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ABSTRACT: We realize experimentally a cold atom system equivalent to the 3D Anderson
model of disordered solids where the anisotropy can be controlled by adjusting
an experimentally accessible parameter. This allows us to study experimentally
the disorder vs anisotropy phase diagram of the Anderson metal-insulator
transition. Numerical and experimental data compare very well with each other
and a theoretical analysis based on the self-consistent theory of localization
correctly discribes the observed behavior, illustrating the flexibility of cold
atom experiments for the study of transport phenomena in complex quantum
systems.
01/2013;
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ABSTRACT: We experimentally test the universality of the Anderson three dimensional metal-insulator transition, using a quasiperiodic atomic kicked rotor. Nine sets of parameters controlling the microscopic details have been tested. Our observation indicates that the transition is of second order, with a critical exponent independent of the microscopic details; the average value 1.63±0.05 agrees very well with the numerically predicted value ν=1.58.
Physical Review Letters 03/2012; 108(9):095701. · 7.37 Impact Factor
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ABSTRACT: Thanks to an all solid core photonic crystal fiber (PCF) used as a multicore fiber, we propose and experimentally demonstrate what is to our knowledge a new optical detection scheme for the spontaneous emission collection of cold atoms. A Magneto-Optical Trap (MOT) is placed in front of a polished PCF end-face. As they display a higher optical index than the surrounding cladding silica, the 108 rods (equivalent to a 108 pixels camera) of this PCF are light guiding and behave like an array of detectors. Both global and local properties of the trapped atoms are probed. A MOT lifetime is reported. We also take advantage of the multi-core geometry for a real time detection of the center-of-mass motion of the atomic cloud.
Optics Express 11/2011; 19(23):22936-41. · 3.59 Impact Factor
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ABSTRACT: We propose a method for arbitrary manipulations of a quantum wavepacket in an
optical lattice by a suitable modulation of the lattice amplitude. A
theoretical model allows to determine the modulation corresponding to a given
wavepacket motion, so that arbitrary atomic trajectories can be generated. The
method is immediately usable in state of the art experiments.
04/2011;
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ABSTRACT: Using a three-frequency one-dimensional kicked rotor experimentally realized with a cold atomic gas, we study the transport properties at the critical point of the metal-insulator Anderson transition. We accurately measure the time evolution of an initially localized wave packet and show that it displays at the critical point a scaling invariance characteristic of this second-order phase transition. The shape of the momentum distribution at the critical point is found to be in excellent agreement with the analytical form deduced from the self-consistent theory of localization.
Physical Review Letters 08/2010; 105(9):090601. · 7.37 Impact Factor
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ABSTRACT: We describe a method allowing transient suppression of decoherence effects on the atom-optics realization of the kicked rotor. The system is prepared in an initial state with a momentum distribution concentrated in an interval much sharper than the Brillouin zone; the measure of the momentum distribution is restricted to this interval of quasimomenta: As most of the atoms undergoing decoherence processes fall outside this detection range and thus are not detected, the measured signal is effectively decoherence-free. Comment: 5 pages, 4 figures, revtex 4, submitted to PRL
04/2010;
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ABSTRACT: We study the classical dynamics of a quasiperiodic kicked rotor, whose quantum counterpart is known to be an equivalent of the 3D Anderson model. Using this correspondence allowed for a recent experimental observation of the Anderson transition with atomic matter waves. In such a context, it is particularly important to assert the chaotic character of the classical dynamics of this system. We show here that it is a 3D anisotropic diffusion. Our simple analytical predictions for the associated diffusion tensor are found in good agreement with the results of numerical simulations. Comment: 8 pages, 7 figures, submitted to Jour. Mod. Opt.
03/2010;
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ABSTRACT: Using a cold atomic gas exposed to laser pulses -- a realization of the
chaotic quasiperiodic kicked rotor with three incommensurate frequencies -- we
study experimentally and theoretically the Anderson metal-insulator transition
in three dimensions. Sensitive measurements of the atomic wavefunction and the
use of finite-size scaling techniques make it possible to unambiguously
demonstrate the existence of a quantum phase transition and to measure its
critical exponents. By taking proper account of systematic corrections to
one-parameter scaling, we show the universality of the critical exponent
$\nu=1.59\pm0.01,$ which is found to be equal to the one previously computed
for the Anderson model.
07/2009;
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ABSTRACT: We realize experimentally an atom-optics quantum-chaotic system, the quasiperiodic kicked rotor, which is equivalent to a 3D disordered system that allows us to demonstrate the Anderson metal-insulator transition. Sensitive measurements of the atomic wave function and the use of finite-size scaling techniques make it possible to extract both the critical parameters and the critical exponent of the transition, the latter being in good agreement with the value obtained in numerical simulations of the 3D Anderson model.
Physical Review Letters 01/2009; 101(25):255702. · 7.37 Impact Factor
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ABSTRACT: We study the dynamics of an ultracold boson gas in a lattice submitted to a constant force. We track the route of the system towards chaos created by the many-body-induced nonlinearity and show that relevant information can be extracted from an experimentally accessible quantity, the gas mean position. The threshold nonlinearity for the appearance of chaotic behavior is deduced from Kolmogorov-Arnold-Moser arguments and agrees with the value obtained by calculating the associated Lyapunov exponent.
