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Science

Physicists Link Two Time Crystals In Seemingly Impossible Experiment (livescience.com) 52

An anonymous reader quotes a report from Live Science: Physicists have created a system of two connected time crystals, which are strange quantum systems that are stuck in an endless loop to which the normal laws of thermodynamics do not apply. By connecting two time crystals together, the physicists hope to use the technology to eventually build a new kind of quantum computer. "It is a rare privilege to explore a completely novel phase of matter," Samuli Autti, the lead scientist on the project from Lancaster University in the United Kingdom, told Live Science in an email. [...]

In the new study, Autti and his team used "magnons" to build their time crystal. Magnons are "quasiparticles," which emerge in the collective state of a group of atoms. In this case, the team of physicists took helium-3 -- a helium atom with two protons but only one neutron -- and cooled it to within a ten-thousandth of a degree above absolute zero. At that temperature, the helium-3 transformed into a Bose-Einstein condensate, where all the atoms share a common quantum state and work in concert with each other. In that condensate, all the spins of the electrons in the helium-3 linked up and worked together, generating waves of magnetic energy, the magnons. These waves sloshed back and forth forever, making them a time crystal. Autti's team took two groups of magnons, each one operating as its own time crystal, and brought them close enough to influence each other. The combined system of magnons acted as one time crystal with two different states.

Autti's team hopes that their experiments can clarify the relationship between quantum and classical physics. Their goal is to build time crystals that interact with their environments without the quantum states disintegrating, allowing the time crystal to keep running while it is used for something else. It wouldn't mean free energy -- the motion associated with a time crystal doesn't have kinetic energy in the usual sense, but it could be used for quantum computing. Having two states is important, because that is the basis for computation. In classical computer systems, the basic unit of information is a bit, which can take either a 0 or 1 state, while in quantum computing, each "qubit" can be in more than one place at the same time, allowing for much more computing power.
The research has been published in the journal Nature Communications.
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Physicists Link Two Time Crystals In Seemingly Impossible Experiment

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  • Careful... (Score:5, Informative)

    by dereference ( 875531 ) on Friday June 17, 2022 @11:28PM (#62630476)
    Linking 8 of these time crystals might make a time cube.
  • by gweihir ( 88907 ) on Saturday June 18, 2022 @12:14AM (#62630504)

    Maybe build an old kind first, i.e. one that actually works and not just fakes it...

    • by HiThere ( 15173 )

      They *have* built quantum computers. They just aren't very practical yet. For much of anything. This, needing to be kept at a fraction of a degree Kelvin, doesn't sound any more practical than the others.

      But theoretically it's interesting.

  • "These waves sloshed back and forth forever, ..." They did, did they?
    • "We watched the machine from the outside for ten minutes, but it soon got so boring that it felt like forever."

      Then they went to have a beer and write a paper.

    • To quote TFA:

      The laws of physics are symmetric through space. That means that the fundamental equations of gravity or electromagnetism or quantum mechanics apply equally throughout the entirety of the volume of the universe....But in a crystal, this gorgeous symmetry gets broken.

      No it does not, not even a little. This symmetry is what gives rise to conservation of momentum. It's fundamentally built into Relativity. Breaking this symmetry this would break relativity and nobody is claiming that. If I displace a crystal through space the physics governing it is _exactly_ the same no matter where I place it.

      In 2012, physicist Frank Wilczek, at the Massachusetts Institute of Technology, noticed that the laws of physics also have a time symmetry. That means any experiment repeated at a later time should produce the same result.

      No, he did not - this is something we have known for decades if not a century or more. You learn in undergrad physics when you show using Lagrangian mechanics and Noe

  • It just shows our so called laws of physics aren't nearly as set in stone as some people think they are. They're just a way, though of by humans, to explain stuff, and we know how many times humans get thing wrong. A LOT of times.
    • Re:It just shows... (Score:5, Interesting)

      by DamnOregonian ( 963763 ) on Saturday June 18, 2022 @03:46AM (#62630778)
      There is nothing about this experiment that defies the laws of physics.
      BECs are not new. Being able to play with them is.
      Bringing collections of particles to the ground state and being able to play with macro quantum effects is neat, but none of it is new physics.
      • by HiThere ( 15173 )

        I suspect, though, that the math to predict how they would interact may be too fearsome for anyone tow work through. Much of the details of quantum math is "well, we can't calculate this exactly, so we'll make some simplifying assumptions and hope that it predicts the right answer". Amazingly often it does, but it's not exactly a mathematical certainty. (Check out renormalization.)

  • by OolimPhon ( 1120895 ) on Saturday June 18, 2022 @04:25AM (#62630818)

    Stuff the quantum computer nonsense.

    What I want to know is, having synchronised the two crystals, can they then be separated and used as a communications medium?

