Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 56: Poster VII

Q 56.39: Poster

Thursday, March 14, 2024, 17:00–19:00, KG I Foyer

Optimal Ramsey interferometry with echo protocols based on one-axis twisting — •Maja Scharnagl¹, Timm Kielinski², and Klemens Hammerer² — ¹Institute for Theoretical Physics, Leibniz University Hannover, Appelstrasse 2, 30167 Hannover, Germany — ²Institute for Theoretical Physics and Institute for Gravitational Physics (Albert-Einstein-Institute), Leibniz University Hannover, Appelstrasse 2, 30167 Hannover, Germany

We study a variational class of generalized Ramsey protocols that include two one-axis twisting (OAT) operations, one performed before the phase imprint and the other after. In this framework, we optimize the axes of the signal imprint, the OAT interactions, and the direction of the final projective measurement. We distinguish between protocols that exhibit symmetric or antisymmetric dependencies of the spin projection signal on the measured phase. Our results show that the quantum Fisher information, which sets the limits on the sensitivity achievable with a given uniaxially twisted input state, can be saturated within our class of variational protocols for almost all initial twisting strengths. By incorporating numerous protocols previously documented in the literature, our approach creates a unified framework for Ramsey echo protocols with OAT states and measurements.

Keywords: Ramsey spectroscopy; one-axis twisting; spin squeezing; metrology