21:12
  Speaker 2: Doubly forbidden under normal circumstances, an electron doesn't want to
• 21:16
  Speaker 2: make that jump. This means the excited state is incredibly
• 21:20
  Speaker 2: long lived. If you manage to excite the electron into
• 21:23
  Speaker 2: that triplet state. It will stay there for hundreds of
• 21:26
  Speaker 2: seconds before decaying back down.
• 21:28
  Speaker 3: One hundreds of seconds. Lifetime is an absolute eternity in
• 21:31
  Speaker 3: atomic physics. Most things decay in microseconds, right, and.
• 21:35
  Speaker 2: An incredibly long lifetime translates directly into an incredibly narrow
• 21:39
  Speaker 2: resonance lined with the energy required to trigger that jump
• 21:43
  Speaker 2: is hyper specific. It operates at an optical frequency hundreds.
• 21:47
  Speaker 3: Of terror herts, so it's super precise that sharp resonance
• 21:50
  Speaker 3: is the tick of an optical atomic clock. Furthermore, because
• 21:54
  Speaker 3: of its specific nuclear spin, the strontium eighty seven atom
• 21:58
  Speaker 3: can be placed in a state where it is highly
• 21:59
  Speaker 3: in sensitive to stray magnetic fields or ambient temperature fluctuations.
• 22:04
  Speaker 2: It is a pendulum that refuses to be disturbed by
• 22:06
  Speaker 2: the environment exactly, But the strontium has to be completely
• 22:09
  Speaker 2: still for this to work, which means they have to
• 22:11
  Speaker 2: freeze it. And when physicists say ultra coold, they aren't
• 22:15
  Speaker 2: talking about liquid nitrogen.
• 22:17
  Speaker 3: No much colder.
• 22:18
  Speaker 2: They are talking about temperatures fractions of a degree above
• 22:22
  Speaker 2: absolute zero. Now I have to point out the contradiction here.
• 22:25
  Speaker 2: You mentioned the use lasers to cool the atoms, but
• 22:28
  Speaker 2: lasers are concentrated beams of energy. We use lasers to
• 22:32
  Speaker 2: cut steel and weld metal we do how does shooting
• 22:35
  Speaker 2: a high energy laser beam at an atom freeze it.
• 22:37
  Speaker 3: It is one of the most brilliant applications of fundamental
• 22:40
  Speaker 3: physics laser cooling, specifically Doppler cooling. We have to reconsider
• 22:44
  Speaker 3: what temperature actually is. Temperature is just macroscopic kinetic energy.
• 22:48
  Speaker 3: A hot gas is just a swarm of atoms moving
• 22:51
  Speaker 3: very fast. A cold gas is atoms moving slowly. Makes
• 22:54
  Speaker 3: sense if a cloud of strontium gas is at room temperature,
• 22:58
  Speaker 3: the individual atoms are zipping around at hundreds of meters
• 23:01
  Speaker 3: per second.
• 23:02
  Speaker 2: If they are moving that fast, they would smash into
• 23:04
  Speaker 2: the walls of the vacuum chamber before you could even
• 23:06
  Speaker 2: fire the beam.
• 23:07
  Speaker 3: Splitter pulses exactly to slow them down. Scientists exploit the
• 23:12
  Speaker 3: Doppler effect and the conservation of momentum. A photon of
• 23:16
  Speaker 3: laser light has no mass, but it does carry momentum.
• 23:20
  Speaker 3: When an atom absorbs a photon, it absorbs that momentum
• 23:24
  Speaker 3: and receives a physical kick in the direction the photon
• 23:27
  Speaker 3: was traveling.
• 23:28
  Speaker 2: Like getting hit by a tiny bowling ball.
• 23:30
  Speaker 3: Now, if you tune the laser perfectly to the atom's
• 23:33
  Speaker 3: resonant frequency, the atom absorbs it, but the researchers deliberately
• 23:37
  Speaker 3: detune the laser. They make the laser frequency slightly lower,
• 23:41
  Speaker 3: slightly red shifted than the atom's resonance.