Physical Review Letters 11/2008; 101(14):144103. · 7.37 Impact Factor
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ABSTRACT: We present an approach of the kicked rotor quantum resonances in position-space, based on its analogy with the optical Talbot effect. This approach leads to a very simple picture of the physical mechanism underlying the dynamics and to analytical expressions for relevant physical quantities, such as mean momentum or kinetic energy. The ballistic behavior, which is closely associated to quantum resonances, is analyzed and shown to emerge from a coherent adding of successive kicks applied to the rotor thanks to a periodic reconstruction of the spatial wavepacket.
12/2007;
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ABSTRACT: We realize experimentally an atom-optics quantum chaotic system, the quasiperiodic kicked rotor, which is equivalent to a 3D disordered system, that allow us to demonstrate the Anderson metal-insulator transition. Sensitive measurements of the atomic wavefunction dynamics and the use of finite-size scaling techniques make it possible to extract both the critical parameters and the critical exponent of the transition, which is in good agreement with the value obtained in numerical simulations of the 3D Anderson model.
10/2007;
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ABSTRACT: In this article we discuss a teleportation scheme of coherent states of cavity field. The experimental realization proposed makes use of cavity quatum electrodynamics involving the interaction of Rydberg atoms with micromaser and Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role of auxiliary systems used to teleport the state from a micromaser cavity to another. We show that, even if the correct atomic detection fails in the first trials, one can succeed in teleportating the cavity field state if the proper measurement occurs in a later atom.
04/2007;
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ABSTRACT: We study the destruction of dynamical localization experimentally observed in an atomic realization of the kicked rotor by a deterministic Hamiltonian perturbation, with a temporal periodicity incommensurate with the principal driving. We show that the destruction is gradual, with well-defined scaling laws for the various classical and quantum parameters, in sharp contrast to predictions based on the analogy with Anderson localization.
Physical Review Letters 01/2007; 97(26):264101. · 7.37 Impact Factor
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ABSTRACT: We study the destruction of dynamical localization, experimentally observed in an atomic realization of the kicked rotor, by a deterministic Hamiltonian perturbation, with a temporal periodicity incommensurate with the principal driving. We show that the destruction is gradual, with well defined scaling laws for the various classical and quantum parameters, in sharp contrast with predictions based on the analogy with Anderson localization.
08/2006;
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ABSTRACT: Dynamical localization is a localization phenomenon taking place, for example, in the quantum periodically driven kicked rotor. It is due to subtle quantum destructive interferences and is thus of intrinsic quantum origin. It has been shown that deviation from strict periodicity in the driving rapidly destroys dynamical localization. We report experimental results showing that this destruction is partially reversible when the deterministic perturbation that destroyed it is slowly reversed. We also provide an explanation for the partial character of the reversibility.
Physical Review Letters 01/2006; 95(23):234101. · 7.37 Impact Factor
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ABSTRACT: This paper presents general results concerning the quantum dynamics in a tilted, time-modulated, one-dimensional, optical lattice. A dynamic equation describing the atomic motion is analytically solved, and the solution used to characterize the corresponding dynamics through the spatial mean position and dispersion of the wavepacket. The analysis of such quantities gives a quite complete picture of the quantum dynamics, and provides evidence for the central role of the quantum coherence.
Journal of Optics B Quantum and Semiclassical Optics 05/2004; 6(7):301. · 1.81 Impact Factor
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ABSTRACT: Subtle internal interference effects allow quantum-chaotic systems to display "sub-Fourier" resonances, i.e. to distinguish two neighboring driving frequencies in a time shorter than the inverse of the difference of the two frequencies. We report experiments on the atomic version of the kicked rotor showing the unusual properties of the sub-Fourier resonances, and develop a theoretical approach (based on the Floquet theorem) explaining these properties, and correctly predicting the widths and lineshapes.
02/2004;
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ABSTRACT: A widely accepted definition of "quantum chaos" is "the behavior of a quantum system whose classical limit is chaotic." The dynamics of quantum-chaotic systems is nevertheless very different from that of their classical counterparts. A fundamental reason for that is the linearity of Schrödinger equation. In this paper, we study the quantum dynamics of an ultracold quantum degenerate gas in a tilted optical lattice and show that it displays features very close to classical chaos. We show that its phase space is organized according to the Kolmogorov-Arnold-Moser theorem.
Physical Review Letters 12/2003; 91(21):210405. · 7.37 Impact Factor
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ABSTRACT: This paper presents a formalism describing the dynamics of a quantum particle in a one-dimensional, time-dependent, tilted lattice. The formalism uses the Wannier-Stark states, which are localized in each site of the lattice, and provides a simple framework allowing fully-analytical developments. Analytic solutions describing the particle motion are explicit derived, and the resulting dynamics is studied.
08/2003;
