An analytical approach for treating unitary quantum systems with initial mixed states

作者：El Oranyl Faisal A A^*

来源：Laser Physics, 2013, 23(2): 025205.

DOI：10.1088/1054-660X/23/2/025205

Mixed states are important in quantum optics since they frequently appear in decoherence problems. When one of the components of the system is initially prepared in a mixed state and the mathematical closed form of the evolution operator of the system is not available, one cannot deduce the density matrix. We present an analytical approach to accurately solve this problem. We exploit the fact that any mixed state can be expressed in terms of the phase state. The approach can be applied on the condition that Schrodinger's equation of the system is solvable for any arbitrary initial state. We verify the validity of the approach for two examples, namely, the Jaynes-Cummings model and the two-qubit problem. Our results are in good agreement with the available results in the literature. This approach opens new perspectives for treating complicated systems and may impact other applications in quantum theory.

• 出版日期2013-2