The new quantum computing architecture creates a time crystal, which has a lifetime 10 times longer than Google's experiment
Norman Yao, a physicist at the University of California, Berkeley (UCB), first described how to make a time crystal five years ago - a new form of matter whose patterns repeat in time rather than space. Although a completely isolated time crystal can live forever in principle, the time crystal created in previous experiments only exists for a fraction of a second.
In July 2021, a research team led by Google created a time crystal using a quantum computer for the first time, which lasted about eight tenths of a second. This time, researchers from Yao and qutech in the Netherlands used a diamond based quantum computer, which lasted about 8 seconds and lived 10 times longer than Google's experiment.
In a paper published in the journal Science on November 4 [1], Yao and qutech researchers reported the creation of a multi-body localized discrete-time crystal, which lasted about 8 seconds, equivalent to 800 oscillation cycles. Qutech is a cooperative project between Delft University of technology and TNO, an independent research institution in the Netherlands. They used a diamond based quantum computer, in which the qubit is the nuclear spin of the carbon-13 atom embedded in the diamond.
Joe Randall of qutech explained: "although a completely isolated time crystal can live forever in principle, any real experiment will decay due to its interaction with the environment. Further prolonging its life is the next frontier."
The results were first published on arXiv this summer. In addition, researchers from Google, Stanford and Princeton copied them in almost simultaneous experiments using Google's superconducting quantum computer "sycamore". The demonstration used 20 qubits made of superconducting aluminum tape and lasted about eight tenths of a second. The time crystals created by Google and qutech using quantum computers are called the Floquet phase of matter, which is a non-equilibrium material.
"It's extremely exciting that multiple experimental breakthroughs occur at the same time. All these different platforms complement each other. Google's experiment uses more than twice as many qubits; our time crystal life is about 10 times longer," said Tim taminiau, chief researcher of qutech.
Qutech's team manipulated nine carbon-13 qubits in the right way to meet the standard of forming multi-body localized time crystals.
Norman Yao, an associate professor of physics at the University of California, Berkeley, said: "the time crystal may be the simplest example of the nonequilibrium phase of matter. The qutech system is fully capable of exploring other nonequilibrium phenomena, such as the Floquet topological phase."
These results were obtained after another crystal observation published in the journal Science a few months ago [2], and Yao's team also participated in this observation. There, the researchers observed a so-called preheating time crystal, in which the subharmonic oscillation is stabilized by high-frequency driving. The experiment was carried out in the Monroe Laboratory of the University of Maryland. A one-dimensional trapped atomic ion chain was used, which is the same as the system in which the first time crystal dynamics signal was observed five years ago. Interestingly, the multibody localized time crystal represents an inherent quantum Floquet phase, while the preheating time crystal can exist as a quantum phase or classical phase of matter.
However, many outstanding issues still exist. Is there any practical application of time crystals? Does dissipation help prolong the lifetime of time crystals? More generally, how and when do driven quantum systems reach equilibrium?
The results of this report show that spin defects in solids are a flexible platform for experimental research on these important open problems in statistical physics.
"Being able to isolate spins from the environment while still controlling their interactions provides a great opportunity to study how information is saved or lost. It will be very interesting to see what happens next," said Francisco Machado, a graduate student at the University of California, Berkeley.
Link:
[1] https://www.science.org/doi/10.1126/science.abk0603
[2] https://www.science.org/doi/10.1126/science.abg8102
