# Quantum interface for noble-gas spins based on spin-exchange collisions

## TL;DR

This paper demonstrates a quantum interface between noble-gas nuclear spins and alkali-metal atoms via spin-exchange collisions, enabling long coherence times and potential for room-temperature quantum memories and entanglement.

## Contribution

It introduces a theoretical framework showing how spin-exchange collisions create a controllable, reversible quantum interface without compromising noble-gas spins' coherence.

## Key findings

- Weak collisions enable entanglement and excitation exchange.
- The hybrid system can reach strong-coupling regime.
- Potential for hour-long quantum memories at room temperature.

## Abstract

An ensemble of noble-gas nuclear spins is a unique quantum system that could maintain coherence for many hours at room temperature and above, owing to exceptional isolation from the environment. This isolation, however, is a mixed blessing, limiting the ability of these ensembles to interface with other quantum systems coherently. Here we show that spin-exchange collisions with alkali-metal atoms render a quantum interface for noble-gas spins without impeding their long coherence times. We formulate the many-body theory of the hybrid system and reveal a collective mechanism that strongly couples the macroscopic quantum states of the two spin ensembles. Despite their stochastic and random nature, weak collisions enable entanglement and reversible exchange of nonclassical excitations in an efficient, controllable, and deterministic process. With recent experiments now entering the strong-coupling regime, this interface paves the way towards realizing hour-long quantum memories and entanglement at room-temperature.