Study on Quantum Entanglement Between Mesoscopic Circuit and Environment at Coherent State

摘要

Taking into account the interaction between electrons and phonons,in the case without-rotating-waveapproximation,we study the entangling property between the mesoscopic circuit and environment at coherent state orequilibrimn state.The result indicates that,in long time limit t→∞,the averages of charge and current in the circuitonly depend on the average of the system at the initial state when the environment is initially at thermal equilibrium.However,when the environment is initially at coherent state,the average of charge and current in the circuit is determinedby the specific coherent state ensemble.Generally speaking,the entanglement between the circuit and environment willlead to the quantum state purity declining of the circuit,then the circuit emerges decoherent phenomenon,and so amixed state appears.Purity changes are related to the initial quantum state of environment and circuit.With thefurther evolution of time,coherence will be gradually restored,but cannot return to 1.