Quantum tomography for measuring experimentally the matrix elements of an arbitrary quantum operation

Phys Rev Lett. 2001 May 7;86(19):4195-8. doi: 10.1103/PhysRevLett.86.4195.

Abstract

Quantum operations describe any state change allowed in quantum mechanics, including the evolution of an open system or the state change due to a measurement. We present a general method based on quantum tomography for measuring experimentally the matrix elements of an arbitrary quantum operation. As input the method needs only a single entangled state. The feasibility of the technique for the electromagnetic field is shown, and the experimental setup is illustrated based on homodyne tomography of a twin beam.