• 23:44
  Speaker 2: So if the atom is just sitting still, the laser
• 23:46
  Speaker 2: light is the wrong color, the atom ignores it.
• 23:48
  Speaker 3: The atom is completely transparent to the red shifted light. However,
• 23:52
  Speaker 3: if the atom is physically moving toward the laser beam,
• 23:55
  Speaker 3: the Doppler effect comes into play. Just like a police
• 23:57
  Speaker 3: siren sounds higher pitched as the car speeds toward you,
• 24:01
  Speaker 3: the light wave appears blue shifted from the perspective of
• 24:03
  Speaker 3: the moving atom.
• 24:05
  Speaker 2: The atom's own forward velocity shifts the light up into resonance.
• 24:09
  Speaker 3: The atom suddenly sees the exact right color of light.
• 24:12
  Speaker 3: It absorbs the photon. The photon was traveling in the
• 24:16
  Speaker 3: opposite direction, so it's a momentum acts like a microscopic
• 24:19
  Speaker 3: brake pedal. The atom slows down.
• 24:22
  Speaker 2: Slightly, that is genius.
• 24:24
  Speaker 3: The atom then spontaneously emits a photon in a random direction,
• 24:28
  Speaker 3: losing that extra energy, and is ready to absorb another
• 24:31
  Speaker 3: one by setting up six. Intercepting laser beams from all directions,
• 24:36
  Speaker 3: you create an optical molasses.
• 24:38
  Speaker 2: Optical molasses.
• 24:39
  Speaker 3: No matter which way an atom tries to move, it
• 24:42
  Speaker 3: moves into a red shifted laser beam, blue shifts it
• 24:45
  Speaker 3: into resonance, absorbs the momentum, and slows down.
• 24:48
  Speaker 2: Sort of like trying to run through a room while
• 24:50
  Speaker 2: thousands of people are throwing ping pong balls at you
• 24:52
  Speaker 2: from every direction, but they only hit you if you
• 24:54
  Speaker 2: run toward them.
• 24:55
  Speaker 3: That's a perfect image. Over thousands of cycles, the atoms
• 24:58
  Speaker 3: lose all their kinetic energy and freeze in place, reaching
• 25:01
  Speaker 3: temperatures of a few microkelvin. They gather these frozen strontium
• 25:05
  Speaker 3: eighty seven atoms in a magneto optical trap. The Imperial
• 25:09
  Speaker 3: team created two distinct clouds of these ultra coold atoms,
• 25:13
  Speaker 3: separated by a physical distance within their apparatus. They linked
• 25:17
  Speaker 3: them with a single ultrastable clock laser.
• 25:20
  Speaker 2: Okay, so the setup is complete.
• 25:22
  Speaker 3: The goal was to fire the laser, split the wave
• 25:25
  Speaker 3: packets of both clouds, recombine them, and measure the differential
• 25:29
  Speaker 3: phase shift. But as we discussed, they didn't just run
• 25:32
  Speaker 3: the experiment in ideal conditions. They set out to prove
• 25:35
  Speaker 3: common mode noise cancelation in a worst possible.
• 25:38
  Speaker 2: Environment, the torture test. Here's where it gets really interesting.
• 25:42
  Speaker 2: Instead of trying to build a perfectly quiet room, they
• 25:45
  Speaker 2: intentionally brought in a brass band just to prove they
• 25:47
  Speaker 2: could tune it out. They deliberately sabotage their own ultra
• 25:50
  Speaker 2: stable laser.
• 25:51
  Speaker 3: What's fascinating here is they injected vast amounts of artificial
• 25:54
  Speaker 3: white noise into the laser's frequency stabilization circuit. They forced
• 25:59
  Speaker 3: the phase of the laser to jitter.
• 26:00
  Speaker 2: Violently, just shaking the rulers hard as they could.
• 26:03
  Speaker 3: They essentially simulated the conditions of a massive kilometer scale
• 26:07
  Speaker 3: detector operating in a highly unstable environment. They wanted the
• 26:12
  Speaker 3: noise to be so severe that it entirely overwhelmed the
• 26:15
  Speaker 3: atomic resonance.
