Two articles

Scientists Have Confirmed a Brand New Phase of Matter: Time Crystals

DARPA Is Researching Time Crystals, And Their Reasons Are ‘Classified’

Tau.Neutrino said:

Two articles

Scientists Have Confirmed a Brand New Phase of Matter: Time Crystals

DARPA Is Researching Time Crystals, And Their Reasons Are ‘Classified’

> strange crystals that have an atomic structure that repeats not just in space, but in time, putting them in constant oscillation without energy.

What’s the difference between that and a ferromagnet. And an antiferromagnet.

> Imagine it like jelly – when you tap it, it repeatedly jiggles. The same thing happens in time crystals, but the big difference here is that the motion occurs without any energy.

That happens in rotating superfluids.

> The University of Maryland’s time crystals were created by taking a conga line of 10 ytterbium ions, all with entangled electron spins. The key to turning that set-up into a time crystal was to keep the ions out of equilibrium, and to do that the researchers alternately hit them with two lasers. One laser created a magnetic field and the second laser partially flipped the spins of the atoms.

Just like a ferromagnet or antiferromagnet so far. Mind you, 10 atoms isn’t a very bit piece of material.

> The two lasers that were periodically nudging the ytterbium atoms were producing a repetition in the system at twice the period of the nudges, something that couldn’t occur in a normal system.

Sounds familiar from somewhere.

> The Harvard time crystal was different. The researchers set it up using densely packed nitrogen vacancy centres in diamonds, but with the same result.

It’s not unusual to have a material that vibrates at a frequency different to that of the driving frequency.

For example nonlinear crystals and their use in frequency doubling.

“Practically, frequency doubling is carried out by placing a nonlinear medium in a laser beam. While there are many types of nonlinear media, the most common media are crystals. Commonly used crystals are BBO (β-barium borate), KDP (potassium dihydrogen phosphate), KTP (potassium titanyl phosphate), and lithium niobate. These crystals have the necessary properties of being strongly birefringent (necessary to obtain phase matching), having a specific crystal symmetry, being transparent for both the impinging laser light and the frequency-doubled wavelength, and having high damage thresholds, which makes them resistant against the high-intensity laser light.”