[HN Gopher] Physicists create elusive particles that remember th...
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Physicists create elusive particles that remember their pasts
Author : peter_d_sherman
Score : 90 points
Date : 2023-09-12 12:46 UTC (10 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| gus_massa wrote:
| Note that they don't remember all their past (like a gps device
| with a memory). They just remember how many times one of them has
| looped around a second one. This is well defined because they
| live in a plane. More details in
| https://en.wikipedia.org/wiki/Anyon
| criddell wrote:
| Is there only one past? Is _the number of times_ represented as
| a discrete value or a function with some distribution? Is the
| time component one way, or could it make sense to remember how
| many times it will loop in the future?
| jkercher wrote:
| Cool. Let us software guys know when we get computers that are
| 1000x faster so we can write the next language/framework that is
| 1000x slower.
| bondarchuk wrote:
| So did they create particles or just simulate the creation of
| particles on a quantum computer?
|
| > _Some physicists consider these efforts simulations, because
| the qubits inside the processor are abstractions of particles
| (while their physical nature varies from lab to lab, you can
| visualize them as particles spinning around an axis). But the
| quantum nature of the qubits is real, so -- simulations or not --
| the processors have become playgrounds for topological
| experiments._
|
| So far (AFAIU) anything that can be simulated on a qc can also be
| simulated (much more easily) on a classical computer. Did the
| simulation leverage specific quantum properties of the qubits in
| a way that resulted in a genuinely never-seen-before physical
| system, or did they just simulate it on a qc for the heck of it?
|
| Guess I'll wait for the Scott Aaronson writeup.
|
| Edit: feeling kinda bad to give the stereotypical
| skeptical/dismissive comment, so I want to stress that I
| legitimately don't understand a lot of what is actually happening
| here. Maybe it's way cooler than I'm making it out to be.
| [deleted]
| m-watson wrote:
| This Quanta piece is from May and is talking about work that
| came out in October 2022 so if Aaronson was going to write a
| piece he probably already did (maybe, obviously my assumptions
| could be completely wrong).
|
| But the abstract of the pre-print
| (https://arxiv.org/abs/2210.10255) covers some of what you are
| asking:
|
| "Despite the well developed mathematical description of non-
| Abelian anyons and numerous theoretical proposals, the
| experimental observation of their exchange statistics has
| remained elusive for decades. Controllable many-body quantum
| states generated on quantum processors offer another path for
| exploring these fundamental phenomena. While efforts on
| conventional solid-state platforms typically involve
| Hamiltonian dynamics of quasi-particles, superconducting
| quantum processors allow for directly manipulating the many-
| body wavefunction via unitary gates."
|
| They created a collection of quasi-particles that has different
| statistical properties that we don't see in 3D (the Non-abelian
| anyon https://en.wikipedia.org/wiki/Anyon). So simulated or
| created becomes a tricky word here, the quantum processor is
| putting these qubits into a state that acts as a quasi-particle
| so they can study it directly. So no a classical computer would
| not be able to do this in the same way it would have to use
| classical bits to simulate the quasi-particle.
| divs1210 wrote:
| Thanks for the explanation.
|
| That quote is extremely terse and would have taken a
| considerable amount of time to understand.
| nuancebydefault wrote:
| I believe the blue figure in the middle of the article
| shows such a 'simulation'. It is called a simulation
| because quasi particles (ie groups of physical particles)
| are treated as qbits.
| dexwiz wrote:
| From what I understand most qubits are implemented as trapped
| ions or quantum dots which are both collections of particles
| instead of a single particle. For quantum dots you may have
| thousands or millions of atoms in a single dot, since they are
| nano crystals. Their behavior is quantum so they can be called
| "particles," but not in the same way an electron or quark are
| fundamental particles.
|
| The simulation is like a reverse of those scaled flood models.
| Yes it's a scaled simulation, but the same fluid dynamics come
| into play. It's not a math model simulation like you would
| perform on a classical computer.
| nathan_compton wrote:
| >So far (AFAIU) anything that can be simulated on a qc can also
| be simulated (much more easily) on a classical computer.
|
| A few things about this idea.
|
| 1. It really depends on what you mean by "more easily." From a
| technical perspective, yes, simulating this on a classical
| computer is much easier. But simulating this on a quantum
| computer gives an exponential speed up, presuming you can live
| with the provisos associated with such a simulation.
