A Squeezed-Light Receiver for Torsion-Coupled Signal Channels

This paper designs an optical receiver whose readout noise is reduced below the ordinary shot-noise level by squeezed vacuum injection, and computes the benefit for a channel in which a torsion background modulates the phase of a probe beam. With 10 dB of squeezing the phase readout noise falls to 1.37e-09 rad per root hertz, an improvement factor of 3.16 over the unsqueezed value at the same optical power. The receiver cavity sets a detection bandwidth of 33.3 kHz. The trade between squeezing depth, optical loss and bandwidth is worked through quantitatively, and the loss budget at which squeezing stops helping is identified. All results are computed from the stated assumptions; the receiver has not been built or measured.