Describing a quantum channel by state tomography of a single probe stateChang-shui Yu and He-shan Song
School of Physics and Optoelectronic Technology, Dalian University of Technology - Dalian 116024, PRC
received 8 September 2008; accepted in final form 4 May 2009; published May 2009
published online 4 June 2009
A general law is presented for (composite) quantum systems which directly describes the time evolution of quantum states (with one or both components) through an arbitrary noisy quantum channel. It is shown that the time evolution of all quantum states through a quantum channel can be completely captured by the evolution of a single “probe state". Thus, in order to grasp the information of the final output states subject to a quantum channel, especially an unknown one, only quantum state tomography of a single probe state is required, which dramatically simplifies the practical operations in experiment.
03.65.Ud - Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.).
42.50.Dv - Quantum state engineering and measurements.
03.65.Ta - Foundations of quantum mechanics; measurement theory.
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