Quantum Measurement And Quantum Correlation Of Cavity Field Quantum Dynamic Systems

In quantum theory,the quantum Zeno effect plays an important role in dealing with the quantum information.In this paper,chapter one firstly analyzes the background and the current development situation of the quantum entropy squeezing,quantum Zeno effect in the atom-field system.In the chapter two,we study at different time intervals measured how the quantum measurement impact the conversion probability between neutron and antineutron,which leads to the quantum Zeno effect.In the chapter three,we explore the quantum Zeno effect in an open quantum system under indirect measurements.We consider the quantum dynamics of a two-level system interacting with a squeezed environment.It is shown that the Zeno effect induced by indirect measurements is not observable in an open system.That is,the evolution of the system is independent of the monitoring.Our results suggest that,based on indirect measurements,an open quantum system should be probed as rarely as possible to yield the optimal estimation of the quantity measured.In the chapter four,we investigates the entropy squeezing of a qubit(two-level atom)interacting with the cavity field in the Schrodinger cat states.The effects of the Schrodinger cat states of the field on the squeezing are examined.Our results suggest that entropy squeezing is not sensitive to the superposition features of two coherent states of the Schrodinger cat states.Furthermore,it is found that entropy squeezing occurs as the qubit initially close to its maximally coherent state,and the qubit initially in the maximally coherent state can generate optimal squeezing.This also demonstrates that the atomic coherence has a remarkable effect on the atomic squeezing.On the other hand,we also show how the entropy squeezing is related to the intensity of the initial field.