Google’s ‘time crystals’ could be a breakthrough for quantum computers

Time crystals sound like majestic objects from sci-fi movies that open passages to alternate universes. In the Marvel Universe, the “Time Stone” gives wielders control over the past, present, and future.

Although it remains a fantasy, scientists have been successfully creating micro-scale time crystals for years – not to power intergalactic spaceships, but to power ultra-powerful computers.

“Time crystals are like a stopover on the road to building a quantum computer,” said Norman Yao, a molecular physicist at the University of California, Berkley.

It’s an area of ​​interest for Google, which, along with physicists from Stanford and Princeton universities, says it has developed an “evolutionary approach” to creating time crystals using the company’s Sycamore quantum computer. society.

In a paper published last month on the research-sharing platform Arxviv.org, a team of more than 100 scientists describe how they put together an array of 20 quantum particles, or qubits, to act as a time crystal. During the experiments, they applied algorithms that rotated qubits up and down, generating a controllable reaction that could be sustained “for infinitely long times,” according to the paper.

Time crystals are scientific oddities made up of atoms arranged in a repeating pattern in space. This design allows them to change shape over time without wasting energy or overheating. Since time crystals are constantly evolving and don’t seem to require much energy, they can be useful for quantum computers, which rely on extremely fragile qubits that are susceptible to decay.

Quantum computing is burdened with hard-to-control qubits that are error-prone and often die. Time crystals could introduce a better method to support quantum computing, according to Yao, who published a blueprint for making time crystals in 2017.

“Time crystals are a weighted benchmark, showing that your system has the required level of control,” Yao said.

Scientists involved in Google’s research say they cannot discuss their findings because they are subject to peer review.

However, the work touches on an area where physicists have long hoped for a breakthrough.

“The consequence is amazing: you’re evading the second law of thermodynamics,” Roderich Moessner, co-author of the Google paper, told Quanta Magazine.

The concept of a time crystal was first proposed in 2012 by Nobel Prize-winning physicist Frank Wilczek, who wondered if atoms could be arranged in time in the same way as in ordinary crystals.

Essentially, he wondered if a closed system could rotate, oscillate, or move repeatedly. What followed was a fair amount of scrutiny from the wider physics community, years of academic experimentation with and without Wilczek, and testing to see if his vision was possible.

The definition was expanded to include objects that would activate due to an external influence, such as shaking, shaking, or laser strike.

“The definition is somewhat fluid. But if you want to call it a new state of matter, you want it to be self-contained and there’s no fuss,” Wilczek said.

Early experiments pumped ions with lasers to vibrate artificially. It was useful but hard to scale, Wilczek added.

In 2017, scientists from Harvard University and the University of Maryland revealed that they had created microscale time crystals at freezing temperatures in a lab. Both have passed peer review. More recently, a team from the Delft University of Technology in the Netherlands published their findings in July on their approach to building a time crystal inside a diamond. (These findings have not been peer reviewed.)

Time crystals are a difficult concept to grasp, but scientists say you can think of them as a perpetual motion machine, adding a caveat to the second law of thermodynamics, which states that any isolated system will degenerate into a state or more disordered entropy. Their existence also undermines Newton’s First Law of Motion, detailing how an object should respond to motion.

Time crystals are the first objects created that spontaneously break “time translation symmetry” or the idea that a stable object, such as solids, liquids, gases, and plasma, will remain the same over time.

Google’s work produced a time crystal that worked for milliseconds, but the research looks promising, Wilczek said. The assumption is that once the hardware becomes more advanced, the resulting time crystals will last longer, he added.

“Nothing lasts forever, not even diamonds, their protons will eventually decay,” Wilczek said. “If you can create something that has time-crystal behavior that lasts for millions of cycles, even thousands of cycles, it can support sensitive technologies. You can do a lot even if it’s not perfect.”

A pedestrian walks past the Google Store Chelsea in New York on May 28, 2021. (Victor J. Blue/Bloomberg)