A. Qarry

Scattering of polaritons by a two-dimensional electron gas in a semiconductor microcavity

Physical Review B, 2002

The effect of a classical electron gas on the cavity polariton linewidths is studied experimental... more

Polariton-Electron Scattering in a Semiconductor Microcavity

physica status solidi (a), 2002

The effect of a classical electron gas on the cavity polariton linewidths is studied experimental... more The effect of a classical electron gas on the cavity polariton linewidths is studied experimentally at T ¼ 80 K in a GaAs/AlAs microcavity with an embedded quantum well. The linewidth dependence on the electron density and on the cavity mode energy is explained by a theoretical model based on the asymmetric bare exciton line shape, due to electron-exciton scattering.

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Nonlinear emission due to electron-polariton scattering in a semiconductor microcavity

Physical Review B, 2003

Electron-polariton scattering is studied by photoluminescence spectroscopy in a GaAs/AlGaAs micro... more

Free electron effects on the cavity polariton linewidth in an AlAs/AlGaAs microcavity containing a two-dimensional electron gas

Solid State Communications, 2001

We report on an experimental study of the microcavity polariton linewidth in an AlAs/AlGaAs micro... more We report on an experimental study of the microcavity polariton linewidth in an AlAs/AlGaAs microcavity containing GaAs quantum wells (QW) in which a variable density electron gas is photogenerated. The linewidth of the lowest polariton branch shows a clear suppression while that of the other branches show enhancement at narrow detuning energy ranges. A transformation is observed from a strong to weak exciton-cavity mode coupling at a very low photoexcitation intensity.

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Magnetic field effect on the free electron–exciton scattering in GaAs/AlGaAs bare quantum wells and in microcavities

Physica E: Low-dimensional Systems and Nanostructures, 2002

We report on a detailed study of the free electron scattering effects on the (e1:hh1)1S and (e1:l... more We report on a detailed study of the free electron scattering effects on the (e1:hh1)1S and (e1:lh1)1S excitons in a GaAs quantum well with a variable density two-dimensional electron gas, that is either bare or embedded in a GaAs/AlGaAs microcavity. These effects are studied by measuring the reflection line width of the bare excitons or cavity polaritons as a function

Entanglement-assisted Delayed-Choice Experiment

2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007

Here we report a experimental realization of that assisted by polarization entanglement of photon... more Here we report a experimental realization of that assisted by polarization entanglement of photon pairs. Nearly perfect polarization correlation between two photons can be employed to this delayed-choice experiment and then enable the space-like separation of the &amp;amp;amp;amp;quot;choice-maker&amp;amp;amp;amp;quot; (which is the polarization projection of one photon done by a Pockel Cell controlled by Quantum Random Number Generator) and single photon

Polaritons in microcavities containing a two-dimensional electron gas

Semiconductor Science and Technology, 2003

We review the spectroscopic and dynamic properties of cavity polaritons in a lambda-wide GaAs/GaA... more We review the spectroscopic and dynamic properties of cavity polaritons in a lambda-wide GaAs/GaAlAs microcavity (MC) structure having a single GaAs/AlAs quantum well in which a variable density two-dimensional electron gas (2DEG) is photoexcited, with a density in the range 0 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; ne &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 5 × 1011 cm-2. The main observed effects that will be discussed here are: (a) photoexcitation

Electron-Exciton Scattering in a GaAs/AlAs Bare Quantum Well and in a Microcavity

physica status solidi (a), 2002

We report on a detailed study of the electron-exciton scattering in a GaAs quantum well (QW) with... more We report on a detailed study of the electron-exciton scattering in a GaAs quantum well (QW) with a variable density two-dimensional electron gas. Both a bare QW and a QW embedded in a GaAs/AlGaAs microcavity are studied by measuring the reflection linewidths of the bare excitons and the cavity polaritons as a function of photoexcitation intensity, temperature, and a perpendicularly applied magnetic field. This field induces the formation of charged polaritons at temperatures higher than the range of the charged exciton binding energy. The bare exciton linewidth dependence on electron density shows a transition when the electron gas transforms from classical to degenerate state. The lowest polariton linewidth dependence on electron gas and detuning energy is explained by the overlap of the cavity mode with the asymmetric exciton lineshape.

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A non-local quantum eraser

The complementarity behavior of quantum systems is strikingly illustrated by the quantum eraser, ... more The complementarity behavior of quantum systems is strikingly illustrated by the quantum eraser, where one can actively choose whether or not to erase which-path information of one particle by performing suitable measurements on another particle entangled with it [1-2]. Quantum mechanics predicts that this choice can be arbitrarily delayed and spatially separated from interference [1-3]. We report the first quantum eraser experiment performed under Einstein locality, i.e. under relativistic space-like separation. We employ the hybrid entanglement between path and polarization of photon pairs and distribute the photons over an optical fibre link of 55 m and, in another experiment, over a free-space link of 144 km. A complementarity inequality is measured and well fits the predictions of quantum mechanics. Our experiment represents a conclusive demonstration of the quantum eraser concept. [0pt] [1] M. O. Scully, K. Dr"uhl, Phys. Rev. A 25, 2208 (1982). [2] J. A. Wheeler, in Quantum Theory and Measurement (1984). [3] V. Jacques, et al., Science 315, 966 (2007).

