Phase-controlled improvement of photon lifetime in coupled superconducting cavities

TL;DR

This paper demonstrates that phase-controlled coupling between superconducting cavities can significantly enhance photon lifetime, with experimental results showing a twofold increase, impacting quantum information and sensing applications.

Contribution

It introduces a phase-tunable coupling method to improve photon lifetime in superconducting cavities, a novel approach not previously explored.

Findings

Photon lifetime can be doubled through phase control.

Phase and interference effects influence cavity lifetime.

Experimental validation with superconducting radio-frequency cavities.

Abstract

High-quality cavities are crucial for various fundamental physical studies and applications. Here we find that by coupling two cavities directly or via a phase-tunable coupling channel, the photon lifetime of the local field can exceed that of the bare cavities. The cavity photon lifetime is modified by the phases of the initial states and the phase accumulation on the coupling channel which affect the interference between cavities. In experiments, by coupling superconducting radio-frequency cavities via phase-tunable cables, we realize a factor of two improvement in the cavity photon lifetime. The results can bring rich revenue to quantum information science, sensing, and high-energy physics.