Interferometric sensitivity and entanglement by scanning through quantum phase transitions in spinor Bose-Einstein condensates

TL;DR

This paper analyzes how quantum phase transitions in spinor Bose-Einstein condensates can generate entanglement with high interferometric sensitivity, revealing new regimes and optimal measurement strategies for enhanced quantum sensing.

Contribution

It uncovers a second entanglement regime with Heisenberg scaling and proposes optimal measurement protocols, advancing quantum metrology in spinor condensates.

Findings

Identification of a second entanglement regime with Heisenberg scaling

Optimal measurement strategies for maximizing sensitivity

Robustness of Fisher information against non-adiabaticity and noise

Abstract

Recent experiments have demonstrated the generation of entanglement by quasi-adiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identify optimal unitary transformations and an experimentally feasible optimal measurement prescription that maximize the interferometric sensitivity. We further ascertain that the Fisher information is robust with respect to non-adiabaticity and measurement noise. Finally, we show that the quasi-adiabatic entanglement preparation schemes admit higher sensitivities than dynamical methods based on fast quenches.