Hardly a day goes by without someone heralding a “This changes everything!” discovery, news item or invention, but a new study by physicists from Google – yes, Google! – may be the real deal. In a preprint paper which has yet to be peer-reviewed (get the caveats out of the way), researchers at Google, Stanford, Princeton and other universities claim to have used Google’s quantum computer to demonstrate a “time crystal” — an object whose parts move in a regular, repeating cycle without burning any energy. If you think that sounds like a perpetual motion machine, you’re right. Scientists far smarter than this writer say if true, this time crystal violates the second law of thermodynamics (entropy or disorder always increases) while breaking the rule of “time-translation symmetry” (a stable object will remain the same throughout time). We’re still here, so breaking those laws isn’t too bad … right?
A perpetual motion machine in need of a time crystal
“Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC).”
“Here we implement a continuous family of tunable CPHASE gates on an array of superconducting qubits to experimentally observe an eigenstate-ordered DTC. We demonstrate the characteristic spatiotemporal response of a DTC for generic initial states.”
A veritable small town of scientific wizards authored “Observation of Time-Crystalline Eigenstate Order on a Quantum Processor.” Fortunately, we have publications like Quanta Magazine to translate quantum-speak into a language the general public might understand. It does this by comparing time crystals to something we all now – ice crystals. Ice is matter in thermal equilibrium – its atoms have “settled into the state with the lowest energy permitted by the ambient temperature, and their properties don’t change with time.” On the other seemingly impossible hand, time crystals are a new form of matter that’s in an “out-of-equilibrium” phase — it has “order and perfect stability despite being in an excited and evolving state.” In really simple terms, its moving and changing without needing any energy for fuel. Can you think up any situations where this might come in handy?
In 2019, Google announced that its Sycamore quantum computer had completed a task in 200 seconds that would take a conventional computer 10,000 years. That’s when Vedika Khemani, a condensed matter physicist now at Stanford and co-author of the new paper, and her colleagues realized there now existed a computer that could create a time crystal. Coincidentally, the creators of the Sycamore computer were looking for something new to test it. they got together and the rest is history that changes everything. Or does it?
Just because something looks like it should work …
The Sycamore quantum computer uses superconducting aluminum strips as qubits — controllable quantum particles which can maintain two possible states, labeled 0 and 1, at the same time. Each has two possible energy states, which can be programmed to represent spins pointing up or down. Kechedzhi her team used a chip with 20 qubits to serve as the potential time crystal. They ran tens of thousands of demos while fine-tuning the states until the strip became a time crystal.
“These results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors.”
As the report states, the team using Google’s quantum computer proved that humans can create time crystals. Believe it or not, that was the easy part – now they have to figure what to do with them. Warp drive? That’s one possibility. However, there’s one big missing piece – the study and research has not yet been reviewed by peers.
Will it pass the scientific sniff test? Only time – and time crystals – will tell.
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