Enhancing the force sensitivity of a squeezed light optomechanical interferometer.

Application of frequency-dependent squeezed vacuum improves the force sensitivity of an optomechanical interferometer beyond the standard quantum limit by a factor of e-r, where r is the squeezing parameter. In this work, we show that the application of squeezed light along with quantum back-action nullifying meter in an optomechanical cavity with mechanical mirror in middle configuration can enhance the sensitivity beyond the standard quantum limit by a factor of e-reff, where reff = r + ln(4Δ/ζ)/2, for 0 < ζ/Δ < 1, with ζ as the optomechanical cavity decay rate and Δ as the detuning between cavity eigenfrequency and driving field. The technique described in this work is restricted to frequencies much smaller than the resonance frequency of the mechanical mirror. We further studied the sensitivity as a function of temperature, mechanical mirror reflectivity, and input laser power.

Quantum optomechanics without the radiation pressure force noise.

This Letter proposes a new method to eliminate the quantum radiation pressure force noise in optomechanics at frequencies much smaller than the resonance frequency of the optomechanical mirror. With no radiation pressure force noise, the shot noise and thermal noise together determine the total noise in the system. The force sensitivity of the optomechanical cavity is improved beyond standard quantum limit at frequencies much smaller than the resonance frequency of the mechanical oscillator. Finally, optimum optomechanical cavity design parameters for attaining the best sensitivity are discussed.

Overcoming standard quantum limit using a momentum measuring interferometer: publisher's note.

This publisher's note contains corrections to Opt. Lett.45, 1256 (2020)OPLEDP0146-959210.1364/OL.385092.

Overcoming standard quantum limit using a momentum measuring interferometer.

We show that back-action noise in the momentum measurement of a damped forced oscillator can be suppressed because of damping. Using this principle, we propose a back-action suppressed interferometer, in which the signal is a function of momentum of atoms in a harmonic trap. We show that the quantum noise limited sensitivity of this interferometer can overcome the standard quantum limit of force sensing, even at frequencies much smaller than the eigen frequency of the harmonic trap.