Quantum sensing with unlimited optical bandwidth

Zoom Link: https://us02web.zoom.us/j/89236785442

Quantum sensing with unlimited optical bandwidth

Avi Pe’er, Physics department and QUEST center for quantum technology, Bar Ilan University, Ramat Gan 52900 ISRAEL

Squeezed light is a major resource for quantum interferometric sensing below the shot-noise limit. However, standard squeezed interferometry methods suffer from two severe limitations: First, the detection bandwidth of squeezing-enhanced interferometry is inherently narrow because of the slow response (MHz to GHz) of photodetectors, which prevents efficient utilization of the optical bandwidth (tens of THz and more) for quantum applications; and second, current quantum sensing requires near ideal photo-detectors with unity efficiency, prohibiting applications, where ideal detection is not available. To overcome these limitations and harvest the orders-of-magnitude enhancement of the sensing throughput, a paradigm shift is required in terms of broadband quantum sources, detection schemes, and interferometric design.
I will present a set of new methods for sub-shot-noise sensing, based on nonlinear interferometry, which overcome these limitations. By placing the phase object in question between two parametric amplifiers in series, the first amplifier generates broadband squeezed light to interrogate the object and the second amplifier acts as an ideal broadband quantum detector to measure the object’s response. This technique is robust to detection inefficiency and provides an unprecedented optical bandwidth for quantum measurement, exceeding the possibilities of photodetectors by several orders of magnitude.
I will discuss in detail two specific examples of ultra broadband parametric-homodyne measurement [1] and of squeezing-enhanced Raman spectroscopy [2].

References:
[1] Y. Shaked, Y. Michael, R. Vered, L. Bello, M. Rosenbluh and A. Pe’er, “Lifting the Bandwidth Limit of Optical Homodyne Measurement”, Nature Communications 9, 609 (2018).
[2] Y. Michael, L. Bello, M. Rosenbluh, and A. Pe'er, “Squeezing-enhanced Raman Spectroscopy”,  npj Quantum Information 5, 81 (2019).

[3] L. Bello, Y. Michael, M. Rosenbluh, E. Cohen and A. Pe’er, “Broadband complex two-mode quadratures for quantum optics”, Optics Express 29, 41282 (2021)