Electron-polariton scattering in n-doped semiconductor microcavities

Markov logic networks (MLNs) are an expressive representation for statistical relational learning... more Markov logic networks (MLNs) are an expressive representation for statistical relational learning that generalizes both first-order logic and graphical models. Existing methods for learning the logical structure of an MLN are not discriminative; however, many relational learning problems involve specific target predicates that must be inferred from given background information. We found that existing MLN methods perform very poorly on several such ILP benchmark problems, and we present improved discriminative methods for learning MLN clauses and weights that outperform existing MLN and traditional ILP methods.

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A high-speed tunable beam splitter for feed-forward photonic quantum information processing

Optics Express, 2011

We realize quantum gates for path qubits with a high-speed, polarization-independent and tunable ... more We realize quantum gates for path qubits with a high-speed, polarization-independent and tunable beam splitter. Two electro-optical modulators act in a Mach-Zehnder interferometer as high-speed phase shifters and rapidly tune its splitting ratio. We test its performance with heralded single photons, observing a polarization-independent interference contrast above 95%. The switching time is about 5.6 ns, and a maximal repetition rate

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Quantum simulation of time-dependent Hamiltonians and the convenient illusion of Hilbert space

We consider the manifold of all quantum many-body states that can be generated by arbitrary time-... more We consider the manifold of all quantum many-body states that can be generated by arbitrary time-dependent local Hamiltonians in a time that scales polynomially in the system size, and show that it occupies an exponentially small volume in Hilbert space. This implies that the overwhelming majority of states in Hilbert space are not physical as they can only be produced after an exponentially long time. We establish this fact by making use of a time-dependent generalization of the Suzuki-Trotter expansion, followed by a counting argument. This also demonstrates that a computational model based on arbitrarily rapidly changing Hamiltonians is no more powerful than the standard quantum circuit model.

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01 9 v 2 9 O ct 2 00 6 Realization of a superconducting atom chip

We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip oper... more We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip operated at liquid Helium temperatures. Up to 8.2 • 10 5 atoms are held in a Ioffe-Pritchard trap at a distance of 440 µm from the chip surface, with a temperature of 40 µK. The trap lifetime reaches 115 s at low atomic densities. These results open the way to the exploration of atom-surface interactions and coherent atomic transport in a superconducting environment, whose properties are radically different from normal metals at room temperature.

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Bottleneck and resonant enhancement in free electron - cavity polaritons scattering in GaAs/AlGaAs microcavities

Springer Proceedings in Physics, 2001

The interaction between exciton states near the quantum well bandgap and confined photons in GaAs/AlAs microcavities

Springer Proceedings in Physics, 2001

Hybrid entanglement and a non-local quantum eraser

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009

We demonstrate for the first time hybrid entanglement of photon pairs generated via the experimen... more We demonstrate for the first time hybrid entanglement of photon pairs generated via the experimental violation of a Bell inequality with two different degrees of freedom (DOF), namely the path/linear momentum of one photon and the polarization of the other photon. Polarization entangled photon pairs are created by spontaneous parametric down conversion. Then, a modified Mach-Zehnder interferometer is used to

Realization of a superconducting atom chip

Physical review letters, 2006

We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip oper... more We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip operated at liquid Helium temperatures. Up to 8.2 • 10 5 atoms are held in a Ioffe-Pritchard trap at a distance of 440 µm from the chip surface, with a temperature of 40 µK. The trap lifetime reaches 115 s at low atomic densities. These results open the way to the exploration of atom-surface interactions and coherent atomic transport in a superconducting environment, whose properties are radically different from normal metals at room temperature.

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Electron‐polariton scattering, beneficial and detrimental effects

We study the effects of electron-polariton scattering in a semiconductor microcavity that allows ... more We study the effects of electron-polariton scattering in a semiconductor microcavity that allows control of the electron density. We show that this process can efficiently drive polaritons to the ground polariton state and that it is more effective whenever the relaxation bottleneck is present on the LP branch.

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Quantum erasure with causally disconnected choice

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Exciton polariton emission enhancement in semiconductor microcavities containing an optically induced electron gas

Postconference Digest Quantum Electronics and Laser Science, 2003. QELS., 2003

... Rev. B 65, 205310 (2002). 3. H. Deng, G. Weihs, C. Santori, J. Bloch, and Y. Yamamoto, Scienc... more

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