The problem of discriminating with minimum error between two mixed quantum states is reviewed, with emphasis on the detection operators necessary for performing the measurement. An analytical result is derived for the minimum probability of errors in deciding whether the state of a quantum system is either a given pure state or a uniform statistical mixture of any number of mutually orthogonal states. The result is applied to two-qubit states, and the minimum error probabilities achievable by collective and local measurements on the qubits are compared.
Journal of Optics B: Quantum and Semiclassical Optics
- Pub Date:
- March 2004
- minimum-error discriminationmixed statetwo-qubit state;
- Quantum Physics
- 6 pages, contribution to the 10th CEWQO, submitted to J. Opt. B