Search results for "ELECTRONICS"
showing 10 items of 4340 documents
Comparative investigation of the freezing phenomena for quantum correlations under nondissipative decoherence
2013
We show that the phenomenon of frozen discord, exhibited by specific classes of two-qubit states under local nondissipative decoherent evolutions, is a common feature of all known bona fide measures of general quantum correlations. All those measures, despite inducing typically inequivalent orderings on the set of nonclassically correlated states, return a constant value in the considered settings. Every communication protocol which relies on quantum correlations as resource will run with a performance completely unaffected by noise in the specified dynamical conditions. We provide a geometric interpretation of this
Steady-state generation of negative-Wigner-function light using feedback
2016
We propose a method of producing steady-state coherent light with negative Wigner functions in nonlinear media combined with feedback control. While the nonlinearities are essential to produce the Wigner negativities, this alone is insufficient to stabilize steady-state light with negativities. Using feedback control to control the phase in the cavity, we find that this produces significant total negativities for reasonable experimental parameters. The negative Wigner function is produced continuously and does not appear to be restricted to low-amplitude light. The technique is applicable to systems such as exciton-polaritons, where strong natural nonlinearities are present.
Controlled transport of stored light
2020
Controlled manipulation, storage, and retrieval of quantum information is essential for quantum communication and computing. Quantum memories for light, realized with cold atomic samples as the storage medium, are prominent for their high storage efficiencies and lifetime. We demonstrate the controlled transport of stored light over 1.2 mm in such a storage system and show that the transport process and its dynamics only have a minor effect on the coherence of the storage. Extending the presented concept to longer transport distances and augmenting the number of storage sections will allow for the development of novel quantum devices such as optical racetrack memories or optical quantum reg…
Fast and robust population transfer in two-level quantum systems with dephasing noise and/or systematic frequency errors
2013
We design, by invariant-based inverse engineering, driving fields that invert the population of a two-level atom in a given time, robustly with respect to dephasing noise and/or systematic frequency shifts. Without imposing constraints, optimal protocols are insensitive to the perturbations but need an infinite energy. For a constrained value of the Rabi frequency, a flat $\pi$ pulse is the least sensitive protocol to phase noise but not to systematic frequency shifts, for which we describe and optimize a family of protocols.
NON-MARKOVIAN DYNAMICS OF CAVITY LOSSES
2008
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.
Stochastic collision model approach to transport phenomena in quantum networks
2021
Abstract Noise-assisted transport phenomena highlight the nontrivial interplay between environmental effects and quantum coherence in achieving maximal efficiency. Due to the complexity of biochemical systems and their environments, effective open quantum system models capable of providing physical insights on the presence and role of quantum effects are highly needed. In this paper, we introduce a new approach that combines an effective quantum microscopic description with a classical stochastic one. Our stochastic collision model (SCM) describes both Markovian and non-Markovian dynamics without relying on the weak coupling assumption. We investigate the consequences of spatial and tempora…
Coupling of a dipolar emitter into one-dimensional surface plasmon.
2013
Quantum plasmonics relies on a new paradigm for light-matter interaction. It benefits from strong confinement of surface plasmon polaritons (SPP) that ensures efficient coupling at a deep subwavelength scale, instead of working with a long lifetime cavity polariton that increases the duration of interaction. The large bandwidth and the strong confinement of one dimensional SPP enable controlled manipulation of a nearby quantum emitter. This paves the way to ultrafast nanooptical devices. However, the large SPP bandwidth originates from strong losses so that a clear understanding of the coupling process is needed. In this report, we investigate in details the coupling between a single emitte…
A proposed quantum mechanics mechanism for (e−, h+) charges separation applied to photosynthesis and energy production efficiency improovement
2009
Based on concepts in semiconductor band gap engineering (the staggered one), a qualitative model is proposed for the first step mechanism in artificial catalysis and natural systems such as photosynthesis in green leaves.
Coherent control of stimulated emission process inside one-dimensional photonic crystals
2005
The control of the stimulated emission processes in a 1D PC is discussed. A non-canonical quantization is adopted (QNM). The decay rate of the stimulated emission depends on the cavity and phase-difference of the pumps.
Heat flux and quantum correlations in dissipative cascaded systems
2015
We study the dynamics of heat flux in the thermalization process of a pair of identical quantum systems that interact dissipatively with a reservoir in a cascaded fashion. Despite that the open dynamics of the bipartite system $S$ is globally Lindbladian, one of the subsystems ``sees'' the reservoir in a state modified by the interaction with the other subsystem and hence it undergoes a non-Markovian dynamics. As a consequence, the heat flow exhibits a nonexponential time behavior which can greatly deviate from the case where each party is independently coupled to the reservoir. We investigate both thermal and correlated initial states of $S$ and show that the presence of correlations at th…