3 research outputs found
Comment on "Loss-error compensation in quantum-state measurements"
In the two papers [T. Kiss, U. Herzog, and U. Leonhardt, Phys. Rev. A 52,
2433 (1995); U. Herzog, Phys. Rev. A 53, 1245 (1996)] with titles similar to
the one given above, the authors assert that in some cases it is possible to
compensate a quantum efficiency in quantum-state measurements,
violating the lower bound 1/2 proved in a preceding paper [G. M. D'Ariano, U.
Leonhardt and H. Paul, Phys. Rev. A 52, R1801 (1995)]. Here we re-establish the
bound as unsurpassable for homodyning any quantum state, and show how the
proposed loss-compensation method would always fail in a real measurement
outside the allowed region.Comment: 3 pages, RevTeX, 2 figures included, to appear on Phys. Rev. A (April
1998