Joint Seminar on Quantum Information and Technologies
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until 2023/2024 Quantum Information Seminar | YouTube channel
2025-11-20 (Thursday)
room 0.06, Pasteura 5 at 11:15 
Piotr Grochowski (Palacky University Olomouc)Phase-insensitive force sensing
Quantum sensing with continuous-variable systems offers a versatile platform for reaching fundamental precision limits. In this work, we develop a general theoretical framework for phase-insensitive sensing with bosonic modes subject to displacements with random phase, applicable to both single-mode and multimode scenarios. We derive analytical bounds on the achievable precision in terms of first-order correlations and average excitations, revealing how non-Gaussian resources can maximize sensitivity while maintaining robustness to decoherence. This framework provides a unified perspective for understanding force and amplitude estimation in experimentally relevant, lossy, and phase-randomized environments.
Specializing to the single-mode case [1], we find that excitation-number–resolving measurements remain optimal and that N-spaced Fock states and number-squeezed Schrödinger cat states can approach the fundamental bound while mitigating decoherence. In the multimode, distributed setting [2], we show that first-order correlations enable a collective quantum advantage that scales linearly with total excitations, even without a shared phase reference. Multimode states with definite joint parity saturate this limit and can be probed efficiently via local parity measurements. Our results provide experimentally accessible strategies for enhancing phase-insensitive quantum sensing across mechanical, optical, microwave, and hybrid continuous-variable platforms.
[1] PTG, Radim Filip, arXiv:2505.20832, to appear in Phys. Rev. Lett.
[2] PTG, Radim Filip, in prep.
Specializing to the single-mode case [1], we find that excitation-number–resolving measurements remain optimal and that N-spaced Fock states and number-squeezed Schrödinger cat states can approach the fundamental bound while mitigating decoherence. In the multimode, distributed setting [2], we show that first-order correlations enable a collective quantum advantage that scales linearly with total excitations, even without a shared phase reference. Multimode states with definite joint parity saturate this limit and can be probed efficiently via local parity measurements. Our results provide experimentally accessible strategies for enhancing phase-insensitive quantum sensing across mechanical, optical, microwave, and hybrid continuous-variable platforms.
[1] PTG, Radim Filip, arXiv:2505.20832, to appear in Phys. Rev. Lett.
[2] PTG, Radim Filip, in prep.