[HN Gopher] For the First Time, Physicists Have Filmed the Oscil...
___________________________________________________________________
For the First Time, Physicists Have Filmed the Oscillation of a
Time Crystal
Author : IFR
Score : 94 points
Date : 2021-03-02 10:53 UTC (12 hours ago)
(HTM) web link (www.sciencealert.com)
(TXT) w3m dump (www.sciencealert.com)
| seism wrote:
| Far out! Here is the 13 second video from the Max Planck Society
| in all its glory: https://youtu.be/kUY3TglEUCU
| koolba wrote:
| That is cool!
|
| I've never seen such a weird aspect ratio on YouTube either.
| techrat wrote:
| Honestly, the video just looks like someone re-inverted an
| image several times over using a fade. What am I missing?
| airstrike wrote:
| > Time crystals should be stable and coherent over long time
| periods, because they - theoretically - oscillate at their
| lowest possible energy state. The team's research shows that
| driven magnonic time crystals can be easily manipulated,
| opening a new way to reconfigure time crystals. This could
| open up the state of matter for a range of practical
| applications.
|
| > "Classical crystals have a very broad field of
| applications," said physicist Joachim Grafe of the Max Planck
| Institute for Intelligent Systems.
|
| > "Now, if crystals can interact not only in space but also
| in time, we add another dimension of possible applications.
| The potential for communication, radar or imaging technology
| is huge."
| 867-5309 wrote:
| >filmed at up to 40 billion frames per second
|
| that's quite a feat on anyone's watch
| bluefirebrand wrote:
| It probably was filmed on a camera not a watch.
| allemagne wrote:
| >"Now, if crystals can interact not only in space but also in
| time, we add another dimension of possible applications. The
| potential for communication, radar or imaging technology is
| huge."
|
| Could anyone expand on this in an accessible way? What kinds of
| changes could we see in imaging or communication technology?
| armada651 wrote:
| How do Time Crystals differ from the quartz crystals used for
| time keeping in electronics? Is the only difference that Time
| Crystals oscillate without needing an electric field?
| dhdc wrote:
| From my very limited knowledge of physics, time crystals can
| theoretically oscillate forever without any excitation at their
| ground state, though laws of theromodynamics are not broken and
| energy cannot be extracted from their oscillations. In a normal
| crystal oscillater, power is needed to keep the crystal
| oscillating.
| yccs27 wrote:
| Normally, a system (like a quartz) which is driven by an
| external frequency, oscillates at the same or a multiple of the
| driving frequency. This is because the external conditions are
| symmetric under a time translation (i.e. a delay) by the period
| duration. This symmetry is normally preserved by the system.
|
| A time crystal, however, will oscillate with a fraction (or
| rational multiple) of the driving frequency. This breaks the
| original time translation symmetry.
| mjfl wrote:
| I also wonder how a time crystal is different from a harmonic
| oscillator.
| yccs27 wrote:
| Since the article doesn't do a good job of explaining what a time
| crystal _is_ , here's my attempt at summarizing the Wikipedia
| article.
|
| Normally, a system which is driven by an external frequency,
| oscillates at the same or a multiple of the driving frequency.
| This is because the external conditions are symmetric under a
| time translation (i.e. a delay) by the period duration. This
| symmetry is normally preserved by the system.
|
| A time crystal, however, will oscillate with a fraction (or
| rational multiple) of the driving frequency. This breaks the
| original time translation symmetry.
|
| The analogy with normal 'spatial' crystals is through this
| symmetry breaking: Empty space is symmetric under all
| translations, but a crystal spontaneously breaks the symmetry
| group down to the smaller set of 'translations by a multiple of
| the lattice constant'.
|
| The continuous symmetry of time translations cannot be
| spontaneously broken, due to thermodynamic arguments. Instead, we
| explicitly break down the time translation symmetry to 'delays by
| a multiple of the period duration'. A time crystal then
| spontaneously breaks the symmetry down even further, by
| multiplying the period duration / dividing the frequency.
| centimeter wrote:
| How does this compare to the behavior of nonlinear optical
| crystals like lithium triborate? They are also pumped at a
| lower frequency (e.g. 1064nm photons) but lase at twice that
| (532nm).
| yccs27 wrote:
| In some way, it's the inverse: a nonlinear optical system can
| multiply frequencies, while a time crystal divides a
| frequency. That's not as easy as multiplying, due to the
| symmetry concerns I mentioned.
|
| It's basically a frequency divider, but as a system of cold
| atoms instead of an electronic circuit, and in a different
| frequency regime.
| victorevector wrote:
| haha I cant wait to hear about this from my local rock/crystal
| dealer ooommmmmmmm shiva Shankarrrr mahatmahariiii ganjaaaaaa
| gubby wrote:
| Another scummy website that hijacks the back button. I wish there
| were a way to block domains from the results I see on HN.
| tait wrote:
| Does anybody else agree the name "Time Crystal" could be better
| somehow?
| [deleted]
| 867-5309 wrote:
| yes, it sounds too mystic for science
| jhloa2 wrote:
| I like how much it sounds like futuristic science fiction
| technology!
| tobmlt wrote:
| Frank Wilczek was hoping for a writers credit on the next
| Indiana Jones reboot.
| Topgamer7 wrote:
| But then how would I think about Crash Bandicoot and Neo Cortex
| whenever there is news!
| nabla9 wrote:
| No. It's technically very accurate name.
| https://en.wikipedia.org/wiki/Time_crystal
| chadcmulligan wrote:
| I always think of doctor who when I hear it - not that its a
| bad thing.
| how2cflags wrote:
| TimeSplitters Future Perfect - Cortez, get the time crystals!
| tryonenow wrote:
| In the experiment, the crystals were driven by RF excitation. Do
| time crystals generally require a constant energy source to
| oscillate? I would assume not, since they're called crystals...
|
| Also, is the oscillation frequency temperature dependent?
| yccs27 wrote:
| Unfortunately, time crystals do require an external excitation.
| The key is that the excitation does not have the same frequency
| as the time crystal.
| smartestdumbguy wrote:
| I wonder how this links in to optical crystals? KTP, used in
| solid state lasers, will halve the frequency of a IR laser
| (1064nm) to produce green light (532nm).
|
| I suppose this is equivalent to adding electrical energy to a
| crystal to make it oscillate.
| darkwater wrote:
| When quantum mechanics are involved, I feel like someone from 400
| years ago might feel today using a smartphone. And probably as a
| society we are now like starting to experiment with electricity.
| I wonder what will be the smartphones in that future.
| auntienomen wrote:
| These physicists have never properly acknowledged the prior work
| of Otis Eugene Ray on this subject. How typical!
___________________________________________________________________
(page generated 2021-03-02 23:00 UTC)