2025/08/12 by F. Bergamin, N. Kuntimaddi, Bergamin, Fabio +12
Computer Science · Engineering · Physics and Astronomy · #FOS: Physical sciences #Optical Network Technologies #Optics (physics.optics) #Pulsars and Gravitational Waves Research #Quantum Information and Cryptography #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2508.08857
openalex publication_date 2025/08/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report on the characterisation of one of two broadband squeezed light sources developed for the Quantum Enhanced Space-Time (QUEST) experiment, using balanced homodyne detection. QUEST consists of a pair of co-located, table-top, power-recycled Michelson interferometers designed to probe stationary space-time fluctuations. The interferometers are designed to be shot-noise limited in the frequency range from 1 to 200 MHz, and squeezed light will be employed with the goal to reduce the shot noise by 6 dB at frequencies inside the linewidth of the optical parametric amplifier (OPA). We directly observed up to 6.8 dB of squeezing and maintained at least 3 dB of squeezing across the full 100 MHz measurement bandwidth. After accounting for the dark noise contribution, the inferred squeezing level increased to 8.6 dB. Our squeezed light source is based on a hemilithic OPA with a 43.6 mm round-trip optical length and a linewidth of 138 MHz, making it the broadest-linewidth device to date among those suitable for long-term operation.