• 26:16
  Speaker 2: So when they ran the experiment with this artificially noisy laser,
• 26:21
  Speaker 2: what did the raw data look like? If I just
• 26:23
  Speaker 2: looked at the readout for cloud A, what am I seeing?
• 26:26
  Speaker 3: Total static?
• 26:27
  Speaker 2: Total static?
• 26:28
  Speaker 3: The final readout of an atom interferometer is a transition probability,
• 26:32
  Speaker 3: a ratio of how many atoms ended up in the
• 26:34
  Speaker 3: excited state. Versus the ground state. If the laser is stable,
• 26:38
  Speaker 3: you can map that probability to a precise phase angle.
• 26:42
  Speaker 3: But with the injected noise, the phase of the laser
• 26:45
  Speaker 3: was jumping wildly during the flight time.
• 26:47
  Speaker 2: Of the atoms, so the fringes were gone.
• 26:48
  Speaker 3: The interference fringes were entirely washed out. The readout for
• 26:52
  Speaker 3: Cloud A looked like a completely random scatterplot.
• 26:54
  Speaker 2: And Cloud B is the exact same, a random scatter
• 26:57
  Speaker 2: of garbage.
• 26:58
  Speaker 3: Data, completely unintelligible on its own. The phase noise was
• 27:02
  Speaker 3: orders of magnitude larger than any physical signal they could
• 27:04
  Speaker 3: hope to measure. But then came the crucial step, which
• 27:07
  Speaker 3: is the differential data analysis. The phase of the laser,
• 27:11
  Speaker 3: let's call it FI of T was wild and random,
• 27:14
  Speaker 3: but because the speed of light is constant, the laser
• 27:18
  Speaker 3: beam delivered that exact same random pi of T to
• 27:20
  Speaker 3: Cloud A and Cloud B simultaneously.
• 27:23
  Speaker 2: The track stretch for all the runners at the exact
• 27:25
  Speaker 2: same time.
• 27:26
  Speaker 3: When the team plotted the transition probability of Cloud A
• 27:30
  Speaker 3: against the transition probability of Cloud B on a two
• 27:33
  Speaker 3: dimensional graph, the chaos collapsed into order.
• 27:36
  Speaker 2: Wow.
• 27:37
  Speaker 3: The random scatter points formed a perfect lisagious.
• 27:40
  Speaker 2: Ellipse melicitious ellipse.
• 27:42
  Speaker 3: The geometry of that ellipse allowed them to extract the
• 27:45
  Speaker 3: exact phase difference between the two clouds by mathematically subtracting
• 27:49
  Speaker 3: the phase of A from B the term fi of T.
• 27:52
  Speaker 3: The laser noise was completely nullified.
• 27:54
  Speaker 2: It evaporated. It's exactly like high end active noise canceling headphones.
• 27:58
  Speaker 2: The headphones record the enng roar of the airplane, create
• 28:01
  Speaker 2: an exact opposite sound wave, and play it into your
• 28:04
  Speaker 2: ear so you only hear your music. They did this,
• 28:07
  Speaker 2: but with quantum atomic states.
• 28:08
  Speaker 3: They did the shared noise disappeared, leaving only the deterministic
• 28:12
  Speaker 3: difference between the two physical locations. The measurement precision dropped
• 28:16
  Speaker 3: right down to the fundamental quantum projection noise limit. They
• 28:20
  Speaker 3: recovered the theoretical ideal inside a violently noisy reality.
• 28:25
  Speaker 2: To absolutely nail this down, they took it one step further.
• 28:28
  Speaker 2: Because it's not enough to just cancel the noise, right,
• 28:31
  Speaker 2: you have to prove you didn't accidentally cancel the actual
• 28:35
  Speaker 2: cosmic signal you're looking for.
• 28:36
  Speaker 3: Yes, that's a huge concern.
• 28:38
  Speaker 2: They needed a fake gravitational wave, a fake dark matter interaction.
• 28:43
  Speaker 2: How do you simulate the warping of space time in
• 28:45
  Speaker 2: a laboratory in London.
