QIQT23 | Prof. Goutam K Samanta - Quantum sensing using Hong Ou Mandel Interferometer

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Speaker:Prof. Goutam K Samanta - PRL, Ahmedabad

Abstract:Hong-Ou-Mandel (HOM) interference, the bunching of two indistinguishable photons on a balanced beam-splitter, has emerged as a promising tool for quantum sensing. The interference dip-width, thus the spectral bandwidth of interfering pair-photons, highly influences the resolution of HOM-based sensors. Typically, the photon-pairs bandwidth, generated through parametric down-conversion, is increased using bulky and expensive ultrafast lasers, limiting their use outside the lab. We show the generation of photon pairs with flexible spectral bandwidth even using single-frequency, continuous-wave diode laser enabling high-precision, real-time sensing. Using a 1-mm-long periodically-poled KTP crystal, we produced degenerate, high-brightness photon pairs with a high spectral bandwidth resulting in a narrow HOM-dip to measure a displacement of 60 nm and vibration amplitude of 205 nm at a frequency of 8 Hz. Finally, we used the HOM interferometer to measure the temperature-dependent refractive index of nonlinear crystals as part of real-time, precision-augmented, in-field quantum sensing applications. In the current talk, I will explain the basics and our recent results on HOM interferometer-based quantum sensing results in detail.