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Time crystals? – crystal patterns in space and time

John Healy

Frank Wilczek referenced this topic – time crystals – in his latest book (Fundamentals: Ten Keys to Reality).

Time crystals are physical systems that spontaneously settle into stable loops of behavior. I proposed this concept in 2012, and many interesting examples have been discovered since then, both theoretically and experimentally.

A recent example is close to my heart: It may be possible to orchestrate large numbers of atoms, cooperating within a new state of matter that I predicted and that was subsequently observed — a “time crystal” — to improve on the accuracy of single-atom atomic clocks. – Wilczek, Frank. Fundamentals. Penguin Publishing Group. 2021. Kindle Edition.

Recent references on the topic inspired this post. Like “Black Holes,” another zippy name for a peculiar phenomenon. In condensed matter physics. And yet another behavior related to expanding research in quasiparticles.

Wiki:

A common crystal form is an atomic lattice structure that extends in all directions with a great deal of symmetry, but not perfectly so. Its asymmetry—known amongst researchers as symmetry breaking—occurs in crystals even though the laws of physics are spatially symmetrical. As the laws of physics are symmetrical in time as well as space, the question arose as to whether it is possible to break symmetry temporally and thus create a “time crystal” resistant to entropy. A discrete time crystal has in fact been observed in physics laboratories as early as 2016. One example of a time crystal which demonstrates non-equilibrium, broken time symmetry is a constantly rotating ring of charged ions in an otherwise lowest-energy state.

Here’s a recent article, which includes a brief recap and visualization of this phenomenon.

• Sci Tech Daily > “See World’s First Video of a Space-Time Crystal” by Max-Planck-Gesellschaft (February 24, 2021)

• YouTube > MaxPlanckSociety > Space-Time Crystal (Feb 11, 2021)

A team of researchers [published in the Physical Review Letters] has succeeded in creating a micrometer-sized space-time crystal consisting of magnons at room temperature. With the help of an ultra-precise X-ray microscope [/ camera, imaging at up to 40 billion frames per second], they were able to capture the recurring [pattern of] periodic magnetization structure in a movie.

In their experiment, Gruszecki and Träger [Max Planck Institute for Intelligent Systems] placed a strip of magnetic material on a microscopic antenna through which they sent a radio-frequency current. This microwave field triggered an oscillating magnetic field, a source of energy that stimulated the magnons in the strip – the quasiparticle of a spin wave. Magnetic waves migrated into the strip from left and right, spontaneously condensing into a recurring pattern in space and time. Unlike trivial standing waves, this pattern was formed before the two converging waves could even meet and interfere. The pattern, which regularly disappears and reappears on its own, must therefore be a quantum effect.

One thought on “Time crystals? – crystal patterns in space and time”

  1. Analogies for quasiparticles?

    • Britannica > Quasiparticle

    Quasiparticle, in physics, a disturbance, in a medium, that behaves as a particle and that may conveniently be regarded as one. A rudimentary analogy is that of a bubble in a glass of beer: the bubble is not really an independent object but a phenomenon, … the bubble retains a certain identity … [with] properties characteristic of objects, such as size, shape, energy, and momentum. [But unlike true quasiparticles, each bubble is not identical, i.e. quantized.]

    There is reason to suspect … that all particles may actually be disturbances in some underlying medium and, hence, are themselves quasiparticles.

    [See Related posts (below) re “particles” as defects in a medium.]

    • Ask Mathemmatician > “What are quasi-particles? Why do phonons and photons have such similar names?” (posted on July 22, 2013 by The Physicist)

    One of the more commonly seen quasi-particles is the “electron hole”, which is just a notably absent electron.

    Visual: the missing tile puzzle

    Puzzle

    [Caption] The tiles are real things, but the vacant square is just a conserved effect. It moves and acts a lot like a particle that can wander around the grid. It’s a kind of “quasi-tile”. It’s easier to keep track of the one quasi-tile than to keep track of the 15 real-tiles.

    And phonons.

    … in a crystal all of the atoms are in the same situation and will have identical energy-level-ladders.

    Now say that an atom [in a crystal] is vibrating one level up from the ground state [e.g., excited by a tuned laser]. Since the only state the energy can drop to is the ground state, this vibration is all-or-nothing. The atom can’t give away part of the energy and just vibrate a little less. When the atom does give up its kinetic energy it stops vibrating and an atom next-door picks up that energy (all of that energy) and starts oscillating in turn.

    This one-step-up-from-the-ground-state vibration that passes from place to place is called a “phonon”. The amount of energy in the levels changes depending on exactly how the atoms are held together, so different kinds of crystals will host slightly different phonons, …

    Photons are the smallest possible excited states of the electromagnetic field and are the smallest unit of light, while phonons are the smallest possible excited states of the mechanical system made up of atoms in a crystal and are the smallest possible unit of sound.

    Related posts

    • Comments > A force-less physics?

    (quote) Topological defects are not only stable against small perturbations, but cannot decay or be undone or be de-tangled, precisely because there is no continuous transformation that will map them (homotopically) to a uniform or “trivial” solution.

    (quote) The value of each field [in the Grid] is constantly fluctuating at short distances. Out of these fluctuating fields and their interactions, the vacuum state emerges. Particles are disturbances in this vacuum state. We can picture them as small defects in the structure of the vacuum.

    My note > [1] The notion of “particles” as defects (or topological defects) is something that I’ve been pondering since reading about solitons, as noted in [1][2] for the above comment (June 3, 2020). As sort of “knots” or “twists” in spacetime energy that only can be de-tangled (or created or destroyed) by energetic interactions.

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