Abstract: It is now well recognized that quantum physics can be used to build better sensors. Such sensors can be based on unitary systems [1,2] such as various types of interferometers or open systems based on lossy scattering and transmission channels [3,4]. The Fisher quantum information framework allows to obtain the best parameter estimates and to design experiments that can reach Cramer-Rao limits. I will emphasize not only the importance of quantum states used as probes, but also the importance of the quantum character of the measurement schemes. I will emphasize the particular importance of squeezed states of matter and light for sensing studies. I will illustrate the results with experiments on the quantized motion of trapped ions [1,2] and on the quantum advantage in absorption and scattering [3,4] using intensity squeezed light beams. Furthermore, I will demonstrate how parametric devices, which produce squeezed states, can be used to enhance cavity-mediated interactions.

References: [1] SC Burd et al., Quantum amplification of mechanical oscillator motion, Science 364, 1163 (2019). [2] G. S. Agarwal and L. Davidovich, Quantization of quantum-amplified metrology via Fisher information, Phys. 4, L 012014 (2022). [3] J. Wang, L. Davidovich, and G. S. Agarwal, Quantum sensing of open systems: Estimation of damping constants and temperature, Phys. 2, 033389 (2020). [4] F. Li, T. Li, M. O. Scully, and G. S. Agarwal, Quantum advantage with seeded squeezed light for absorption measurement, Phys. Applied 15, 044030 (2021).

Author Bio: Girish S Agarwal, Professor Emeritus at Texas A&M University; specializing in quantum optics and author of "Quantum Optics" published by Cambridge University Press. His work is widely followed with an h-index of 97 and over 36,000 citations. He has been recognized with numerous awards, including the Max-Born Prize of the Optical Society of America in 1988, the CHTownes Medal of the Optical Society of America (2022), the Physics Prize of the World Academy of Sciences (1994), the Humboldt Research Prize (1997) from Germany. He was elected a Fellow of the Royal Society UK in 2008 and is a member of many other academies and societies.
https://en.wikipedia.org/wiki/Girish_Saran_Agarwal

Website: https://iqti.iisc.ac.in/
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