0508012v2

related topics
{photon, photons, single}
{measurement, state, measurements}
{time, wave, function}
{cos, sin, state}
{vol, operators, histories}
{phase, path, phys}
{states, state, optimal}
{let, theorem, proof}
{theory, mechanics, state}
{equation, function, exp}
{state, states, coherent}
{qubit, qubits, gate}
{operator, operators, space}
{state, phys, rev}
{force, casimir, field}

Quantum Bayesian methods and subsequent measurements

Filippo Neri

abstract: After a derivation of the quantum Bayes theorem, and a discussion of the reconstruction of the unknown state of identical spin systems by repeated measurements, the main part of this paper treats the problem of determining the unknown phase difference of two coherent sources by photon measurements. While the approach of this paper is based on computing correlations of actual measurements (photon detections), it is possible to derive indirectly a probability distribution for the phase difference. In this approach, the quantum phase is not an observable, but a parameter of an unknown quantum state. Photon measurements determine a probability distribution for the phase difference. The approach used in this paper takes into account both photon statistics and the finite efficiency of the detectors.

oai_identifier:
oai:arXiv.org:quant-ph/0508012
categories:
quant-ph
comments:
Expanded and corrected version. 13 pages, 1 figure
doi:
10.1103/PhysRevA.72.062306
arxiv_id:
quant-ph/0508012
journal_ref:
Phys.Rev.A 72, 062306 (2005)
report_no:
LA-UR-05-5519
created:
2005-08-01
updated:
2005-08-29

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