• 28:47
  Speaker 3: You introduce a differential phase shift that is entirely independent
• 28:50
  Speaker 3: of the laser noise. The researchers did this by physically
• 28:53
  Speaker 3: modulating the laser beam delivery path. They induced an oscillating
• 28:57
  Speaker 3: phase shift at a specific frequency.
• 29:00
  Speaker 2: Let's call it a synthetic cosmic signal.
• 29:02
  Speaker 3: This synthetic signal was buried deep beneath the artificial laser noise.
• 29:06
  Speaker 2: So they threw a microscopic rhythmic signal into a sea
• 29:09
  Speaker 2: of raging static.
• 29:10
  Speaker 3: When they analyzed Cloud A alone, the synthetic signal was
• 29:14
  Speaker 3: entirely invisible. When they analyzed Cloud B alone, it was invisible.
• 29:19
  Speaker 3: But the moment they performed the differential subtraction, canceling the
• 29:23
  Speaker 3: common mode laser noise, the synthetic signal emerged perfectly intact.
• 29:28
  Speaker 2: That is just phenomenal.
• 29:29
  Speaker 3: Oscillating rhythm was stark and clear in the differential data.
• 29:33
  Speaker 3: The sensor was blinded by its own tool, and yet
• 29:36
  Speaker 3: it still saw the target.
• 29:38
  Speaker 2: It is the ultimate validation of the gradiometer architecture. Doctor
• 29:43
  Speaker 2: Charles Baynham, who co leads the ultra cold Strontium Laboratory
• 29:47
  Speaker 2: noted something profound about this. He said that physicists have
• 29:50
  Speaker 2: known for a long time that quantum sensors can help
• 29:53
  Speaker 2: us understand the universe, but it's only recently that has
• 29:56
  Speaker 2: become possible to build them with the resolution needed.
• 29:58
  Speaker 3: He's absolutely right.
• 29:59
  Speaker 2: A I can't wait for the day when signals from
• 30:02
  Speaker 2: an atom are telling us about a black hole that
• 30:04
  Speaker 2: merged millions of years ago. We don't have to be
• 30:06
  Speaker 2: paralyzed by the imperfections of our lasers anymore. We can
• 30:09
  Speaker 2: mathematically strip them away.
• 30:10
  Speaker 3: The implications of this are difficult to overstate. This single
• 30:14
  Speaker 3: experiment bridges the gap between theoretical quantum metrology and large
• 30:19
  Speaker 3: scale operational observatories. A tabletop experiment in a London basement
• 30:24
  Speaker 3: is literally the architectural blueprint for the largest physics installations
• 30:28
  Speaker 3: of the next century, and.
• 30:29
  Speaker 2: This scales up rapidly because the further apart you place
• 30:32
  Speaker 2: the two clouds of atoms, the more sensitive the detector
• 30:35
  Speaker 2: becomes to the stretching of space time soonentially, so if
• 30:38
  Speaker 2: a wave stretches space by a fraction of an atom
• 30:41
  Speaker 2: over one meter, it stretches space by one hundred atoms
• 30:44
  Speaker 2: over one hundred meters. This brings us to the global
• 30:47
  Speaker 2: initiative heavily referenced in the wake of this breakthrough, the
• 30:50
  Speaker 2: AION Collaboration.
• 30:52
  Speaker 3: AION stands for the Atom Interferometer, Observatory and Network. It
• 30:56
  Speaker 3: is a major UK initiative heavily funded by the Quantum
• 31:00
  Speaker 3: Technologies for Fundamental Physics program. Okay, the Imperial College breakthrough
• 31:04
  Speaker 3: is a cornerstone of aion n's roadmap. The immediate next
• 31:07
  Speaker 3: step is taking this tabletop technology and standing it up vertically.
• 31:11
  Speaker 3: They're constructing a ten meter atom interferometer.
• 31:14
  Speaker 2: Instead of firing the atoms horizontally, you drop them in
• 31:17
  Speaker 2: a vertical vacuum tube.
