References of "Martin, John"
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See detailThe quest for highly entangled symmetric states
Martin, John ULg

Scientific conference (2012, June 05)

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See detailHeisenberg-limited Metrology without Entanglement
Braun, Daniel; Martin, John ULg

in Research in Optical Sciences, OSA Technical Digest (2012)

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See detailHeisenberg-limited metrology without entanglement
Braun, Daniel; Martin, John ULg

Conference (2012, March)

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See detailHeisenberg-limited metrology without entanglement
Braun, Daniel; Martin, John ULg

Conference (2012, January)

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See detailMultiqubit symmetric states with a high geometric entanglement
Martin, John ULg; Giraud, Olivier; Braun, Peter et al

Poster (2011, May 25)

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric ... [more ▼]

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric entanglement and how their entanglement behaves asymptotically for large N. We show that much higher geometric entanglement with improved asymptotical behavior can be obtained in comparison with the highly entangled balanced Dicke states studied previously. We also derive an upper bound for the geometric measure of entanglement of symmetric states. The connection with the quantumness of a state is discussed. [less ▲]

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See detailHeisenberg-limited sensitivity with decoherence-enhanced measurements
Braun, D.; Martin, John ULg

in Nature Communications (2011), 2(223), 1-9

Quantum-enhanced measurements use quantum mechanical effects to enhance the sensitivity of the measurement of classical quantities, such as the length of an optical cavity. The major goal is to beat the ... [more ▼]

Quantum-enhanced measurements use quantum mechanical effects to enhance the sensitivity of the measurement of classical quantities, such as the length of an optical cavity. The major goal is to beat the standard quantum limit (SQL), that is, an uncertainty of order 1/ N, where N is the number of quantum resources (for example, the number of photons or atoms used), and to achieve a scaling 1/N, known as the Heisenberg limit. So far very few experiments have demonstrated an improvement over the SQL. The required quantum states are generally highly entangled, difficult to produce, and very prone to decoherence. Here, we show that Heisenberg- limited measurements can be achieved without the use of entangled states by coupling the quantum resources to a common environment that can be measured at least in part. The method is robust under decoherence, and in fact the parameter dependence of collective decoherence itself can be used to reach a 1/N scaling. [less ▲]

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See detailMultiqubit symmetric states with a high geometric entanglement
Martin, John ULg; Giraud, O.; Braun, P. A. et al

Poster (2010, July)

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See detailMultifractality in the kicked rotator
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

Poster (2010, July)

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See detailMultifractality in quantum maps
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

Poster (2010, March)

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See detailMultiqubit symmetric states with high geometric entanglement
Martin, John ULg; Giraud, O.; Braun, P. A. et al

in Physical Review. A (2010), 81(6), 0623471-6

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric ... [more ▼]

We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric entanglement and how their entanglement behaves asymptotically for large N. We show that much higher geometric entanglement with improved asymptotical behavior can be obtained in comparison with the highly entangled balanced Dicke states studied previously. We also derive an upper bound for the geometric measure of entanglement of symmetric states. The connection with the quantumness of a state is discussed. [less ▲]

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See detailMultifractal wave functions of simple quantum maps
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2010), 82

We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like ... [more ▼]

We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like transition recently implemented with cold atoms. Using extensive numerical simulations, we compute the multifractal exponents of quantum wave functions and study their properties, with the help of two different numerical methods used for classical multifractal systems (box-counting and wavelet methods). We compare the results of the two methods over a wide range of values. We show that the wave functions of the Anderson map display a multifractal behavior similar to eigenfunctions of the three-dimensional Anderson transition but of a weaker type. Wave functions of the intermediate map share some common properties with eigenfunctions at the Anderson transition (two sets of multifractal exponents, with similar asymptotic behavior), but other properties are markedly different (large linear regime for multifractal exponents even for strong multifractality, different distributions of moments of wave functions, and absence of symmetry of the exponents). Our results thus indicate that the intermediate map presents original properties, different from certain characteristics of the Anderson transition derived from the nonlinear sigma model. We also discuss the importance of finite-size effects. [less ▲]

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See detailEntanglement of random localized and multifractal states
Martin, John ULg; Giraud, Olivier; Georgeot, Bertrand

Conference (2009, August)

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See detailTime reversal of Bose-Einstein condensates
Martin, John ULg; Georgeot, Bertrand; Shepelyansky, Dima

Poster (2009, July)

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See detailDecoherence-enhanced measurements
Braun, Daniel; Martin, John ULg

Conference (2009, May)

Detailed reference viewed: 13 (0 ULg)
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See detailEntropy of entanglement and multifractal exponents for random states
Giraud, O.; Martin, John ULg; Georgeot, B.

in Physical Review. A (2009), 79

We relate the entropy of entanglement of ensembles of random vectors to their generalized fractal dimensions. Expanding the von Neumann entropy around its maximum we show that the first order only depends ... [more ▼]

We relate the entropy of entanglement of ensembles of random vectors to their generalized fractal dimensions. Expanding the von Neumann entropy around its maximum we show that the first order only depends on the participation ratio, while higher orders involve other multifractal exponents. These results can be applied to entanglement behavior near the Anderson transition. [less ▲]

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See detailChaotic dynamics of a Bose-Einstein condensate coupled to a qubit
Martin, John ULg; Georgeot, B.; Shepelyansky, D. L.

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2009), 79

We study numerically the coupling between a qubit and a Bose-Einstein condensate (BEC) moving in a kicked optical lattice, using Gross-Pitaevskii equation. In the regime where the BEC size is smaller than ... [more ▼]

We study numerically the coupling between a qubit and a Bose-Einstein condensate (BEC) moving in a kicked optical lattice, using Gross-Pitaevskii equation. In the regime where the BEC size is smaller than the lattice period, the chaotic dynamics of the BEC is effectively controlled by the qubit state. The feedback effects of the nonlinear chaotic BEC dynamics preserve the coherence and purity of the qubit in the regime of strong BEC nonlinearity. This gives an example of an exponentially sensitive control over a macroscopic state by internal qubit states. At weak nonlinearity quantum chaos leads to rapid dynamical decoherence of the qubit. The realization of such coupled systems is within reach of current experimental techniques. [less ▲]

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See detailEntanglement and Localization of Wavefunctions
Giraud, Olivier; Georgeot, Bertrand; Martin, John ULg

in Complex Phenomena in Nanoscale Systems, NATO Science for Peace and Security Series B: Physics and Biophysics, Volume . ISBN 978-90-481-3118-1. Springer Netherlands, 2009, p. 51 (2009)

We review recent works that relate entanglement of random vectors to their localization properties. In particular, the linear entropy is related by a simple expression to the inverse participation ratio ... [more ▼]

We review recent works that relate entanglement of random vectors to their localization properties. In particular, the linear entropy is related by a simple expression to the inverse participation ratio, while next orders of the entropy of entanglement contain information about e.g. the multifractal exponents. Numerical simulations show that these results can account for the entanglement present in wavefunctions of physical systems. [less ▲]

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See detailInterference in the light emitted by a single tunneling atom
Martin, John ULg; Braun, Daniel

Poster (2008, July)

Detailed reference viewed: 5 (0 ULg)
See detailTime Reversal of Atomic Matter Waves
Martin, John ULg; Georgeot, Bertrand; Shepelyansky

Poster (2008, May)

Detailed reference viewed: 5 (0 ULg)
See detailSpontaneous emission from a tunneling atom
Braun, Daniel; Martin, John ULg

Conference (2008, March)

Detailed reference viewed: 5 (0 ULg)