Quantum Coherence And Its Interference In Open Systems

Quantum coherence originates from the superposition principle of state in quantum mechanics and is the basis of quantum interference.In recent years,the measure of quantum coherence has been studied extensively and deeply,and the meaning and application of quantum coherence have been explored.It is found that quantum coherence is a very important physical resource,and has important potential applications in quantum computing,quantum precision measurment,quantum thermodynamics,quantum biology,quantum information and other fields.This article studies quantum coherence mainly from the following two aspects:(1)The distribution and evolution of quantum coherence in open quantum systems.The evolution regular and distribution characteristics of quantum coherence of three qubit systems(including W state,GHZ state and partially entangled state)under amplitude-damped channel,phase-damped channel and random unitary channel are studied by using the recently proposed quantum coherence quantify method based on resource theory.It found that the W state has both global coherence and bipartite coherence during the evolution process,and its monogamy relationship is always zero during the evolution process;However,during the evolution process of the GHZ state,only has the global coherence,and its monogony is always positive;On the other hand,the partial entangled state has global coherence,bipartite coherence,and monomeric coherence coherence during the evolution process,and its monogamy relationship is always negative.(2)The phenomena of the quantum beats of coherence in open quantum systems.Under the action of environment,the coherence of open quantum system oscillates with time due to non-Markov effect.The phenomenon of a quantum beat occurs when two or more oscillations of different frequencies are coherently superimposed.We design two dynamic models(single qubit model and two qubit model).In the single qubit model,we have one qubit interacting with two spin environments,and in the two-qubit model,we let two non-interacting qubits interact with their respective local environment.Each environment causes oscillations to the open system.By adjusting the oscillation frequency,the two oscillations produce coherent superposition,and the quantum beat phenomenon is observed.We also give the conditions for the generation of the quantum beats of coherence.