AI-Driven Pulses Tame Quantum Systems

It is easy to control the trajectory of a basketball: it is enough to apply a mechanical force coupled with a human skill. But controlling the movement of quantum systems such as atoms and electrons is much more difficult, because these tiny bits of matter often fall prey to disturbances that throw them off course in unpredictable ways. Motion within the system degrades – a process called damping – and noise from environmental effects such as temperature also disrupts its path.

One way to counter damping and noise is to apply stabilizing pulses of light or voltage of fluctuating intensity to the quantum system. Researchers from the Okinawa Institute of Science and Technology (OIST) in Japan have shown that they can use artificial intelligence to discover these pulses in an optimized way to appropriately cool a micromechanical object to its quantum state and to control its movement. Their research was published in November 2022 in Physical examination research.

Micromechanical objects, large in size compared to an atom or an electron, behave conventionally when they are maintained at high temperature, even at room temperature. However, if these mechanical modes can be cooled down to their lowest energy state, which physicists call the ground state, quantum behavior could be achieved in such systems. These types of mechanical modes can then be used as ultra-sensitive sensors for force, displacement, gravitational acceleration, etc. as well as for quantum processing and computing.

“Technologies built from quantum systems offer immense possibilities,” said Dr Bijita Sarma, lead author of the paper and a postdoctoral researcher at the OIST Quantum Machines Unit in Professor Jason Twamley’s lab. “But to benefit from their promise of ultra-precise sensor design, high-speed quantum information processing, and quantum computing, we must learn to design ways to achieve rapid cooling and control of these systems.”

The machine learning-based method she and her colleagues devised shows how artificial controllers can be used to discover non-intuitive smart pulse sequences that can cool a mechanical object from high to ultra-cold temperatures faster than other standard methods. These control pulses are self-discovered by the machine learning agent. The work presents the usefulness of machine artificial intelligence in the development of quantum technologies.

Quantum computing has the potential to revolutionize the world by enabling high computing speeds and cryptographic reformatting techniques. This is why many research institutes and large technology companies such as Google and IBM invest a lot of resources in the development of such technologies. But to enable this, researchers must achieve complete control of the operation of such very high-speed quantum systems, so that the effects of noise and damping can be eliminated.

“In order to stabilize a quantum system, the control pulses must be fast – and our artificial intelligence controllers have shown promise in achieving such [a] feat,” Dr. Sarma said. “Thus, our proposed method of quantum control using an AI controller could be a breakthrough in the field of high-speed quantum computing, and it could be a first step to realize quantum machines that are self-driving, similar to self-driving cars. We hope that such methods will attract many quantum researchers for future technological developments.”