Ultrasensitive measurement with amplitude-squeezed light

Doudou Wang, Quansen Wang, Qiang Zhang +1 more

We propose an ultrasensitive displacement measurement scheme to overcome the standard quantum limit (SQL) in the unresolved sideband cavity optomechanical system with nonlinear optomechanical coupling and squeezed light injection. By introducing the optimized quantum correlation, which is enabled by suitable choices of the squeezing angle, squeezing level, power of the probe light, and measurement angle of homodyne detection, the off-resonant displacement sensitivity reaches 6 dB below the SQL in linear optomechanical coupling. In contrast, displacement sensitivities with a coherent probe plus variational readout and squeezed probe plus fixed measurement angle (phase quadrature) are 2.6 dB and 4.6 dB below the SQL, respectively. By combining linear and quadratic optomechanical coupling, we show that the displacement sensitivity can be further improved to 9.6 dB below the SQL. Our results have potential applications in gravitational-wave detectors, quantum metrology, and the search for dark matter.

Virginia D’Auria, A. Porzio, Salvatore Solimeno

Benjamin J. Lawrie, Raphael C. Pooser

We demonstrate sub-shot-noise microcantilever displacement sensitivity using simple differential measurements with multi-spatial-mode squeezed light, a result that may be critical for ultra-trace sensing and imaging applications.

Gerd Breitenbach, Stephan Schiller, J. Mlynek

Yongqing Li, Min Xiao

We describe recent experiments on generation and applications of amplitude-squeezed states of light from a semiconductor diode laser. Amplitude-squeezed light with intensity noise 2 dB below the standard shot- noise limit was observed from a diode laser with a weak optical feedback from an external grating. Applications of this amplitude-squeezed light as a local oscillator in heterodyne detection in Doppler velocity measurement and weak light-scattering measurement are discussed.

Jianming Huang