[QIP-Sem] QIP seminar, Mon 11/30, 4:00, 36-428, Pirandola, Stefano

[Peter Shor]

MIT Quantum Information Processing seminar
Monday 11/30 at 4:00 in 36-428
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 Pirandola,Stefano (MIT/University of York)

 Gaussian Channel Discrimination

Abstract:

 The optimal discrimination of quantum states is a central problem in quantum information theory. A problem of equal importance, but more difficult to solve, is the optimal discrimination between different quantum channels. In this seminar we analyze these general problems and we specialize them to the scenario of bosonic systems. First we consider the optimal discrimination between two arbitrary Gaussian states, showing how we can estimate the corresponding error probability via the quantum Chernoff bound. Then, we consider the case of two Gaussian channels. Here we provide a lowerbound for the minimum error probability which affects the "classical discrimination" of these channels, i.e., their optimal discrimination assuming "classical states" as input (defined as states with positive P-representation). Exploiting this bound, we can find channel discrimination problems where the use of a "non-classical" input state (e.g., an entangled state) outperforms the use of any "clas
 sical" input state. This enhancement is shown in two paradigmic tasks: the sensing of low-reflectivity targets in bright thermal-noise baths (quantum illumination), and the readout of classical digital memories (quantum reading).

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