Abstract
Quantum metrology aims to yield higher measurement precisions via quantum techniques such as entanglement. It is of great importance for both fundamental sciences and practical technologies, from testing equivalence principle to designing high-precision atomic clocks. However, due to environment effects, highly entangled states become fragile and the achieved precisions may even be worse than the standard quantum limit (SQL). Here we present a high-precision measurement scheme via spin cat states (a kind of non-Gaussian entangled states in superposition of two quasi-orthogonal spin coherent states) under dissipation. In comparison to maximally entangled states, spin cat states with modest entanglement are more robust against losses and their achievable precisions may still beat the SQL. Even if the detector is imperfect, the achieved precisions of the parity measurement are higher than the ones of the population measurement. Our scheme provides a realizable way to achieve high-precision measurements via dissipative quantum systems of Bose atoms.
Highlights
Quantum metrology aims to yield higher measurement precisions via quantum techniques such as entanglement
Entangled states are sensitive to decoherence and their entanglement properties may rapidly vanish in the signal accumulation
Through calculating the phase estimation precision for different input states with initial total atomic numbers up to 100, we find that the atomic spin cat states with modest entanglement are robust against atom losses and may still achieve high precision beyond the standard quantum limit (SQL)
Summary
Quantum metrology aims to yield higher measurement precisions via quantum techniques such as entanglement. We present a high-precision phase measurement scheme via quantum interferometry with atomic spin cat states under atom losses[21,27]. Through calculating the phase estimation precision for different input states with initial total atomic numbers up to 100, we find that the atomic spin cat states with modest entanglement are robust against atom losses and may still achieve high precision beyond the SQL.
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