Abstract: Distributed quantum sensing is an exciting emerging research field aimed at harnessing quantum resources to achieve quantum-enhanced sensitivity in the estimation of single or multiple parameters, including temperature, electromagnetic and gravitational fields, distributed in a given quantum network. In particular, squeezing is a well established resource given its feasibility and robustness to decoherence with respect to entangled sources. However, distributed quantum sensing schemes with squeezed light often suffer from experimental challenges, such as limitations on the range of values of the unknown parameter to be measured, the structure of the optical network encoding it, the need to iteratively adapt such a network and the presence of photonic losses.
We show that multiphoton interference of squeezed photons with homodyne measurements can be used to achieve Heisenberg limited precision in the estimation of an unknown parameter of arbitrary value in an arbitrary linear network without the need of iteratively adapted networks [1]. We demonstrate that such a technique can even be exploited in the estimation of a function of an arbitrary number of unknown distributed parameters, whose functional expression can be tuned by using a simple auxiliary network [2].
Furthermore, we demonstrate the robustness to losses in the Heisenberg limited estimation of a linear superposition of unknown phases by using a single squeezed vacuum source and an anti-squeezing operation at a single interferometer output [3].
[1] G. Gramegna et al. New J. of Physics 23, 053002 (2021); G. Gramegna et al. Phys. Rev. Research 3, 013152 (2021); D. Triggiani, P. Facchi, and V. Tamma, Eur. Phys. J. Plus 137:125 (2022)
[2] D. Triggiani, P. Facchi, and V. Tamma, Phys. Rev. A 104, 062603 (2021)
[3] D. Gatto, P. Facchi and V. Tamma, Phys. Rev. A 105, 012607 (2022); D. Gatto, P. Facchi and V. Tamma, Phys. Rev. Research 1, 032024 (2019)