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Science

Yale Physicists Find Signs of a Time Crystal (yale.edu) 58

Yale physicists have uncovered hints of a time crystal, a form of matter that "ticks" when exposed to an electromagnetic pulse, in a child's toy. The discovery means there are now new puzzles to solve, in terms of how time crystals form in the first place. Yale News reports: Ordinary crystals such as salt or quartz are examples of three-dimensional, ordered spatial crystals. Their atoms are arranged in a repeating system, something scientists have known for a century. Time crystals, first identified in 2016, are different. Their atoms spin periodically, first in one direction and then in another, as a pulsating force is used to flip them. That's the "ticking." In addition, the ticking in a time crystal is locked at a particular frequency, even when the pulse flips are imperfect.

Monoammonium phosphate (MAP) crystals are considered so easy to grow that they are sometimes included in crystal growing kits aimed at youngsters. It would be unusual to find a time crystal signature inside a MAP crystal, [Yale Physics professor Sean Barrett] explained, because time crystals were thought to form in crystals with more internal "disorder." The researchers used nuclear magnetic resonance (NMR) to look for a DTC signature -- and quickly found it. Another unexpected thing happened, as well. "We realized that just finding the DTC signature didn't necessarily prove that the system had a quantum memory of how it came to be," said Yale graduate student Robert Blum, a co-author on the studies. "This spurred us to try a time crystal 'echo,' which revealed the hidden coherence, or quantum order, within the system," added Rovny, also a Yale graduate student and lead author of the studies.
The findings are described in a pair of studies, one in the journal Physical Review Letters and the other in the journal Physical Review B.
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Yale Physicists Find Signs of a Time Crystal

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  • by rossdee ( 243626 ) on Friday May 04, 2018 @10:19PM (#56557332)

    Call The Doctor

  • by Anonymous Coward

    discrete time crystal

  • Hmmm... that's Interesting.

    it's what we teach our techs to say at a customer's location when something goes awry, rather than "oh shit". It also fits when the conversational topic is above my pay grade.

  • So, they're "locked at a particular frequency."

    How accurate is it? Is it better than atomic transitions (hydrogen maser, cesium or rubidium clock), or even as good as a quartz or ceramic oscillator?

    I scanned the links, with no obvious answer.

    It's interesting in and of itself, but that's the first practical application which comes to mind. Are there other applications I'm missing?
    • The only real-world application is for a metronome.
    • Re:Timekeeping. (Score:4, Interesting)

      by hey! ( 33014 ) on Friday May 04, 2018 @11:15PM (#56557492) Homepage Journal

      I think you mean to ask how *precise* it is. The mentioned applications (atomic clocks, laser gyros) are all precision applications.

      Many practical applications would depend on being able to manufacture crystals that have a specific desired frequency,. For example quartz timepieces employ a quartz crystal that is machined by lasers or polishing to have a precise resonant frequency of 2^15 (32768) Hz, enabling one watch after another to keep precisely the same time. You just route the oscillator output through 15 frequency dividers and you get a 1 second signal to drive a stepper motor.

      But we're talking about is a more exotic process and it's not clear you could tweak time crystals that way.

      There's been recent work to develop chip-sized atomic clocks. These are more precise than quartz but could be use on battery-powered circuit boards. This kind of application would requiring mass producing time crystals with the same frequency, even if it wasn't a convenient one like 2^15.

      • by msauve ( 701917 )
        No, I mean accurate. Cs is perfectly accurate, by definition (acceleration and temperature excepted for physical realizations), although H maser is more precise. Precision matters short term, accuracy long term.

        But, despite a lengthy attempt at being pedantic, you haven't even come close to answering the question. What's the intrinsic accuracy of (these) time crystals? Do separate ones differ? Temperature/pressure/humidity effects? Gravity orientation? Level of excitation? Aging? Retrace?
        • by hey! ( 33014 )

          Yes, I was pedantic, because your question is broken if you don't understand the difference between accurate and precise, which you clearly don't.

      • Many practical applications would depend on being able to manufacture crystals that have a specific desired frequency

        Not really. Once you have a precise base frequency, you can fairly easily generate other frequencies that are just as precise. The reason that watches use 32kHz is mostly tradition, a leftover relic from the days that semiconductors were still hard to make.

        • by hey! ( 33014 )

          Sure, you're correct nowt that circuitry is cheap. But really what you need is something precise and repeatably manufacturable..

          • by lgw ( 121541 )

            The point is: do they all have the same frequency, without precision manufacturing? If so, "same" to how many significant digits?

