Interfacing Atomic Spins with Photons for Quantum Metrology, Simulation and Computation

TL;DR

This paper explores how atom-light interactions in cavities can be used for quantum metrology, simulation, and computation, emphasizing nonlocal spin systems and the potential for engineering nonclassical states and many-body physics.

Contribution

It provides a comprehensive overview of atom-light coupling mechanisms, introduces collective spin models, and discusses applications in quantum metrology and simulation with a focus on high-cooperativity cavity QED.

Findings

Cavity interactions enable quantum non-demolition measurements.

Photon-mediated interactions facilitate entanglement and nonclassical states.

High cooperativity is crucial for coherence in atom-light systems.

Abstract

These lecture notes discuss applications of atom-light interactions in cavities to quantum metrology, simulation, and computation. A focus is on nonlocally interacting spin systems realized by coupling many atoms to a delocalized mode of light. We will build up from the fundamentals: understanding how a cavity enables light to coherently imprint information on atoms and atoms to imprint information on the light, enabling quantum non-demolition measurements that constitute a powerful means of engineering nonclassical states. By extension, letting the intracavity light act back on the atoms enables coherent photon-mediated interactions. I start by discussing collective spin models, emphasizing applications in entanglement-enhanced metrology, before proceeding to richer many-body physics enabled by incorporating spatiotemporal control or employing multiple cavity modes. I will highlight opportunities for leveraging these tools for quantum simulations inspired by problems in condensed matter and quantum gravity. Along the way, I provide a pedagogical introduction to criteria for strong atom-light coupling, illustrate how the corresponding figure of merit -- the cooperativity -- sets fundamental limits on the coherence of atom-light interactions, and discuss prospects for harnessing high-cooperativity cavity QED in quantum simulation and computation.