Publications de Konstantinos Lagoudakis

Spontaneous self-ordered states of vortex-antivortex pairs in a polariton condensate

Vincenzo Savona, Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Timothy Chi Hin Liew, Francesco Manni, Claudéric Ouellet-Plamondon

Polariton condensates have proved to be model systems to investigate topological defects, as they allow for direct and nondestructive imaging of the condensate complex order parameter. The fundamental topological excitations of such systems are quantized v ...

American Physical Society2013

Penrose-Onsager Criterion Validation in a One-Dimensional Polariton Condensate

Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Francesco Manni

We perform quantum tomography on one-dimensional polariton condensates, spontaneously occurring in linear disorder valleys in a CdTe planar microcavity sample. By the use of optical interferometric techniques, we determine the first-order coherence functio ...

Amer Physical Soc2012

Dissociation dynamics of singly charged vortices into half-quantum vortex pairs

Vincenzo Savona, Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Timothy Chi Hin Liew, Francesco Manni

The quest for identification and understanding of fractional vorticity is a major subject of research in the quantum fluids domain, ranging from superconductors, superfluid Helium-3 to cold atoms. In a two-dimensional Bose degenerate gas with a spin degree ...

Nature Publishing Group2012

Spin-to-orbital angular momentum conversion in semiconductor microcavities

Benoît Marie Joseph Deveaud, François Morier-Genoud, Taofiq Paraïso, Konstantinos Lagoudakis, Roland Cerna, Timothy Chi Hin Liew, Francesco Manni

We experimentally demonstrate a technique for the generation of optical beams carrying orbital angular momentum using a planar semiconductor microcavity. Despite being isotropic systems with no structural gyrotropy, semiconductor microcavities, because of ...

2011

Spontaneous Pattern Formation in a Polariton Condensate

Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Timothy Chi Hin Liew, Francesco Manni

Exciton-polariton condensation can be regarded as a self-organization phenomenon, where phase ordering is established among particles in the system. In such condensed systems, further ordering can occur in the particle density distribution, under particula ...

2011

Polariton Condensation in a One-Dimensional Disordered Potential

Vincenzo Savona, Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Barbara Pietka, Luca Fontanesi, Francesco Manni

We study the coherence and density modulation of a nonequilibrium exciton-polariton condensate in a one-dimensional valley with disorder. By means of interferometric measurements we evidence a modulation of the ﬁrst-order coherence function and we relate i ...

American Physical Society2011

On the Physics of Exciton-Polariton Condensates

Konstantinos Lagoudakis

After the first demonstration of Bose Einstein condensation in the solid state in 2006 and the establishment of exciton polariton condensates in the wider scientific community, an intense interest has been attracted by this phenomenon at both theoretical a ...

EPFL2010

Exciton-polariton Bose-Einstein condensation: advances and issues

Benoît Marie Joseph Deveaud, Stefan Kundermann, Konstantinos Lagoudakis

In this review, we present a comprehensive set of experimental results on microcavity-polariton Bose-Einstein Condensation (BEC), obtained within a close collaboration between Institut Neel, Grenoble, France and EPFL, Lausanne, Switzerland. First, we recal ...

Inderscience2010

Selective photoexcitation of confined exciton-polariton vortices

Benoît Marie Joseph Deveaud, François Morier-Genoud, Gaël Nardin, Konstantinos Lagoudakis, Barbara Pietka

We resonantly excite exciton-polariton states confined in cylindrical traps. Using a homodyne detection setup, we are able to image the phase and amplitude of the confined polariton states. We evidence the excitation of vortex states, carrying an integer a ...

2010

Dynamics of Long-Range Ordering in an Exciton-Polariton Condensate

Benoît Marie Joseph Deveaud, Gaël Nardin, Konstantinos Lagoudakis, Barbara Pietka

We report on time-resolved measurements of the first order spatial coherence in an exciton-polariton Bose-Einstein condensate. Long-range spatial coherence is found to set in right at the onset of stimulated scattering, on a picosecond time scale. The cohe ...

American Physical Society2009

Observation of Half Quantum Vortices in an Exciton-Polariton Condensate

Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis

Singly quantized vortices have already been observed in many systems, including the superfluid helium, Bose-Einstein condensates of dilute atomic gases, and condensates of exciton-polaritons in the solid state. Two-dimensional superfluids carrying spin are ...

American Association for the Advancement of Science2009

Coexisting nonequilibrium condensates with long-range spatial coherence in semiconductor microcavities

Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis, Barbara Pietka

Real- and momentum-space spectrally resolved images of microcavity polariton emission in the regime of condensation are investigated under nonresonant excitation using a laser source with reduced intensity fluctuations on the time scale of the exciton life ...

2009

Superconducting nanowire photon-number-resolving detector at telecommunication wavelengths

Francis Lévy, Francesco Marsili, Konstantinos Lagoudakis, Alessandro Gaggero

Optical-to-electrical conversion, which is the basis of the operation of optical detectors, can be linear or nonlinear. When high sensitivities are needed, single-photon detectors are used, which operate in a strongly nonlinear mode, their response being i ...

Nature Publishing Group2008

Quantized Vortices in an Exciton-Polariton Condensate

Benoît Marie Joseph Deveaud, Konstantinos Lagoudakis

One of the most striking quantum effects in an interacting Bose gas at low temperature is superfluidity. First observed in liquid 4He, this phenomenon has been intensively studied in a variety of systems for its remarkable features such as the persistence ...

Nature Publishing Group2008