2006/11/30 by Stefano Olivares, Matteo G. A. Paris, Matteo G A Paris
Computer Science · Engineering · Physics and Astronomy · #Direct-conversion receiver #Gaussian #Homodyne detection #Optical Network Technologies #Quantum Information and Cryptography #Quantum optics and atomic interactions #Scheme (mathematics) #Set (abstract data type) #State (computer science) #quant-ph
paper · pdf · doi:10.1088/1751-8113/40/28/s05
published as J. Phys. A 40, 7945 (2007) · 10 pages, 6 figures; published version
openalex publication_date 2007/06/27 · arxiv created 2007/07/04 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze in details a conditional measurement scheme based on linear optical components, feed-forward loop and homodyne detection. The scheme may be used to achieve two different tasks. On the one hand it allows the extraction of information with minimum disturbance about a set of coherent states. On the other hand, it represents a nondemolitive measurement scheme for the annihilation operator, i.e. an indirect measurement of the Q-function. We investigate the information/disturbance trade-off for state inference and introduce the estimation/distortion trade-off to assess estimation of the Q-function. For coherent states chosen from a Gaussian set we evaluate both information/disturbance and estimation/distortion trade-offs and found that non universal protocols may be optimized in order to achieve better performances than universal ones. For Fock number states we prove that universal protocols do not exist and evaluate the estimation/distortion trade-off for a thermal distribution.