Some remarks on the determination of quantum states by measurements

J. M. Jauch, Eugene Paul Wigner, Mutsuo M. Yanase

Stephen Mark Barnett, David Thomas Pegg, John Jeffers +2 more

Given the result of a measurement on the output of a quantum optical communication channel, we show how to calculate a retrodictive state at the input. This state can be used by the receiver to determine the probability that any one of a given set of states was selected by the transmitter. We establish the remarkably simple result that retrodicting the prepared input signal for an attenuating (amplifying) channel corresponds to predicting the measured output signal for an amplifying (attenuating) channel.

Dan Cristian Marinescu, Gabriela M. Marinescu

K. L. Pregnell, David Thomas Pegg

Most methods for experimentally reconstructing the quantum state of light involve determining a quasiprobability distribution such as the Wigner function. In this paper we present a scheme for measuring individual density matrix elements in the photon number state representation. Remarkably, the scheme is simple, involving two beam splitters and a reference field in a coherent state.

K. L. Pregnell, David Thomas Pegg

Most methods for experimentally reconstructing the quantum state of light involve determining a quasiprobability distribution such as the Wigner function. In this paper we present a scheme for measuring individual density matrix elements in the photon number state representation. Remarkably, the scheme is simple, involving two beam splitters and a reference field in a coherent state.

J. M. Jauch, E. P. Wigner, Mutsuo M. Yanase