    • by HiThere ( 15173 )

      Pretty sure the answer is "no", but I'm also pretty sure that they system isn't stable enough for that to convey more than 1 bit of information. When they say "forever" they probably mean "it was stable for several seconds", which is pretty close to forever for a quantum system. I don't think this "time crystal" has the same kind of forces holding it stable that an ordinary crystal does. Not even approximately the same magnitude. (That they need to keep it a fraction of a degree Kelvin is a pretty good

      • by caseih ( 160668 )

        Diana Cowen, who's a well-known physics youtuber, posted a video describing what they in a bit more detail.

        https://www.youtube.com/watch?... [youtube.com]

        Basically by "forever" they mean as long as the laser was shining at the atoms. However the truly weird aspect is that the laser was that the resonating condensate was not absorbing any of the laser's energy. Quantum physics is truly weird.

        • by caseih ( 160668 )

          Make that Dianna Cowern. Personally I'm waiting for Dr. Sabine Hossenfelder to make a video on the topic. She's good at cutting through the hype and explaining what is really going on and whether it matters all that much. She's become quite a critic of how science is communicated these days. Partly that's the fault of the media, and partly the fault of scientists.

    • by Kartu ( 1490911 )

      Quantum entanglement cannot be used to transfer information. (which makes me wonder about how real that "spooky action at a distance" really is)

      https://en.wikipedia.org/wiki/... [wikipedia.org]

  • Next step is to entangle them then move the half somewhere else.

    • But entangled whatevers have opposing spins don't they? And, as soon as you look at one you immediately know the spin of the other, but now you have ruined it as it is one use because just looking at one changes it's state.

      They try to make entanglement sound like you can influence one by changing the other - as far as I have seen in entanglement articles - it does not work that way.
  • These kinds of experiments will cause Groundhog Day time loops.

  • "Time Crystals" sounds like some kind of 80s show for tweens.
  • by GBH ( 142968 ) on Saturday June 18, 2022 @07:56AM (#62631040)

    of thermodynamics I am so incredibly sceptical as to immediately call bullshit.

    Not impossible as things are proven and disproven all the time, but the first and second laws have proven to be pretty robust up until this point and preclude any kind of perpetual motion machine. I'd suggest this is also true at a quantum level (but lets face it, the quantum physics can be pretty whacky at times).

    Interesting but I'd be very sceptical of claims that the laws of thermodynamics don't apply when they apply to everything else we've looked at.

    • by HiThere ( 15173 )

      Don't be too skeptical. Time crystals have been found, and the assumptions of thermodynamics don't apply to them. But they're also quite small, and with all the pieces in particular quantum states. I *believe* that they're also quite sensitive to external noise.

      Thermodynamics ASSUMES that there's a random distribution of quantum states. (Well, that's a little of an overstatement, but that's the basic idea.) When you don't have that, thermodynamics doesn't apply.

      • Time crystals have been found, and the assumptions of thermodynamics don't apply to them. But they're also quite small, and with all the pieces in particular quantum states. I *believe* that they're also quite sensitive to external noise.

        If so, then perhaps that can be where the energy is coming from to run them.

        • by HiThere ( 15173 )

          IIUC they don't require any external energy source. They also don't emit any external energy. It's a transition between a regular series of states that are all at the same energy. (That said, this example required illumination by a laser, so...)

          • IIUC they don't require any external energy source. They also don't emit any external energy. It's a transition between a regular series of states that are all at the same energy.

            With 100% efficiency, while transmitting information to the outside of the system? I don't think so.

            (That said, this example required illumination by a laser, so...)

            Yeah. And in every other case you will find an external source of energy, too.

    • Ignore things written by confused journalists who don't understand the subjects they're writing about. Put a quantum system into a stationary state and it stays there (as long as you can keep it isolated). Nothing here breaks the laws of thermodynamics. If it spontaneously transitioned to a state of lower entropy, that would be a problem. But it doesn't. It just stays in the same state. Thermodynamics is fine with that.

  • There is no computation without energy, quantum or otherwise. TFS makes no sense.
  • In that condensate, all the spins of the electrons in the helium-3 linked up and worked together, generating waves of magnetic energy...

    Unless the energy you could extract from the waves of magnetic energy created here was somehow greater than the energy required to just maintain the condensate's temperature to stay in that state in the first place, I fail to see how this is that big of a deal.

    • It is not about extracting energy, you don't extract energy from a clock for it to be useful. Imagine what can be done if you could separate the condensate into two or more groups and keep them at-temperature while moving them anywhere in the world while they maintain a perfect timing for use as a clock. Now you have multiple clocks that are always synchronized anywhere in the world.
      • by mark-t ( 151149 )
        Unless the energy that could be extracted from the magnetic energy waves produced by the condensate was somehow greater than the energy expenditure necessary to keep the condensate in that state, I expect that any other alleged usefulness this might otheriwse be suspected to have is unlikely to justify the expenditure of energy required to just keep it at condensate temperature for any purpose that relates to the real world.
  • Not a physicist, not in the least, but it sounds like they discovered/created a quantum oscillator?
  • https://www.youtube.com/watch?... [youtube.com]

    It only works when noone is watching.

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