Year: 2004
Type: article
Abstract: Ramsey interferometry allows the estimation of the phase φ of rotation of the pseudospin vector of an ensemble of two-state quantum systems. For φ small, the noise-to-signal ratio scales as the spin-squeezing parameter ξ, with ξ<1 possible for an entangled ensemble. However states with minimum ξ are not optimal for single-shot measurements of an arbitrary phase. We define a phase-squeezing parameter, ζ, which is an appropriate figure of merit for this case. We show that (unlike the states that minimize ξ) the states that minimize ζ can be created by evolving an unentangled state (coherent spin state) by the well known two-axis counter-twisting Hamiltonian. We analyse these and other states (for example the maximally entangled state, analogous to the optical ‘NOON’ state ) using several different properties, including ξ, ζ, the coefficients in the pseudo-angular momentum basis (in the three primary directions) and the angular Wigner function W (θ,ϕ). Finally, we discuss the experimental options for creating phase-squeezed states and doing single-shot phase estimation.
Authors: Joshua Combes, H M Wiseman
Institution: Griffith University
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: bronze
Funder: Queensland Government
OpenAlex ID: W1978342477