The Quantum Time Crystal

Google researchers create a time crystal in a quantum computer / E. Edwards/JQI. Google researchers create a time crystal in a quantum compu...

Google researchers create a time crystal in a quantum computer / E. Edwards/JQI.

Google researchers create a time crystal in a quantum computer Scientists at the search engine giant claim to have observed a genuine time crystal, using a quantum processor.

Once considered as a staple of science fiction, “time crystals’ continue to expand. While highly ordered crystalline structures occur in things like Salt, snowflakes, and diamonds — scientists have wondered if these atomic structure patterns can repeat in time, rather than in space. And this is where the concept of time crystals falls in.

First theorized in 2012 by MIT’s Noble Laureate Physicist Frank Wilczek, the concept initiated a contentious debate among scientific circles, on its feasibility. It wasn’t until 2017 when scientists were actually able to create a time crystal in a practical lab environment. Taking this discovery one step further, last year, an international team of researchers made a stunning breakthrough that these time crystals could interact with each other.

Although time crystals are hard to find, Google researchers now claim to have observed a genuine time crystal using a quantum processor. This, they believe, could lead to a “scalable approach” to study time crystals on current quantum processors. Unlike the traditional states of matter which are in thermal equilibrium, the time crystal is the first “out-of-equilibrium” phase — having order and perfect stability despite being in an excited and evolving state.

To observe the weird property of a time crystal in Google’s quantum processor, Sycamore, researchers applied a set of specific quantum operations to qubits spinning upwards and downwards in a closed system — done to change the state of qubits with repeated iterations, the final configuration was eerily similar to the original setup.

Applying these operations an even & odd number of times produced two setups — one which the system regularly went back-and-forth to, no matter how many operations were carried out. Scientists call this a break in the symmetry of time — which is why time crystals are called so. This is because the operation carried out to stimulate the system is always the same, and yet the same response comes to every other shake.

 Quantum computer processor / Quantum Magazine.

Simply put, the time-crystal state defies the second law of thermodynamics, which essentially defines the direction, that all natural events eventually take. Several other attempts have been made to observe the time crystals with varying levels of success, but none have been carried out at the scale at which Google attempted — using a chip with 20 qubits to serve as the time crystal.

Google’s experiment at the quantum level highlights the fact that it is possible to look at time crystals for longer, do detailed sets of measurements, vary the size of the system & so on. This demonstration of a quantum machine shows its capability of advancing new scientific discoveries. However, the challenge of decoherence still needs to be addressed, which causes a decay in the qubits’ quantum states — means that time crystals’ oscillations inevitably die out as the environment interferes with the system.

The team believes that effective isolation of the quantum processor could mitigate this problem. Although scientists are yet to find a practical use case of time crystals, the research proved that exciting times lie ahead for breakthrough scientific discoveries and quantum computers will have a huge role to play in them. Complete Research was published in the Preprint server arXiv.