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arXiv:1902.04288 · Applied Physics Letters

Twin-beam-enhanced displacement measurement of a membrane in a cavity

Xinrui Wei, Jiteng Sheng, Yuelong Wu, Wu-Ming Liu, Haibin Wu

Published Dec 16, 2019• 9 citations
arXivHTMLPDF

Abstract

We report an experimental demonstration of quantum-enhanced displacement measurement of a membrane in an optical cavity by using bright quantum correlated light to surpass the shot-noise limit (SNL). The optical cavity enhances the displacement signal and the twin beams suppress the noise background 3 dB below the SNL at an equivalent optical power. Thus, the signal-to-noise ratio is significantly improved by simultaneously using optical cavities and twin beams, and a sensitivity of 200 am/Hz is achieved. The frequency fluctuations of twin beams are analyzed and reduced by using optical twin cavities. These results provide a useful method for precision measurements as well as to control cavity optomechanical systems with nonclassical light.

DOI
10.1063/1.5129547

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The optical shot-noise limit of a laser beam represents the classical limit in precision and signal to noise ratio achievable in optical sensors and imaging systems. It is known that quantum states of light, such as squeezed light and quantum correlated twin beams can be used to enhance precision and signal to noise ratio to beyond this limit. This promises optical sensors with fundamentally superior performance to the state of the art. While quantum-enhanced signal to noise ratio has been demonstrated with macroscopic powers of squeezed probe beam, demonstrations of quantum enhanced precision have remained at extremely low powers of light (femto-Watts). Here we will give examples where increasing SNR with quantum light is not sufficient to increase precision and we will review proof of principle experiments that have demonstrated sub shot noise precision, including for absorption spectroscopy and imaging. We will also report our efforts to achieve this sub-shot-noise precision performance for transmission measurement with ~0.1mW of average probe power, equating to ~10W peak power in a pulsed experiment. Time permitting, we will discuss how integrated optics and integrated electronics enables 10s GHz bandwidth in the detection of squeezed light, for integrated quantum sensor technology.
Measurement slight amounts of absorption of light with accuracy beyond the standard quantum limit has been experimentally demonstrated. The quantum-correlated twin beams used in the measurement were generated from a nondegenerate optical parametric oscillator including an alpha-cut KTiOPO(4) crystal pumped by an intracavity frequency-doubled Nd:YAG laser. The noise in the intensity difference between the twin beams was reduced by 88% below the standard quantum limit (SQL). The signal-to-noise ratio was improved by 7 dB with respect to the SQL of the total light employed in the experiment and by 4 dB with respect to that of the signal light.
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