Quantum process tomography of single-photon quantum channels with controllable decoherence

Abstract

We characterized unital quantum channels of single-photon polarization qubits. The channels are composed of two birefringent crystals and wave plates, where their decoherence properties are controlled. An experimental comparison of two different depolarizing configurations was made using a quantum process tomography procedure. The results are with a high fidelity to theoretical predictions. © 2012 The Royal Swedish Academy of Sciences.