2001/12/20 by H. M. Wiseman · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physreva.65.032111
published as PRA 65, 032111 (2002) · 6 pages, no figures. To be published in Phys. Rev. A
arxiv created 2001/12/20 · arxiv updated 2009/12/01
Weak values as introduced by Aharonov, Albert and Vaidman (AAV) are ensemble average values for the results of weak measurements. They are interesting when the ensemble is preselected on a particular initial state and postselected on a particular final measurement result. I show that weak values arise naturally in quantum optics, as weak measurements occur whenever an open system is monitored (as by a photodetector). I use quantum trajectory theory to derive a generalization of AAV's formula to include (a) mixed initial conditions, (b) nonunitary evolution, (c) a generalized (non-projective) final measurement, and (d) a non-back-action-evading weak measurement. I apply this theory to the recent Stony-Brook cavity QED experiment demonstrating wave-particle duality [G.T. Foster, L.A. Orozco, H.M. Castro-Beltran, and H.J. Carmichael, Phys. Rev. Lett. 85, 3149 (2000)]. I show that the ``fractional'' correlation function measured in that experiment can be recast as a weak value in a form as simple as that introduced by AAV.