New Discovery Allows Quantum Systems To Stay Operational 10,000 Times Longer

Researchers from the Pritzker School of Molecular Engineering, University of Chicago announced the discovery of a simple modification that allows quantum systems to stay operational, or “coherent”, 10,000 times longer than before.

We all know that quantum mechanics holds a lot of potential and can give us a lot of new possibilities but to harness these, scientists need to find ways to keep quantum systems coherent for as long as possible.

Though current modification was tested on a specific class of quantum systems called solid-state qubits, researchers think that it would work on other quantum systems as well which can revolutionize Quantum communication, computers, and sensing.

“This breakthrough lays the groundwork for exciting new avenues of research in quantum science,” said study lead author David Awschalom, the Liew Family Professor in Molecular Engineering, senior scientist at Argonne National Laboratory and director of the Chicago Quantum Exchange. “The broad applicability of this discovery, coupled with a remarkably simple implementation, allows this robust coherence to impact many aspects of quantum engineering. It enables new research opportunities previously thought impractical.”

We all know that quantum laws are very different from our world and we can build things like virtually unhackable internet. But there are some fundamental challenges.

The Problem
The problem is quantum systems are that quantum states need an extremely quiet, stable space to operate, as they are easily disturbed by background noise coming from vibrations, temperature changes, or stray electromagnetic fields.

There are a few common approaches to solve this problem and to keep the quantum systems coherent:
1. Physically isolating the system from the noisy surroundings
2. Making all of the materials as pure as possible

But these common methods have problems with scalability and thus researchers at University of Chicago took a different approach.

“With this approach, we don’t try to eliminate noise in the surroundings; instead, we “trick” the system into thinking it doesn’t experience the noise,” said postdoctoral researcher Kevin Miao, the first author of the paper.

With the usual electromagnetic pulse, the team applied an additional continuous alternating magnetic field. By precisely tuning this field, the scientists could rapidly rotate the electron spins and allow the system to “tune out” the rest of the noise.

This modification made the system to stay coherent up to 22 milliseconds, four orders of magnitude higher than without the modification. The system is able to almost completely tune out some forms of temperature fluctuations, physical vibrations, and electromagnetic noise, all of which usually destroy quantum coherence.

A lot of quantum system candidates were not used because of this quantum coherence problem but now with this solution, all the candidates can be re-evaluated.

“The best part is, it’s incredibly easy to do,” Miao said. “The science behind it is intricate, but the logistics of adding an alternating magnetic field are very straightforward.”

Journal Reference:
K. C. Miao et al. Universal coherence protection in a solid-state qubit. Science, Aug. 13, 2020 DOI: 10.1126/science.abc5186