Studies On Quantum Steering And Quantum Coherence In Open Systems

Quantum coherence,exhibiting the fundamental feature of quantum superposition,marks the difference of quantum physics from classical physics.As an important resource,quantum coherence has practical applications in many physical fields.In quantum information science,the realization of quantum operations closely depends on the maintenance and transformation of coherence.The decoherence resulting from the coulping between systems and environment is one of the huge obstacles to the realization of quantum information tasks.So it is significant to study the quantum coherence in open system.The treatment of the system-environment interaction often starts with a perturbation theory and involves various approximations,such as the Born approximation,the Markov approximation,and the rotating-wave approximation(RWA).However,these approximations have limitations,because each of them has its own application conditions.For instance,the approximate approaches can not exactly characterize the dynamical behaviors of system in strong coupling condition.As a consequence,it is a significative problem to break through the approximation methods and describe the system evolutions exactly in theoretical and experimental simulations.Based on these points,in this thesis we investigate the quantum coherence and correlation in quantum open systems.Moreover,in quantum coherence resource theory,people hope to extract coherent resource as much as possible from the limited coherent one.Therefore,we also study how to realize the process of coherence distillation experimentally.The contents of this thesis are as follows:1.Experimental simulation of a quantum channel without the RWA in linear optical system.We propose the dynamical mapping of a single qubit under the non-RWA channel,which is calculated by the hierarchy equation method.Furthermore,we experimentally simulate the non-RWA channel in a linear optical setup,and the experimental and theoretical results are in good agreement.Based on the experimental channel,the different dynamical evolutions of quantum temporal steering are measured.And the quantum non-Markovian of RWA channel and non-RWA channel via the experimental channel are also examined.2.Assisted distillation of quantum coherence in decoherence channels.We study the effect of decoherence on the extracting coherence via local quantum incoherent operations and classical communication.According to the hierarchy equation method,we calculate the evolution of two-qubit under local RWA channel and non-RWA channel.The maximal local coherence of target qubit can be achieved via the optimal measurements on the auxiliary qubit.Meanwhile,we analyse the different dynamical evolutions between optimal extractable coherence and quantum incoherent relative entropy.3.Experimental demonstration of one-shot coherence distillation.We design a type of incoherent operation with the linear optical system,which can be applied to accomplish the pure-to-pure state transformations and thus demonstrate the one-shot coherence distillation.The experimental results exhibit the relationship among distillable coherence,error rate and initial superposition coefficient.In addition,we also propose how to realize the one-shot coherence distillation in superconducting quantum electrodynamics(QED)system and analyze the feasibility under dissipation and dephasing.Different from the optical system,circuit QED system has great potential to achieve complex distillation operation on high-dimensional states.