Researchers develop new theory of electron spin to promote quantum devices

Researchers at Beijing Institute of Technology and California Institute of Technology have developed a new theory and numerical calculations to predict spin decoherence in materials with high accuracy. This addresses the issue of spin coherence: quantum states can be easily disrupted, which is a problem when attempting to use them in a device; the electron spins need to preserve their quantum state for as long as possible to avoid loss of information. Spin coherence is so delicate that even the tiny vibrations of the atoms that make up the device can alter the spin state irreversibly.

Marco Bernardi, professor of applied physics, physics and materials science, explains: "Existing theories of spin relaxation and decoherence focus on simple models and qualitative understanding. After years of systematic efforts, my group has developed computational tools to study quantitatively how electrons interact and move in materials. This new paper has taken our work a few steps further: we have adapted a theory of electrical transport to study spin, and discovered that this method can capture two main mechanisms governing spin decoherence in materials—spin scattering off atomic vibrations, and spin precession modified by atomic vibrations. This unified treatment allows us to study the behavior of the electron spin in a wide range of materials and devices essential for future quantum technologies".

He continued: "It is almost startling that in some cases we can predict spin decoherence times with an accuracy of a few percent of the measured values—down to a billionth of a second—and access microscopic details of spin motion beyond the reach of experiments. Ironically, our research tools—computers and quantum mechanics—can now be used to develop new computers that use quantum mechanics."

Posted: Nov 11,2022 by Roni Peleg