• 31:18
  Speaker 3: You utilize Earth's gravity to increase the flight time. You
• 31:22
  Speaker 3: launch the ultra coold strontium atoms upward inside a ten
• 31:25
  Speaker 3: meters vacuum shaft, apply the laser pulses as they rise
• 31:29
  Speaker 3: and fall in a ballistic trajectory, and read the interference
• 31:32
  Speaker 3: pattern at the bottom.
• 31:33
  Speaker 2: Like throwing a ball in the air exactly.
• 31:36
  Speaker 3: A longer flight time means the atoms are in superposition longer,
• 31:39
  Speaker 3: which means they accumulate a larger phase shift from any
• 31:42
  Speaker 3: passing gravitational wave or dark matter field.
• 31:45
  Speaker 2: But ten meters is just the stepping stone aion is
• 31:48
  Speaker 2: tied into a massive global effort. There is the MEAGS
• 31:51
  Speaker 2: project at Ferma Lab in the United States, which is
• 31:54
  Speaker 2: building a one hundred meter vertical shaft atom interferometer.
• 31:58
  Speaker 3: Well one hundred meters.
• 31:59
  Speaker 2: One hundred meters your vacuum chamber filled with absolute silence,
• 32:02
  Speaker 2: magnetic shielding, and clouds of frozen atoms.
• 32:06
  Speaker 3: MAGI is currently under construction in the Minos Access shaft
• 32:09
  Speaker 3: at Fermilab. The engineering challenges are formidable. You have to
• 32:13
  Speaker 3: maintain an ultra high vacuum over one hundred meters volume.
• 32:15
  Speaker 2: That's tough.
• 32:16
  Speaker 3: You have to shield the entire shaft from ambient magnetic
• 32:19
  Speaker 3: fields because even a slight fluctuation in earth magnetic field
• 32:23
  Speaker 3: can cause a phase shift in the atoms via the
• 32:26
  Speaker 3: Zeeman effect. And you have to deliver a perfectly collimated
• 32:29
  Speaker 3: laser beam over that entire distance without it diverging or
• 32:33
  Speaker 3: picking up acoustic vibrations from the mirrors, which.
• 32:36
  Speaker 2: Is exactly why the Imperial College noise cancelation breakthrough is mandatory.
• 32:41
  Speaker 2: Over one hundred meters, the laser phase noise would be catastrophic.
• 32:45
  Speaker 2: The differential measurement is the only way Magis produces usable science.
• 32:48
  Speaker 3: It's the key to the whole project.
• 32:50
  Speaker 2: But the endgame for this technology is even more ambitious.
• 32:54
  Speaker 2: It involves pivoting one of the most famous scientific institutions
• 32:57
  Speaker 2: on Earth. We are talking about CERN, the.
• 33:00
  Speaker 3: Proposed ACE project, the Atom Interferometry CERN experiment. If realized,
• 33:05
  Speaker 3: this would place a kilometer scale atom interferometer in the
• 33:08
  Speaker 3: underground infrastructure at CERN in Switzerland.
• 33:11
  Speaker 2: So what does this all mean for the future. Are
• 33:13
  Speaker 2: we going to see underground tunnels stretching for miles, not
• 33:16
  Speaker 2: filled with smashing particles, but with clouds of perfectly still
• 33:20
  Speaker 2: freezing cold atoms. Because CERN is synonymous with particle colliders,
• 33:25
  Speaker 2: the Large Hadrin collider smashing protons together at near the
• 33:29
  Speaker 2: speed of light in a twenty seven kilometer ring to
• 33:32
  Speaker 2: tear them apart and find the Higgs boson, it is
• 33:35
  Speaker 2: the cathedral of high energy physics.
• 33:37
  Speaker 3: And that represents a massive, necessary paradigm shift in fundamental physics.
• 33:42
  Speaker 3: For seventy years, the frontier physics has been high energy.
• 33:45
  Speaker 3: To probe smaller and smaller distances, you need shorter and
• 33:48
  Speaker 3: shorter wavelengths of probing particles, which requires higher and higher
• 33:52
  Speaker 3: collision energies.
• 33:53
  Speaker 2: It is brute force physics. Build a bigger ring, smash
• 33:56
  Speaker 2: them harder.
