12.6 dB squeezed light at 1550 nm from a bow-tie cavity for long-term high duty cycle operation

TL;DR

This paper reports the development of a highly stable, long-term operational bow-tie cavity for generating over 12.6 dB of squeezed light at 1550 nm, suitable for advanced quantum technologies.

Contribution

It introduces a robust, high-duty-cycle squeezed light source with long-term stability and automated locking, advancing quantum optics applications at 1550 nm.

Findings

Achieved over 10 dB squeezing with 96.6% duty cycle over 50 hours

Maximum squeezing level of 12.6 dB at 1550 nm

Stable operation without relocks for 12 hours in a different mode

Abstract

Squeezed states are an interesting class of quantum states that have numerous applications. This work presents the design, characterisation, and operation of a bow-tie optical parametric amplifier (OPA) for squeezed vacuum generation. We report the high duty cycle operation and long-term stability of the system that makes it suitable for post-selection based continuous-variable quantum information protocols, cluster-state quantum computing, quantum metrology, and potentially gravitational wave detectors. Over a 50 hour continuous operation, the measured squeezing levels were greater than 10 dB with a duty cycle of 96.6%. Alternatively, in a different mode of operation, the squeezer can also operate 10 dB below the quantum noise limit over a 12 hour period with no relocks, with an average squeezing of 11.9 dB. We also measured a maximum squeezing level of 12.6 dB at 1550 nm. This represents one of the best reported squeezing results at 1550 nm to date for a bow-tie cavity. We discuss the design aspects of the experiment that contribute to the overall stability, reliability, and longevity of the OPA, along with the automated locking schemes and different modes of operation.