Entangled States of More Than 40 Atoms in an Optical Fiber Cavity

TLDR

Multiparticle entanglement is essential for quantum simulations, computing, and metrology, yet scalable methods that preserve single‑qubit resolution are scarce. The study develops a scalable approach using atom chips and fiber‑optical cavities to generate symmetric entangled states via nondestructive collective measurement and conditional evolution, and to perform their tomography. The method employs atom chips and fiber‑optical cavities, using nondestructive collective measurement and conditional evolution to create and tomographically analyze symmetric entangled states. The authors created and analyzed symmetric entangled states of up to 41 atoms, experimentally confirming multiparticle entanglement, and demonstrated that the method is atom‑number independent and generalizable to other entangled states and platforms such as circuit QED.

Abstract

Multiparticle entanglement enables quantum simulations, quantum computing, and quantum-enhanced metrology. Yet, there are few methods to produce and measure such entanglement while maintaining single-qubit resolution as the number of qubits is scaled up. Using atom chips and fiber-optical cavities, we have developed a method based on nondestructive collective measurement and conditional evolution to create symmetric entangled states and perform their tomography. We demonstrate creation and analysis of entangled states with mean atom numbers up to 41 and experimentally prove multiparticle entanglement. Our method is independent of atom number and should allow generalization to other entangled states and other physical implementations, including circuit quantum electrodynamics.