• 33:56
  Speaker 3: But we are approaching the practical and financial limits of
• 33:59
  Speaker 3: the collider Pairsaradei'm to find the next layer of physics.
• 34:02
  Speaker 3: Supersymmetry or whatever lies beyond the standard model might require
• 34:06
  Speaker 3: a collider the size.
• 34:07
  Speaker 2: Of the Solar System. We obviously can't build that. We can't.
• 34:10
  Speaker 3: So physics is turning from high energy to high precision.
• 34:13
  Speaker 3: Is represents a transition from brute force to ultimate subtlety.
• 34:18
  Speaker 3: Instead of smashing particles to see what falls out, we
• 34:21
  Speaker 3: freeze particles to near absolute zero, put them in a
• 34:24
  Speaker 3: pristine quantum state, and just wait for the subtle ambient
• 34:28
  Speaker 3: physics of the universe to alter them.
• 34:30
  Speaker 2: It is the difference between blowing up a mountain to
• 34:32
  Speaker 2: study the rocks and building a flawless seismograph to listen
• 34:36
  Speaker 2: to the continental plate shift. Beautifully, said, A kilometer scale
• 34:40
  Speaker 2: atom interferometer at CERN would be insulated from surface noise
• 34:44
  Speaker 2: by hundreds of meters of solid rock. It would be
• 34:47
  Speaker 2: a sensor of unimaginable sensitivity.
• 34:49
  Speaker 3: A facility of that scale would operate in the midband
• 34:51
  Speaker 3: frequency of gravitational waves between one to one and ten hertz.
• 34:55
  Speaker 3: This is the critical gat between LEGO and the space
• 34:58
  Speaker 3: based LYSA.
• 34:59
  Speaker 2: Observatory, the missing puzzle piece.
• 35:01
  Speaker 3: It is the frequency band where intermediate mass black holes merge.
• 35:05
  Speaker 3: It is the frequency where we might detect the stochastic
• 35:07
  Speaker 3: background of the Big Bang itself, and it is highly
• 35:09
  Speaker 3: sensitive to the exact frequencies where ultra light dark matter
• 35:12
  Speaker 3: fields are theorized to oscillate.
• 35:14
  Speaker 2: Doctor Richard Hobson, another researcher on the Imperial team, framed
• 35:17
  Speaker 2: this beautifully. He pointed out that we have taken the
• 35:20
  Speaker 2: most exquisite precise instruments ever devised by human engineering, atomic
• 35:25
  Speaker 2: clocks and interferometers, and we are entirely repurposing them.
• 35:29
  Speaker 3: It's true.
• 35:29
  Speaker 2: They aren't just for keeping atomic time for GPS satellites anymore.
• 35:32
  Speaker 2: They are telescopes. We are using the internal mechanics of
• 35:36
  Speaker 2: a watch to map the invisible architecture of the cosmos.
• 35:39
  Speaker 3: Professor Oliver Buckmueller, who has been instrumental in bridging the
• 35:43
  Speaker 3: gap between quantum technologies and high energy physics, called this
• 35:47
  Speaker 3: experiment a definitive milestone for both magis.
• 35:51
  Speaker 2: And ae the proof of concept.
• 35:53
  Speaker 3: The theoretical architecture has been dalidated, the noise can be managed.
• 35:57
  Speaker 3: The roadmap to kilometer scale quantum sences is no longer
• 36:01
  Speaker 3: blocked by the paradox of the laser.
• 36:03
  Speaker 2: The path is clear. We just have to build the
• 36:05
  Speaker 2: massive underground shafts and deploy the strontium clouds.
• 36:08
  Speaker 3: When those large scale interferometers power on and the differential
• 36:12
  Speaker 3: subtraction is applied, we will be peering into an entirely
• 36:16
  Speaker 3: new spectrum of reality. We may finally chart the dark
• 36:20
  Speaker 3: matter wind that is blowing through our Solar system as
• 36:23
  Speaker 3: we orbit the galactic center the dark matter wind, we
• 36:26
  Speaker 3: may decode the gravitational echoes of the universe's first expansion.
