Nuclear spin squeezing in Helium-3 by continuous quantum nondemolition measurement

TL;DR

This paper introduces a method to achieve quantum control and spin squeezing of Helium-3 nuclear spins via continuous quantum nondemolition measurement using light, leveraging metastability exchange collisions.

Contribution

It presents a novel scheme for nuclear spin-light quantum nondemolition interaction in Helium-3, enabling measurement-based control and spin squeezing of nuclear spins.

Findings

Enables preparation of spin-squeezed states in Helium-3

Utilizes metastability exchange collisions for effective interaction

Leverages long coherence times for quantum applications

Abstract

We propose a technique to control the macroscopic collective nuclear spin of a Helium-3 vapor in the quantum regime using light. The scheme relies on metastability exchange collisions to mediate interactions between optically accessible metastable states and the ground-state nuclear spin, giving rise to an effective nuclear spin-light quantum nondemolition interaction of the Faraday form. Our technique enables measurement-based quantum control of nuclear spins, such as the preparation of spin-squeezed states. This, combined with the day-long coherence time of nuclear spin states in Helium-3, opens the possibility for a number of applications in quantum technology.