Harnessing the Quantum Behavior of Spins on Surfaces

TL;DR

This paper reviews how the combination of STM and ESR enables coherent control of individual surface spins, opening pathways for quantum sensing, control, and simulation at the atomic scale.

Contribution

It synthesizes recent advances in controlling and reading out single spins on surfaces using STM-ESR, highlighting their potential for quantum nanodevices and materials.

Findings

Coherent control of individual surface spins demonstrated.

Applications in quantum sensing, control, and simulation discussed.

Atomically-precise fabrication enables quantum device development.

Abstract

The desire to control and measure individual quantum systems such as atoms and ions in a vacuum has led to significant scientific and engineering developments in the past decades that form the basis of today's quantum information science. Single atoms and molecules on surfaces, on the other hand, are heavily investigated by physicists, chemists, and material scientists in search of novel electronic and magnetic functionalities. These two paths crossed in 2015 when it was first clearly demonstrated that individual spins on a surface can be coherently controlled and read out in an all-electrical fashion. The enabling technique is a combination of scanning tunneling microscopy (STM) and electron spin resonance (ESR), which offers unprecedented coherent controllability at the Angstrom length scale. This review aims to illustrate the essential ingredients that allow the quantum operations of single spins on surfaces. Three domains of applications of surface spins, namely quantum sensing, quantum control, and quantum simulation, are discussed with physical principles explained and examples presented. Enabled by the atomically-precise fabrication capability of STM, single spins on surfaces might one day lead to the realization of quantum nanodevices and artificial quantum materials at the atomic scale.