69 research outputs found
On-chip III-V monolithic integration of heralded single photon sources and beamsplitters
We demonstrate a monolithic III-V photonic circuit combining a heralded
single photon source with a beamsplitter, at room temperature and telecom
wavelength. Pulsed parametric down-conversion in an AlGaAs waveguide generates
counterpropagating photons, one of which is used to herald the injection of its
twin into the beamsplitter. We use this configuration to implement an
integrated Hanbury-Brown and Twiss experiment, yielding a heralded second-order
correlation that confirms single-photon
operation. The demonstrated generation and manipulation of quantum states on a
single III-V semiconductor chip opens promising avenues towards real-world
applications in quantum information
Anisotropic spin-orbit induced splitting of intersubband spin plasmons
The anisotropic splitting of intersubband spin plasmons, resulting from spin-orbit coupling, is studied by angle-resolved inelastic light scattering on a [001]-oriented GaAs/AlGaAs quantum well. Confirming theoretical predictions made in [C. A. Ullrich and M. A. Flatte, Phys. Rev. B ´ 68, 235310 (2003)], this splitting is proven to exhibit a characteristic two-fold symmetry with the in-plane orientation, and to increase with increasing modulus of the excitation momentum. This opens the way to a more complete investigation, aiming at evidencing the existence of a collective spin-orbit field driving these excitations.Fil: Baboux, F.. Universite de Paris Vi. Institut Des Nanosciences de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Perez, F. Universite de Paris Vi. Institut Des Nanosciences de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Ullrich, C. A. . University Of Missouri; Estados UnidosFil: D'Amico, I. . University Of York; Reino UnidoFil: Gomez, Javier Enrique. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Centre National de la Recherche Scientifique; Francia. Universite de Paris Vi. Institut Des Nanosciences de Paris; FranciaFil: Bernard, M.. Universite de Paris Vi. Institut Des Nanosciences de Paris; Franci
Unstable and stable regimes of polariton condensation
Modulational instabilities play a key role in a wide range of nonlinear
optical phenomena, leading e.g. to the formation of spatial and temporal
solitons, rogue waves and chaotic dynamics. Here we experimentally demonstrate
the existence of a modulational instability in condensates of cavity
polaritons, arising from the strong coupling of cavity photons with quantum
well excitons. For this purpose we investigate the spatiotemporal coherence
properties of polariton condensates in GaAs-based microcavities under
continuous-wave pumping. The chaotic behavior of the instability results in a
strongly reduced spatial and temporal coherence and a significantly
inhomogeneous density. Additionally we show how the instability can be tamed by
introducing a periodic potential so that condensation occurs into negative mass
states, leading to largely improved coherence and homogeneity. These results
pave the way to the exploration of long-range order in dissipative quantum
fluids of light within a controlled platform.Comment: 7 pages, 5 figure
Hybrid III-V/Silicon photonic circuits embedding generation and routing of entangled photon pairs
The demand for integrated photonic chips combining the generation and
manipulation of quantum states of light is steadily increasing, driven by the
need for compact and scalable platforms for quantum information technologies.
While photonic circuits with diverse functionalities are being developed in
different single material platforms, it has become crucial to realize hybrid
photonic circuits that harness the advantages of multiple materials while
mitigating their respective weaknesses, resulting in enhanced capabilities.
Here, we demonstrate a hybrid III-V/Silicon quantum photonic device combining
the strong second-order nonlinearity and compliance with electrical pumping of
the III-V semiconductor platform with the high maturity and CMOS compatibility
of the silicon photonic platform. Our device embeds the spontaneous parametric
down-conversion (SPDC) of photon pairs into an AlGaAs source and their
subsequent routing to a silicon-on-insulator circuitry, within an evanescent
coupling scheme managing both polarization states. This enables the on-chip
generation of broadband telecom photons by type 0 and type 2 SPDC from the
hybrid device, at room temperature and with internal pair generation rates
exceeding for both types, while the pump beam is strongly
rejected. Two-photon interference with 92% visibility (and up to 99% upon 5 nm
spectral filtering) proves the high energy-time entanglement quality
characterizing the produced quantum state, thereby enabling a wide range of
quantum information applications on-chip, within an hybrid architecture merging
the assets of two mature and highly complementary platforms in view of
out-of-the-lab deployment of quantum technologies
Spin-Orbit Twisted Spin Waves : Group Velocity Control
We present a theoretical and experimental study of the interplay between spin-orbit coupling (SOC), Coulomb interaction, and motion of conduction electrons in a magnetized two-dimensional electron gas. Via a transformation of the many-body Hamiltonian we introduce the concept of spin-orbit twisted spin waves, whose energy dispersions and damping rates are obtained by a simple wave-vector shift of the spin waves without SOC. These theoretical predictions are validated by Raman scattering measurements. With optical gating of the density, we vary the strength of the SOC to alter the group velocity of the spin wave. The findings presented here differ from that of spin systems subject to the Dzyaloshinskii-Moriya interaction. Our results pave the way for novel applications in spin-wave routing devices and for the realization of lenses for spin waves
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