Identification And Control Of Environment In Open Quantum Systems And Its Application

Quantum theory is a school of science that studies the nature of microscopic particles.Since its beginning in early 1900s,it has revolutionized our view of the universe,and brought about the information age as the theoretical foundation of semiconductor industry.The next holy grail for quantum scientist is to realize a quantum computer with sufficient scale to rival,for certain tasks,its top classical counterpart.To such end,a deeper understanding of various quantum systems,especially open quantum systems is required.To specify,it includes not only the knowledge of the environment and its effects,but also the means to engineer the open system dynamics through manipulating the environment.This thesis focuses on the identification and control of the environment.Special features in the dissipation,absorption and transport dynamics of open systems are explored,and their applications discussed.In the dissipation of a Non-Markovian single-mode system,a simpler formalism is given to the amplitude dynamics of the system,which enables us to obtain the spectral density of the environment from the system dynamics.Then,for a general network of bosonic modes under certain conditions,engineering of the final time system excitation is realized via the manipulation of the input photon from the environment.Also,in the transport dynamics of tight-binding systems,the influence of an environment is found to affect the form of its current observable.These findings deepens our understanding of open systems.This thesis consists of 6 chapters,which are organized as follows:In Chapter 1,the background of our work is outlined,including the history of quantum theory and quantum information,the state of photonic orthogonal temporal mode technology,and the theoretical framework of open quantum systems.In Chapter 2,the basic theory of quantum mechanics is summarized,and several key points important to understanding the theories in this thesis is presented.Also,for tight-binding model,especially topological insulators,the approach to introduce electric field to translation invariant tight-binding systems is explained,as well as the idea of topological invariant.In Chapter 3,the identification of open quantum system is studied.By substituting arbitrary environment with a network of bosonic modes,a simple derivation of an alterna-tive formula to non-Markovian dynamics is presented,which enables the calculation of the spectral density as well as the system mode frequency from only the system dynamics.This reveals that the single mode dissipation dynamics has a one-to-one correspondence with the combination of the two.Should one be able to control the spectral density of the environ-ment,a precise control of the dissipation dynamics can be achieved.Then,this approach is applied to the recovery of all parameters from a 1 dimensional chain of bosonic modes with one end coupled to an environment.In Chapter 4,we continue to examine the manipulation of initial excitations in the en-vironment.which is based on a linear system consisting a network of bosonic modes.This scheme is based on a one-to-one correspondence between the system mode and the mode of incoming photons.A particular configuration of such a photonic temporal mode demulti-plexer is discussed in detail.Situations both with and without,time-dependent coupling are addressed.In Chapter 5,the relation between the instantaneous probability current and the instan-taneous quantum state of a tight-binding system subject to the influence of environment is explored.Within Markovian regime,a straightforward open system correction to the current operator is derived.Then,for both Markovian and non-Markovian systems the aforemen-tioned linear relation itself is found to be unaffected by site-local noise.In Chapter 6,we conclude our contributions,discuss the prospect of our work.and outline some possibilities for future work.