A broadband squeezed light source for table-top interferometry

Bergamin, Fabio, Kuntimaddi, Nikitha, Patra, Abhinav, Montoya, Stephanie, Mehmet, Moritz, Dooley, Katherine ORCID: https://orcid.org/0000-0002-1636-0233, Grote, Hartmut and Vahlbruch, Henning 2025. A broadband squeezed light source for table-top interferometry. New Journal of Physics 27 (12) , 125005. 10.1088/1367-2630/ae2987

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Abstract

We report on the characterisation of one of two broadband squeezed light sources (SLSs) 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 SLS is based on a hemilithic OPA with a 43.6 mm round-trip optical length and a linewidth of 138(2) MHz, making it the broadest-linewidth device to date among those suitable for long-term integration with interferometers operating at a wavelength of 1064 nm.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	IOP Publishing
ISSN:	1367-2630
Date of First Compliant Deposit:	8 January 2026
Date of Acceptance:	8 December 2025
Last Modified:	08 Jan 2026 12:15
URI:	https://orca.cardiff.ac.uk/id/eprint/183572

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