            I've always been amused by the fact that cesium clocks are exact (by definition), yet the underlying mechanism is random. I guess the variance is far below what anyone would ever care about.

    • Re:Timekeeping. (Score:4, Interesting)

      by slew ( 2918 ) on Saturday May 05, 2018 @12:07AM (#56557700)

      The difference between an oscillator and a time crystal, is that an oscillator generally has a resonant spatial structure (usually a spatial crystal or atomic band-gaps) that captures energy (near a resonate frequency or harmonic) and converts it to work near a preferred oscillation frequency. Since the oscillation is actually physical transition with inefficiencies mean that there is a limited 'Q' factor [wikipedia.org]

      A time crystal on the other hand is an emergent temporal sub-harmonic structure. Since a time crystal does not require a spatial structure to convert energy into work there is the potentiality for them to have a much better 'Q' factors.

      The interesting thing about time crystals is that locally they break time-symmetry like spatial crystals break local spatial symmetry.

      Spatial crystals break local spatial symmetry so spatial interactions (translational or rotational) between particles and stable spatial crystals can change momentum of the particles in stable ways because of conservation of momentum (which is basically of how typical electronic oscillators work) being an emergent property of spatial symmetry (Noether's theorem)

      Time crystals break local temporal symmetry so temporal interactions between particles and stable time crystals can directly change the energy of the particles in stable ways because of conservation of energy being an emergent property of temporal symmetry.

      • Great whitepaper!

        Do DTCs break time symmetry because of their local (in time) -based oscillations that are not atomic, but rather sub-atomic?

        Why do we have a constant velocity along the time axis in this universe (under non-relativistic conditions)?

        Maybe we oscillate between Big Bangs and Big Crunches over the billions off years... Oh yeah, there is no time before the Big Bang, which started the clock. Bah! I'll stick to crystals.

        • by slew ( 2918 )

          Do DTCs break time symmetry because of their local (in time) -based oscillations that are not atomic, but rather sub-atomic?

          *Crystals* break local symmetries. It has nothing to do with atomic vs sub-atomic. Normally the laws of physics don't respect a specific orientation, or phase, but in a crystal, for some reason a system can be in a state that prefers a particular set of orientations or phases, that is what we call a crystal.

          Why do we have a constant velocity along the time axis in this universe (under non-relativistic conditions)?

          If you want to be pedantic, dt/dt (the change in the rate of time over the change in the rate of time) is always constant. "We" only assume that other observers see our time the same as "we" do. It t

  • by slew ( 2918 ) on Friday May 04, 2018 @10:44PM (#56557406)

    Apparently, slashdot posted a few submissions last year where
    Harvard and University of Maryland [slashdot.org] managed to do this as well as Princeton [slashdot.org].

    I suppose Yale was destined to get around to this eventually, I suppose they just needed more time...

    • I suppose Yale was destined to get around to this eventually, I suppose they just needed more time...

      Or maybe they got to it first. Now that time crystals are a thing, how can we be certain. Personally I blame Obama. This never would have happened if Romney won the election. Thank god we only have another year of him, and it's not like Obama will win a second term.

      • by aix tom ( 902140 )

        Well, I for one look forward to the second campaign between Sasha and Craig. I wonder how they propose to solve the Switzerland issue.

  • Turns out it was right next to the Time Cube.
  • Huh? (Score:2, Interesting)

    by Anonymous Coward

    We realized that just finding the DTC signature didn't necessarily prove that the system had a quantum memory of how it came to be

    What the actual goddamned fucking hell is that supposed to mean?!

    Some hippy crystal shit right there. Like, the universe remembers, man.

    Quantum physics still makes no sense, I could barely find one sentence in that summary I even understood, and it still makes no sense.

    Is this shit actually science or is it gibberish like string theory?

    • "What the actual goddamned fucking hell is that supposed to mean?! Some hippy crystal shit right there. Like, the universe remembers, man."

      It means like, anything you want it to, man.

    • And all of that in a childs toy!

      The summary does not make sense either.

    • by Z80a ( 971949 )

      Don't worry, everything will make sense when they make a cube out of it.
      A time cube if you will.

  • by Anonymous Coward

    The chances of a resonance cascade scenario are highly unlikely. They assured the administrator that nothing would go wrong...

  • My 1980 quartz crystal watch...
  • Yes, it's called quartz, you apply a current, it "ticks" in a very precise interval .... OMG.
  • What would happen if someone placed time crystals in a Ocarina and blew on it?

  • by Anonymous Coward

    Now the kits can say "Grow Your Own TIME Crystals"

  • When I read that title, I thought they found some kind of time-traveling crystal. Oh well... back to the future I suppose...

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