报告人：Girish S Agarwal  教授   

主持人：荆杰泰 教授   

时间：2022年10月31日（周一）上午10：00   

地点：光学大楼B325会议室   

ZOOM会议 ID：837 2031 5279，密码：123456  

参会链接：https://us06web.zoom.us/j/83720315279?pwd=Y2x3bkxYdndkVHpvSE1wMFFzVWg1Zz09   

报告人简介：

Girish S Agarwal, University Distinguished Professor at Texas A&M University; specializes in quantum optics and is the author of “Quantum Optics” published by the Cambridge University Press. His work is widely followed with an h index of 97 with more than 36000 citations. He has been recognized by a large number of awards, including the Max-Born Prize from the Optical Society of America in 1988, The C. H. Townes medal of the Optical Society of America (2022), the physics prize of the World Academy of Sciences (1994), the Humboldt Research Award (1997) of Germany. He was elected Fellow of the Royal Society UK in 2008 and is a fellow many other academies and societies.

报告内容简介：

Absorption and gain measurements are routinely used in science and engineering. For such measurements using laser beams, the sensitivity is theoretically limited by the shot noise due to the fundamental Poisson distribution of photon number in laser radiation. Here, we use bright squeezed light to demonstrate that direct absorption and gain measurements can be performed with sensitivity beyond the shot-noise limit. We report direct sub-shot-noise measurement of absorption and gain that require neither homodyne/lock-in nor logic coincidence detection schemes. Previously we reported [1] more than 1 dB quantum advantage [ 3 dB when corrected losses in optical paths] for the measurement sensitivity at faint absorption levels. We present our detailed results on definite quantum advantage of about 3dB in measurements of Brillouin gain. The figure below is a typical representation of our data on quantum advantage. We would present applications of this advantage to Brillouin imaging [2].

Fig. (a) The signal to noise ratio (SNR) in decibel as a function of pu mp power in dBm. The blue squares and red circles are measurements for the squeezed and coherent light respectively. The blue solid and red dotted lines are linear fits, which yield a 3.36 dB quantum advantage calculated from the fitting parameters. (b) A typical set of SBS measurements with a spectrum analyzer when pump power is 7.5 mW, corresponding to the lowest point in (a). Red curve is obtained with coherent light, blue curve is obtained with squeezed light, black curve is also obtained with squeezed light but with lasers locked away from the water SBS resonance.

[1] F. Li, T. Li, M. O. Scully, and G. S. Agarwal, Quantum Advantage with Seeded Squeezed Light for Absorption Measurement, Phys. Rev. Applied 15, 044030 (2021)

[2] T. Li, F. Li, X. Liu, V. Yakovlev and G. S. Agarwal, Quantum-enhanced stimulated Brillouin scattering spectroscopy and imaging, OPTICA 9, 959 (2022).