Time Crystal Quantum Computer

Time Crystal Quantum

Stanford physicists help create time crystals with quantum computers

A team of researchers including ones from Stanford and Google have created and observed a new phase of matter, popularly known as a time crystal. 

BY TAYLOR KUBOTA

There is a huge global effort to engineer a computer capable of harnessing the power of quantum physics to carry out computations of unprecedented complexity. While formidable technological obstacles still stand in the way of creating such a quantum computer, today’s early prototypes are still capable of remarkable feats.

The Google Sycamore chip used in the creation of a time crystal. (Image credit: Google Quantum AI)

For example, the creation of a new phase of matter called a “time crystal.” Just as a crystal’s structure repeats in space, a time crystal repeats in time and, importantly, does so infinitely and without any further input of energy – like a clock that runs forever without any batteries. The quest to realize this phase of matter has been a longstanding challenge in theory and experiment – one that has now finally come to fruition.

In research published Nov. 30 in Nature, a team of scientists from Stanford University, Google Quantum AI, the Max Planck Institute for Physics of Complex Systems and Oxford University detail their creation of a time crystal using Google’s Sycamore quantum computing hardware.

“The big picture is that we are taking the devices that are meant to be the quantum computers of the future and thinking of them as complex quantum systems in their own right,” said Matteo Ippoliti, a postdoctoral scholar at Stanford and co-lead author of the work. “Instead of computation, we’re putting the computer to work as a new experimental platform to realize and detect new phases of matter.”

For the team, the excitement of their achievement lies not only in creating a new phase of matter but in opening up opportunities to explore new regimes in their field of condensed matter physics, which studies the novel phenomena and properties brought about by the collective interactions of many objects in a system. (Such interactions can be far richer than the properties of the individual objects.)

“Time-crystals are a striking example of a new type of non-equilibrium quantum phase of matter,” said Vedika Khemani, assistant professor of physics at Stanford and a senior author of the paper. “While much of our understanding of condensed matter physics is based on equilibrium systems, these new quantum devices are providing us a fascinating window into new non-equilibrium regimes in many-body physics.”

What a time crystal is and isn’t

The basic ingredients to make this time crystal are as follows: The physics equivalent of a fruit fly and something to give it a kick. The fruit fly of physics is the Ising model, a longstanding tool for understanding various physical phenomena – including phase transitions and magnetism – which consists of a lattice where each site is occupied by a particle that can be in two states, represented as a spin up or down.

During her graduate school years, Khemani, her doctoral advisor Shivaji Sondhi, then at Princeton University, and Achilleas Lazarides and Roderich Moessner at the Max Planck Institute for Physics of Complex Systems stumbled upon this recipe for making time crystals unintentionally. They were studying non-equilibrium many-body localized systems – systems where the particles get “stuck” in the state in which they started and can never relax to an equilibrium state. They were interested in exploring phases that might develop in such systems when they are periodically “kicked” by a laser. Not only did they manage to find stable non-equilibrium phases, they found one where the spins of the particles flipped between patterns that repeat in time forever, at a period twice that of the driving period of the laser, thus making a time crystal.  ... 

Google Makes a Time Crystal

 Idea is new to me, but reminded me of some 'forever clock' ideas that were brought up in the 80s with the 'Long Now' effort.  See the tag.   Is this at all related?    Do you 'evade the second law of thermodynamics"?  and make it go the way of action at a distance?

Eternal Change for No Energy: A Time Crystal Finally Made Real  In QuantaMagazine.

Like a perpetual motion machine, a time crystal forever cycles between states without consuming energy. Physicists claim to have built this new phase of matter inside a quantum computer.

In a preprint posted online Thursday night    , researchers at Google in collaboration with physicists at Stanford, Princeton and other universities say that they have used Google’s quantum computer to demonstrate a genuine “time crystal.” In addition, a separate research group claimed earlier this month to have created a time crystal in a diamond.

A novel phase of matter that physicists have strived to realize for many years, a time crystal is an object whose parts move in a regular, repeating cycle, sustaining this constant change without burning any energy.

“The consequence is amazing: You evade the second law of thermodynamics,” said Roderich Moessner, director of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, and a co-author on the Google paper. That’s the law that says disorder always increases.

Time crystals are also the first objects to spontaneously break “time-translation symmetry,” the usual rule that a stable object will remain the same throughout time. A time crystal is both stable and ever-changing, with special moments that come at periodic intervals in time.

The time crystal is a new category of phases of matter, expanding the definition of what a phase is. All other known phases, like water or ice, are in thermal equilibrium: Their constituent atoms have settled into the state with the lowest energy permitted by the ambient temperature, and their properties don’t change with time. The time crystal is the first “out-of-equilibrium” phase: It has order and perfect stability despite being in an excited and evolving state.

“This is just this completely new and exciting space that we’re working in now,” said Vedika Khemani, a condensed matter physicist now at Stanford who co-discovered the novel phase while she was a graduate student and co-authored the new paper with the Google team.

Khemani, Moessner, Shivaji Sondhi of Princeton and Achilleas Lazarides of Loughborough University in the United Kingdom discovered the possibility of the phase and described its key properties in 2015; a rival group of physicists led by Chetan Nayak of Microsoft Station Q and the University of California, Santa Barbara identified it as a time crystal soon after.

Researchers have raced to create a time crystal over the past five years, but previous demos, though successful on their own terms, have failed to satisfy all the criteria needed to establish the time crystal’s existence. “There are good reasons to think that none of those experiments completely succeeded, and a quantum computer like [Google’s] would be particularly well placed to do much better than those earlier experiments,” said John Chalker, a condensed matter physicist at the University of Oxford who wasn’t involved in the new work.

The cryostat used to hold Google’s quantum processors.

Google

Google’s quantum computing team made headlines in 2019 when they performed the first-ever computation that ordinary computers weren’t thought to be able to do in a practical amount of time. Yet that task was contrived to show a speedup and was of no inherent interest. The new time crystal demo marks one of the first times a quantum computer has found gainful employment.  ... '