Erlangen 2022 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 65: Quantum Information (Miscellaneous)

Q 65.3: Vortrag

Freitag, 18. März 2022, 11:00–11:15, Q-H12

Sensing with few photons: beating the Standard Quantum Limit in lossy SU(1,1) interferometers — •Matteo Santandrea, Kai Hong Luo, Michael Stefszky, Jan Sperling, Harald Herrmann, Benjamin Brecht, and Christine Silberhorn — Paderborn University, Department of Physics, Integrated Quantum Optics, Institute for Photonic Quantum Systems (PhoQS), Warburgerstr. 100, D-33098 Paderborn, Germany

SU(1,1) interferometers have been shown to be able to beat the Standard Quantum Limit (SQL), since their uncertainty in phase estimation scales as ∼ 1/⟨n⟩, in the limit of ⟨n⟩≫ 1, where ⟨n ⟩ indicates the mean photon number inside the interferometer. However, in recent years, these systems have been used more and more often in the low photon number regime (⟨n ⟩≪ 1) for spectroscopy and microscopy applications, where the scaling properties are not considered. In this regime, it is not obvious whether they can beat the SQL or in which cases - in particular when losses inside and outside the interferometer are considered.

In this contribution, we investigate lossy SU(1,1) interferometers in the low photon number regime. We show that concidence measurement can drastically help in beating the SQL and that it is still possible to beat the SQL even in the presence of moderate losses inside the setup.

The results of this work are fundamental in understanding the behaviour of SU(1,1) interferometers in the low photon number regime and provides the foundations for improved low-photon-number interferometric schemes.