|
| 2. Suppose our _model_ of quantum mechanics itself is wrong.
| For example, suppose we live in a universe where some peculiar
| physical collapse theory obtains (it would have to be peculiar
| indeed given the constraints we have on such a thing, but
| presume anyway, for the sake of argument). Then the quantum
| simulation may indeed tell us something that we don't know. If
| you've read Aaronson's book, he sort of suggests this is one of
| the cool things about Quantum Computing: it operates as an
| experimental domain within which some pretty strict limits on
| our quantum theory can be tested. Eg, if we did discover that
| there is a physical collapse of some kind, then one way that
| might happen is with a non-linearity in the Schrodinger
| Equation. But if there is such a non-linearity than it has some
| pretty profound (one might even say absurd) implications for
| what you can get away with with a quantum computer.
| empath-nirvana wrote:
| https://www.newscientist.com/article/mg25934511-300-from-tim...
| jovial_cavalier wrote:
| Don't feel bad. It wouldn't be the first time Quanta engaged in
| such practices.
|
| https://mateusaraujo.info/2022/12/01/the-death-of-quanta-mag...
| pestatije wrote:
| what their saying is a simulation is real if it can
| happen...since you can make a simulation it is real
| bowsamic wrote:
| I haven't read the article but the point is that a quantum
| computer is not a simulation of a quantum system, it is
| completely a quantum system. If you can prove that the dynamics
| and states of your qubits can be mapped onto the system you
| want to simulate, then it is physically equivalent, not just a
| perfect simulation of it. In a sense, the word simulation is a
| bit too weak to describe what is actually going on here,
| possibly the phrase "more convenient example" would be more
| accurate
| gus_massa wrote:
| It's more like using an electrical circuit to make an
| analogic simulation of a spring with a mass (or a pendulum).
| You get the same simplified equation, but each one has
| different nasty corrections. In the case of an electric
| circuit, you are usually ignoring radiation, thermal noise,
| ... In the spring and mass you are usually ignoring the non
| linear part of the spring, air viscosity, tidal forces of the
| moon, ...
| marcosdumay wrote:
| It's like using an electrical circuit to make an analog
| simulation of the behavior of an arbitrary resistor-
| capacitor circuit.
|
| You can get a lot of flexibility from all the extra stuff
| you have controlling your simulator, but the simulator is
| essentially the same thing it is simulating. You don't have
| to ignore anything.
| bowsamic wrote:
| A quantum example of that is how the light in a cavity is
| exactly the same as the mass on a spring but with a
| temperature independent "thermal noise", but only if you
| consider just one mode of that spring, ignore non-linear
| stuff, etc.
| jxramos wrote:
| interesting, some kind of induced physical analogue, or
| induced physical form or something mirroring, behavioral
| state mirroring, physical state mirroring, yes what do we
| call this phenomena. Has almost the feel of how wave energy
| can be found in all sorts of media, fluid, sand, gas, etc.
| Andrew018 wrote:
| Physicists have created elusive particles that can remember their
| pasts. This could lead to new ways to develop quantum computers
| and other quantum technologies. Also, check out AC Football Cases
| VagabundoP wrote:
| I can't picture quantum computers. They make no sense to me.
| Logic gates are just baked into my brain.
| pseudosudoer wrote:
| Once the map between entanglement and exponential parallelism
| is clear, quantum computing becomes a breeze /s. Seriously
| though, entanglement is the root of what makes quantum
| computing useful.
|
| One subset of problems that are solved exponentially faster are
| those that intersect with tensor products. Entanglement
| essentially "is" a tensor product of the probabilistic state
| space of two qubits.
| loa_in_ wrote:
| There is evidence of logic gate analogues in biological neural
| networks, so this might be an analogy or even a straight
| statement of a fact!
| anon____ wrote:
| Scott Aaronson made a comic with Zach Weinersmith that explains
| quantum computing in an entertaining way:
|
| https://www.smbc-comics.com/comic/the-talk-3
| nuancebydefault wrote:
| Wow!
| sidcool wrote:
| So homeopathy was true! /s
| passion__desire wrote:
| But then it is true about everything not just water. \s
| acolderentity wrote:
| Cool
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