Single-Spin Addressing in an Atomic Mott Insulator

TL;DR

This paper demonstrates precise single-spin control in an optical lattice Mott insulator, enabling the creation of arbitrary spin patterns and observation of quantum dynamics at the single-atom level, advancing quantum simulation and information processing.

Contribution

The authors developed a method for addressing individual atoms in a Mott insulator with sub-diffraction resolution, allowing for arbitrary spin pattern creation and direct observation of quantum tunneling dynamics.

Findings

Single-atom spin flipping with sub-diffraction resolution.

Creation of arbitrary spin patterns in a 2D atomic array.

Observation of tunneling quantum dynamics of individual atoms.

Abstract

Ultracold atoms in optical lattices are a versatile tool to investigate fundamental properties of quantum many body systems. In particular, the high degree of control of experimental parameters has allowed the study of many interesting phenomena such as quantum phase transitions and quantum spin dynamics. Here we demonstrate how such control can be extended down to the most fundamental level of a single spin at a specific site of an optical lattice. Using a tightly focussed laser beam together with a microwave field, we were able to flip the spin of individual atoms in a Mott insulator with sub-diffraction-limited resolution, well below the lattice spacing. The Mott insulator provided us with a large two-dimensional array of perfectly arranged atoms, in which we created arbitrary spin patterns by sequentially addressing selected lattice sites after freezing out the atom distribution. We directly monitored the tunnelling quantum dynamics of single atoms in the lattice prepared along a single line and observed that our addressing scheme leaves the atoms in the motional ground state. Our results open the path to a wide range of novel applications from quantum dynamics of spin impurities, entropy transport, implementation of novel cooling schemes, and engineering of quantum many-body phases to quantum information processing.