Search results for "quant-ph"
showing 10 items of 1378 documents
Robust creation of atomic W state in a cavity by adiabatic passage
2009
We propose two robust schemes to generate controllable (deterministic) atomic W-states of three three-level atoms interacting with an optical cavity and a laser beam. Losses due to atomic spontaneous emissions and to cavity decay are efficiently suppressed by employing adiabatic passage technique and appropriately designed atom-field couplings. In these schemes the three atoms traverse the cavity-mode and the laser beam and become entangled in the free space outside the cavity.
Quantum state transfer with ultracold atoms in optical lattices
2016
Ultracold atoms can be used to perform quantum simulations of a variety of condensed matter systems, including spin systems. These progresses point to the implementation of the manipulation of quantum states and to observe and exploit the effect of quantum correlations. A natural direction along this line is provided by the possibility to perform quantum state transfer (QST). After presenting a brief discussion of the simulation of quantum spin chains with ultracold gases and reminding the basic facts of QST, we discuss how to potentially use the tools of present-day ultracold technology to implement the QST between two regions of the atomic system (the sender and the receiver). The fidelit…
Simulating quantum-optical phenomena with cold atoms in optical lattices
2010
We propose a scheme involving cold atoms trapped in optical lattices to observe different phenomena traditionally linked to quantum-optical systems. The basic idea consists of connecting the trapped atomic state to a non-trapped state through a Raman scheme. The coupling between these two types of atoms (trapped and free) turns out to be similar to that describing light–matter interaction within the rotating-wave approximation, the role of matter and photons being played by the trapped and free atoms, respectively. We explain in particular how to observe phenomena arising from the collective spontaneous emission of atomic and harmonic oscillator samples, such as superradiance and directiona…
A concise review on pseudo-bosons, pseudo-fermions and their relatives
2017
We review some basic definitions and few facts recently established for $\D$-pseudo bosons and for pseudo-fermions. We also discuss an extended version of these latter, based on biorthogonal bases, which lives in a finite dimensional Hilbert space. Some examples are described in details.
(Regular) pseudo-bosons versus bosons
2012
We discuss in which sense the so-called {\em regular pseudo-bosons}, recently introduced by Trifonov and analyzed in some details by the author, are related to ordinary bosons. We repeat the same analysis also for {\em pseudo-bosons}, and we analyze the role played by certain intertwining operators, which may be bounded or not.
Fermi-type interaction in molecular and atomic Hamiltonians. Application to molecular systems and Bose-Einstein condensates.
2008
International audience; We present a simple prescription to build phenomenological Hamiltonians describing Fermi-type interactions and apply the developed formalism to two distinct physical systems. First, in a very simple way, we derive equations describing time dynamics of two coherently coupled Bose-Einstein condensates. Further, for bent XY2 molecules, we reproduce all the experimental data with an excellent precision.
Moдель демкова–кунике для ассоциации холодных атомов: режим слабого взаимодействия.
2009
International audience; We examine the nonlinear dynamics of molecule formation at coherent photo- and magneto-association of an atomic Bose–Einstein condensate when the external field configuration is defined by the quasi-linear level crossing Demkov–Kunike model, characterized by a bell-shaped pulse and finite variation of the detuning. We present an approach to construct an approximation describing the temporal dynamics of the molecule formation in the weak interaction regime and apply the developed method to the nonlinear Demkov–Kunike problem. The presented approximation, written as a scaled solution to the linear problem associated to the nonlinear one we treat, contains adjustable pa…
Landau-Zener Transition for Association of an Atomic Bose-Einstein Condensate With Inter-Particle Elastic Interactions Included
2008
International audience; We study strong coupling limit of the non-linear Landau-Zener transition at coherent photo- and magneto-association of cold atoms, focusing on the role of the elastic interspecies scatterings. Using an exact third-order nonlinear differential equation for the molecular state probability, we develop a nontrivial version of the strained parameter method which enables us to construct a highly accurate and simple analytic approximation describing time dynamics of the coupled atom-molecular system.
From atomic to molecular Bose-Einstein condensates: a physically realizable term-crossing model for cold atom association
2010
Using an exact third-order NL di®erential equation for the molecular state probability, we develop a variational approach which enables us to construct highly accurate analytic approximations describing time dynamics of the coupled atom-molecular system in each of the interaction regimes. We show that the approximation describing time evolution of the molecular state probability both in the weak interaction limit and in the large detuning regime of the strong interaction limit can be written as a sum of two distinct terms; the ¯rst one, being a solution to a limit ¯rst-order NL equation, e®ectively describes the process of the molecule formation while the second one, being a scaled solution…
Stationary states in quantum walk search
2016
When classically searching a database, having additional correct answers makes the search easier. For a discrete-time quantum walk searching a graph for a marked vertex, however, additional marked vertices can make the search harder by causing the system to approximately begin in a stationary state, so the system fails to evolve. In this paper, we completely characterize the stationary states, or 1-eigenvectors, of the quantum walk search operator for general graphs and configurations of marked vertices by decomposing their amplitudes into uniform and flip states. This infinitely expands the number of known stationary states and gives an optimization procedure to find the stationary state c…