We propose a new generalised formalism for estimating the quantum phase uncertainty of pure and mixed continuous-variable quantum states and compare this with the phase uncertainty given by the quantum Fisher information. In order to preserve the Hermiticity of the operators, we use the Heisenberg and Schroedinger uncertainty relations to derive expressions for the phase uncertainty from generalised Susskind-Glogower operators. This formalism not only offers the possibility of directly measuring quantum phase uncertainties in a cavity-QED experiment but also gives a significant computational saving over the quantum Fisher information approach, which requires diagonalisation of the density matrix.
@article{arxiv.1401.5358,
title = {Experimentally-driven approach for measuring quantum phase uncertainty},
author = {Jaewoo Joo and Jacob A. Dunningham and Daniel K. L. Oi and Timothy P. Spiller},
journal= {arXiv preprint arXiv:1401.5358},
year = {2014}
}
Comments
We consider that this work is incomplete and have decided to withdraw the paper