• 36:30
  Speaker 2: We have spent an hour diving deep into the absolute
• 36:34
  Speaker 2: limits of human perception. We've traced the physics from the
• 36:37
  Speaker 2: rotational curves of distant galaxies, down to the singlet triplet
• 36:41
  Speaker 2: energy states of an alkaline earth metal and back out
• 36:45
  Speaker 2: to the primordial expansion of space itself.
• 36:47
  Speaker 3: It's a vast journey.
• 36:48
  Speaker 2: We are standing at the threshold of a new era
• 36:51
  Speaker 2: of astronomy. For millennia, astronomy has been about looking, looking
• 36:55
  Speaker 2: with the naked eye, looking with ground based glass lenses,
• 36:58
  Speaker 2: looking with orbital mirrors and radio. We have relied on
• 37:01
  Speaker 2: the electromagnetic spectrum light to tell us what the universe is.
• 37:04
  Speaker 2: But the majority of the universe doesn't speak in light.
• 37:07
  Speaker 3: It speaks in gravity, and it speaks in mass. And
• 37:09
  Speaker 3: to listen to that language we cannot use lenses. We
• 37:12
  Speaker 3: must transition from looking to feeling.
• 37:15
  Speaker 2: From looking to feeling.
• 37:16
  Speaker 3: We are leveraging the fundamental building blocks of matter, forcing
• 37:20
  Speaker 3: them into a state of quantum superposition and allowing the
• 37:23
  Speaker 3: cosmos to physically interact with them. We are using atoms
• 37:26
  Speaker 3: as raw nerve endings for the human species.
• 37:29
  Speaker 2: Using atoms as nerve endings. It is a profound shift
• 37:32
  Speaker 2: in our relationship with nature, and it begs an even larger,
• 37:36
  Speaker 2: almost philosophical reflection on the limits of our own biological sensors.
• 37:40
  Speaker 2: We walk through a world that feels solid, empty, and silent,
• 37:45
  Speaker 2: but the Imperial College experiment proves that the silence is
• 37:48
  Speaker 2: an illusion created by our inability to process the data.
• 37:51
  Speaker 3: Our macroscopic sensory apparatus site hearing touch is an evolutionary
• 37:56
  Speaker 3: adaptation designed for survival on a specific rocky planet, not
• 38:00
  Speaker 3: for interpreting the fundamental structure of the cosmos. The static
• 38:03
  Speaker 3: of everyday life blinds us to the underlying reality.
• 38:05
  Speaker 2: The phase noise of being human. Exactly, the mathematics of
• 38:08
  Speaker 2: differential measurement allows us to strip away the overwhelming quantum
• 38:12
  Speaker 2: static of our lasers to reveal the invisible forces of
• 38:15
  Speaker 2: dark matter and ancient black holes. It makes you wonder
• 38:18
  Speaker 2: what else is hiding in plain sight.
• 38:20
  Speaker 3: It really does.
• 38:20
  Speaker 2: If we could put on quantum noise canceling headphones for
• 38:24
  Speaker 2: our own human perception, what would we feel. We would
• 38:27
  Speaker 2: realize we are walking through a blizzard of dark matter.
• 38:30
  Speaker 2: We are being gently squeezed by the dying breaths of
• 38:33
  Speaker 2: black holes. The Leviathans are in the room with us,
• 38:37
  Speaker 2: breathing against our skin every second of the day. We
• 38:40
  Speaker 2: just had to invent the math to tune out our
• 38:42
  Speaker 2: own noise so we could finally feel them.
• 38:44
  Speaker 3: It is a humbling realization. The universe is not an
• 38:47
  Speaker 3: empty stage. It is a densely woven, vibrating tapestry, and
• 38:52
  Speaker 3: we are inextricably woven into it.
• 38:54
  Speaker 2: That is a staggering thought to carry with you today.
• 38:56
  Speaker 2: The universe is ringing, and we are finally learning how
• 38:58
  Speaker 2: to listen, keep wondering, keep pushing the boundaries of what
• 39:01
  Speaker 2: you think is real, and stay curious until next time.