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arXiv · 2311.14172

Metrological Advantages in Seeded and Lossy Nonlinear Interferometers

Jasper Kranias·Guillaume Thekkadath·Khabat Heshami·Aaron Z. Goldberg
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Abstract

The quantum Fisher information (QFI) bounds the sensitivity of a quantum measurement, heralding the conditions for quantum advantages when compared with classical strategies. Here, we calculate analytical expressions for the QFI of nonlinear interferometers under lossy conditions and with coherent-state seeding. We normalize the results based on the number of photons going through the sample that induces a phase shift on the incident quantum state, which eliminates some of the previously declared metrological advantages. We analyze the performance of nonlinear interferometers in a variety of geometries and robustness of the quantum advantage with respect to internal and external loss through direct comparison with a linear interferometer. We find the threshold on the internal loss at which the quantum advantage vanishes, specify when and how much coherent-state seeding optimally counters internal loss, and show that a sufficient amount of squeezing confers to the quantum advantages robustness against external loss and inefficient detection.

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Jasper Kranias, Guillaume Thekkadath, Khabat Heshami, Aaron Z. Goldberg. 2023-11-23. Metrological Advantages in Seeded and Lossy Nonlinear Interferometers. https://doi.org/10.22331/q-2025-02-04-1619

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