Characterization of depolarizing channels using two-photon interference
G. C. Amaral (Kavli institute of nanoscience Delft, TU Delft - QID/Tittel Lab, TU Delft - QuTech Advanced Research Centre)
G. P. Temporão (Pontifical Catholic University of Rio de Janeiro)
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Abstract
Depolarization is one of the most important sources of error in a quantum communication link that can be introduced by the quantum channel. Even though standard quantum process tomography can, in theory, be applied to characterize this effect, in most real-world implementations depolarization cannot be distinguished from time-varying unitary transformations, especially when the timescales are much shorter than the detectors response time. In this paper, we introduce a method for distinguishing true depolarization from fast polarization rotations by employing Hong–Ou–Mandel interference. It is shown that the results are independent of the timing resolutions of the photodetectors.