27 votes
Accepted

Understanding time crystals

The key idea is that time crystals are externally driven at a certain frequency, but they respond at a different (in fact, slower) frequency. First of all, terminology: what does it have in common ...
user avatar
  • 41.3k
13 votes
Accepted

What could time crystals be useful for?

This is a review article on the status of the research by summer of 2017. I copy the conclusions: In the present article we have reviewed current state of the art of investigations of time ...
user avatar
  • 220k
11 votes
Accepted

What's the difference between a time crystal and a system undergoing periodic motion?

A crystal is a system which spontaneously breaks the translation symmetry of the underlying physical laws. Similarly, a time crystal is a system which is subject to a periodic driving with period $T$,...
user avatar
2 votes

Time crystals: fake or revolution?

A flaw in Wilczek's argument has been pointed out in PRL 110, 118901 (2013). In short, the rotating soliton exhibited by Wilczek is not the correct ground state of the system. The true ground state ...
user avatar
  • 158
2 votes
Accepted

Time Crystals - Question on the Hamiltonian for space crystals as in the seminal paper

In the first example with potential $V_1(\phi)$, the symmetry being broken is the spatial translation symmetry, $x \rightarrow x + a$. The potential doesn't change under this transformation, but since ...
user avatar
  • 6,135
2 votes

Do time crystals require quantum entanglement?

It depends entirely on your exact definitions. Many times, someone has proposed a "classical time crystal", but then someone else has argued that that isn't a "true" time crystal because it's time ...
user avatar
  • 41.3k
1 vote
Accepted

Quantum Time Crystals

He is referring to a more precise definition of order parameter. The idea is to capture spontaneous symmetry breaking: the ground states of the system are not individually invariant under the ...
user avatar
  • 1,145
1 vote

What does it mean to be less symmetrical than the equations governing the system?

An example would a Lennard Jones crystal. In two dimensions, at low enough temperature, it forms a hexagonal phase Yet in the Hamiltonian there is nothing that hints at 6-fold symmetry at all. The ...
user avatar
1 vote
Accepted

Do time crystals require quantum entanglement?

A quantum time crystal does not from my reading of Wilczek and others appear to require entanglement, but the idea is interesting. It does seems plausible that a quantum time crystal model could be ...
user avatar
1 vote
Accepted

Trying to understand crystal structures within a solid

Let me try to explain with an example. Let's consider for instance the honeycomb lattice shown below. What type of lattice is this? Now since this is a two dimensional structure, we might expect that ...
user avatar
  • 1,551
1 vote

Why cant time-crystals form in thermal equilibrium?

If you consult the September, 2018, issue of Physics Today you will find an excellent article on time crystals by N Yao and C Nayak (p 41). Paraphrasing their synopsis, time crystals result when the ...
user avatar
  • 5,473
1 vote

Could spacetime have crystalline properties?

I am going to make this brief. As pointed out space has a crystalline structure in LQG. This has some odd problems in that it violates Lorentz invariance on scales close to the scale length of the ...
user avatar

Only top scored, non community-wiki answers of a minimum length are eligible