Entanglement Protection And Quantum Acceleration Of Quantum Systems In Non-markovian Environments

Quantum mechanics has changed people’s understanding of the world,and its combination with informatics gives birth to quantum informatics,showing attractive application prospects,such as quantum computers,quantum secure communication and so on.Quantum entanglement plays an important role in these applications.However,the real physical system will inevitably interact with the external environment to destroy quantum entanglement,which hinders the realization of the broad application prospects of quantum information.Since the principle of quantum mechanics sets a lower limit for the dynamic evolution time of the quantum system,the field of quantum information also pays attention to the shortest time required for the quantum system to evolve from the initial state to the target state,namely the quantum speed limit time,which reflects the maximum evolution speed of the quantum system.Therefore,it is of great theoretical and practical significance to study the protection of quantum entanglement and the accelerated evolution of quantum systems in open systems.This article mainly studies the following contents:1.The entanglement between two qubits in the independent double Lorentzian spectrum environment protected by Zeno effect is studied.Pseudomode theory is used to solve the probability amplitude equation when the initial state of the system is the maximally entangled state,the entanglement of the system is measured and witnessed by the concurrence and entropy uncertainty relation,respectively.It is found that there is no Zeno effect,the non-Markovian property of the environment can protect the quantum entanglement and prolong the entanglement witness time.In the presence of Zeno effect,the protective effect of entanglement is significantly enhanced,and the entanglement witness time is significantly prolonged.2.The influence of the Ohmic spectrum on the non-Markovianity and quantum speed limit time of the two-level atom in the dissipative cavity are discussed in detail,and the non-Markovianity described by the survival probability of the atom in the excited state and the decoherence rate in the master equation is obtained.The results show that the atom-cavity coupling is the main physical reason for the transformation of the atomic system dynamics from Markovian to non-Markovian,and also the main physical reason for the acceleration of the evolution of atomic system;in addition,this transition from a Markovian state to a non-Markovian state only depends on the ohmic parameter.