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Single‐photon quantum filtering with multiple measurements
Author(s) -
Dong Zhiyuan,
Zhang Guofeng,
Amini Nina H.
Publication year - 2018
Publication title -
international journal of adaptive control and signal processing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 66
eISSN - 1099-1115
pISSN - 0890-6327
DOI - 10.1002/acs.2859
Subject(s) - detector , photon , physics , quadrature (astronomy) , quantum , quantum mechanics , quantum channel , statistical physics , quantum information , optics
Summary The single‐photon quantum filtering problems have been investigated recently with applications in quantum computing. In practice, the detector responds with a quantum efficiency of less than unity since there exists some mode mismatch between the detector and the system and the single‐photon signal may be corrupted by quantum white noise. Consequently, quantum filters based on multiple measurements are designed in this paper to improve estimation performance. More specifically, the filtering equations for a 2‐level quantum system driven by a single‐photon input state and under multiple measurements are presented in this paper. Four scenarios, ie, (1) 2 diffusive measurements with Q‐P quadrature form, (2) 2 diffusive measurements with Q‐Q quadrature form, (3) diffusive plus Poissonian measurements, and (4) 2 Poissonian measurements, are considered. It is natural to compare the filtering results, ie, measuring a single channel or both channels, which one is better? By the simulation where we use a single photon to excite an atom, it seems that multiple measurements enable us to excite the atom with higher probability than only measuring a single channel. In addition, a measurement back‐action phenomenon is revealed by the simulation results.