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Register a new userBasic mechanisms in the laser control of non-Markovian dynamics
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Referring to a Fano-type model qualitative analogy we develop a comprehensive basic mechanism for the laser control of the non-Markovian bath response in strongly coupled Open Quantum Systems (OQS). A converged Hierarchy Equations Of Motion (HEOM) is worked out to numerically solve the master equation of a spin-boson Hamiltonian to reach the reduced electronic density matrix of a heterojunction in the presence of strong THz laser pulses. Robust and efficient control is achieved increasing by a factor ?2 non-Markovianity measured by the time evolution of the volume of accessible states. The consequences of such fields on the central system populations and coherence are examined, putting the emphasis on the relation between the increase of non- Markovianity and the slowing down of decoherence processes.
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We investigate what a snapshot of a quantum evolution - a quantum channel reflecting open system dynamics - reveals about the underlying continuous time evolution. Remarkably, from such a snapshot, and without imposing additional assumptions, it can be decided whether or not a channel is consistent with a time (in)dependent Markovian evolution, for which we provide computable necessary and sufficient criteria. Based on these, a computable measure of `Markovianity is introduced. We discuss how the consistency with Markovian dynamics can be checked in quantum process tomography. The results also clarify the geometry of the set of quantum channels with respect to being solutions of time (in)dependent master equations.
We study the laser-driven Dicke model beyond the rotating-wave approximation. For weak coupling of the system to environmental degrees of freedom the dissipative dynamics of the emitter-cavity system is described by the Floquet master equation. Projection of the system evolution onto the emitter degrees of freedom results in non-Markovian behavior. We quantify the non-Markovianity of the resulting emitter dynamics and show that this quantity can be used as an indicator of the dissipative quantum phase transition occurring at high driving amplitudes.
We construct a large class of completely positive and trace preserving non-Markovian dynamical maps for an open quantum system. These maps arise from a piecewise dynamics characterized by a continuous time evolution interrupted by jumps, randomly distributed in time and described by a quantum channel. The state of the open system is shown to obey a closed evolution equation, given by a master equation with a memory kernel and a inhomogeneous term. The non-Markovianity of the obtained dynamics is explicitly assessed studying the behavior of the distinguishability of two different initial systems states with elapsing time.
We provide a microscopic derivation for the non-Markovian master equation for an atom-cavity system with cavity losses and show that they can induce population trapping in the atomic excited state, when the environment outside the cavity has a non-flat spectrum. Our results apply to hybrid solid state systems and can turn out to be helpful to find the most appropriate description of leakage in the recent developments of cavity quantum electrodynamics.
The study of open quantum systems is important for fundamental issues of quantum physics as well as for technological applications such as quantum information processing. The interaction of a quantum system with its environment is usually detrimental for the quantum properties of the system and leads to decoherence. However, sometimes a coherent partial exchange of information takes place between the system and the environment and the dynamics of the open system becomes non-Markovian. In this article we study discrete open quantum system dynamics where single evolution step consist of local unitary transformation on the open system followed by a coupling unitary between the system and the environment. We implement experimentally a local control protocol for controlling the transition from Markovian to non-Markovian dynamics.
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