VACUUM RABI SPLITTING IN A COMPACT NEAR-CONCENTRIC CAVITY

Abstract

The exploration of strong atom–light interaction is essential for quantum computing nodes, where atoms require mediators to enhance their interaction with incoming photons. Optical cavities, governed by cavity quantum electrodynamics, serve this role by confining photons in a small mode volume. Near-concentric cavities, a less-explored configuration, offer a balance of small mode volume and significant optical access for atom manipulation, while operating with low finesse. However, they are sensitive to misalignment near the concentric regime.

This thesis presents a near-concentric optical cavity system addressing stability issues close to the concentric regime. The system features a compact tensegrity mirror support structure with an 11 mm cavity length, achieving a residual cavity length variation of δL_{C, rms} = 0.36(2)?Å at a critical distance of d = 1.06(5)?µm, while allowing control of all necessary degrees of freedom. With this stability, vacuum Rabi splitting is observed with trapped atoms. For 10 atoms, the atom–cavity coupling strength is g₁₀ = 2π × 25.4(4)?MHz, placing the system in the strong coupling regime with a cooperativity of C = 5.1(5).

This near-concentric cavity offers high optical access and stability, making it a promising alternative for cavity-QED experiments and quantum logic gates with low-finesse resonators.