Quantum Division The notion of quantum mechanics is that variables are expressed as integer values. In fluids, for instance, vortices quantized in terms the polarization and phase shifts observed multiples 2π, is, full rotations each variable around vortex core. Theoretical work has predicted some instances there should be half-quantum vortices, where circumventing core characterized by just π polarization. By observing exciton-polariton condensates Lagoudakis et al. (p. 974 ) present...

Photoluminescence at low temperature is studied for a CdTe-based microcavity tuned to resonance with quantum well exciton. Two distinct stimulation effects are observed increasing excitation. The first one associated the lower polariton state in strong exciton-photon coupling regime. This effect, whose physical origin has not yet been identified, could be favored by higher stability of exciton CdTe. second stimulation, obtained much excitation, can assigned electron-hole plasma weak

We report on the observation of spontaneous coherent oscillations in a microcavity polariton bosonic Josephson junction. Condensation exciton polaritons here takes place under incoherent excitation double potential well naturally formed disorder. Coherent set at an power above condensation threshold. The time resolved population and phase dynamics reveal analogy with ac effect. A theoretical two-mode model describes observed effects, explaining how different realizations pulsed experiment...

We measure the polariton distribution function and condensation threshold versus photon-exciton detuning lattice temperature in a CdTe microcavity under nonresonant pumping. The results are reproduced by simulations using semiclassical Boltzmann equations. At negative we find kinetic regime: is not thermal governed relaxation kinetics. positive detuning, becomes thermodynamic parameters of system. Both regimes manifestation lasing, whereas only latter related to Bose-Einstein defined as an...

The fundamental mechanisms which control the phase coherence of polariton Bose-Einstein condensate (BEC) are determined. It is shown that combination number fluctuations and interactions leads to decoherence with a characteristic Gaussian decay first-order correlation function. This line shape, long times ( approximately 150 ps) both first- second-order functions, explained quantitatively by quantum-optical model takes into account interactions, fluctuations, gain loss in system. Interaction...

We observe dramatic changes in the near-field and far-field emission from a semiconductor microcavity excited by pulsed nonresonant optical pump with varying power. Above threshold pumping power, light is emitted single quantum state lying at bottom of lower exciton-polariton band. Its intensity increases exponentially power its linewidth becomes narrower than cavity mode width. Near-field spectroscopy shows that stimulated comes several bright spots plane, but no diffraction-induced angular...

We report on evidence for polariton condensation out of a reservoir incoherent polaritons. Polariton population and first-order coherence are investigated by spectroscopic imaging the far-field emission CdTe-based microcavity under nonresonant pumping. With increasing pumping power, stimulated with thresholdlike behavior spectral narrowing is observed in strong exciton-photon coupling regime. show that it comes from narrow ring k space, exhibiting enhanced spatial angular at stimulation onset.

The experimental investigation of spontaneously created vortices is utmost importance for the understanding quantum phase transitions towards a superfluid phase, especially two-dimensional systems that are expected to be governed by Berezinski-Kosterlitz-Thouless physics. By means time-resolved near-field interferometry we track path such vortices, at random locations in an exciton-polariton condensate under pulsed nonresonant excitation, their final pinning positions imposed stationary...

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 occur particle density distribution, under particular experimental conditions. this work we report on spontaneous pattern formation polariton condensate nonresonant optical pumping. The slightly elliptical ring-shaped excitation laser that employ forces to into single-energy state with periodic boundary...

We demonstrate that, even in unstrained GaN quantum wells with AlGaN barriers, there exist giant electric fields as high 1.5 MV/cm. These fields, resulting from the interplay of piezoelectric and spontaneous polarizations well barrier layers due to Fermi level alignment, induce large redshifts photoluminescence energy position dramatically increase carrier lifetime thickness increases.

We report on time-integrated and -resolved photoluminescence (PL) data self-assembled GaN quantum dots (QD's) embedded in AlN, both cubic [zinc-blende (ZB)] hexagonal [wurtzite (Wz)] crystallographic phases. The comparison of the optical properties ZB Wz nitride QD's allows us to distinguish pure dimensionality effects from influence large polarization-induced electric fields present nanostructures. Specifically, PL energy is always higher than bulk band-gap energy, contrast where a 7-MV/cm...

Second-order time correlations of polaritons have been measured across the condensation threshold in a CdTe microcavity. The onset Bose-Einstein is marked by disappearance photon bunching, demonstrating transition from thermal-like state to coherent state. Coherence is, however, degraded with increasing polariton density, most probably as result self-interaction within condensate and scatterings noncondensed excitons polaritons. Such behavior clearly differentiates Bose lasing.

We present a high-temperature single-photon source based on quantum dot inside nanowire. The nanowires were grown by molecular beam epitaxy in the vapor-liquid-solid growth mode. utilize two-step process that allows thin, defect-free ZnSe nanowire to grow top of broader, cone-shaped Quantum dots are formed incorporating narrow zone CdSe into observe intense and highly polarized photoluminescence even from single emitter. Efficient photon antibunching is observed up 220 K, while conserving...

Real- and momentum-space spectrally resolved images of microcavity polariton emission in the regime condensation are investigated under nonresonant excitation using a laser source with reduced intensity fluctuations on time scale exciton lifetime. We observe that consists many macroscopically occupied modes. Lower-energy modes strongly localized by spatial polaritonic potential disorder few microns. Higher-energy have finite $k$ vectors delocalized over $10--15\text{...

Condensation of exciton polaritons in semiconductor microcavities takes place despite in-plane disorder. Below the critical density, inhomogeneity disorder limits spatial extension ground state. Above presence weak disorder, this limitation is spontaneously overcome by nonlinear interaction, resulting an extended synchronized phase. In case strong several non-phase-locked condensates can be evidenced. The transition from a phase to desynchronized addressed sampling cavity

Epitaxial semiconductor quantum dots are particularly promising as realistic single-photon sources for their compatibility with manufacturing techniques and possibility to be implemented in compact devices. Here, we demonstrate the first time emission up room temperature from an epitaxial dot inserted a nanowire, namely CdSe slice ZnSe nanowire. The exciton biexciton lines can still resolved at turns out most appropriate transition due large nonradiative decay of bright dark states. With...

The degree of circular polarization ( Weierstrass p ) the nonlinear emission in semiconductor microcavities is controlled by changing exciton-cavity detuning. polariton relaxation towards K approximately 0 cavitylike states governed final-state stimulated scattering. helicity selected due to lifting degeneracy +/-1 spin levels at 0. At short times after a pulsed excitation reaches very large values, either positive or negative, as result scattering level lowest energy (+1/-1 for...

The linear polarization degree of the photoluminescence from a nonresonantly pumped CdTe microcavity exhibits dramatic increase about 0 to more than 85% once threshold stimulated scattering exciton polaritons toward Bose-Einstein condensate is passed. direction pinned one crystallographic axes cavity. These effects are well accounted for within model localized interacting bosons.

The quest for identification and understanding of fractional vorticity is a major subject research in the quantum fluids domain, ranging from superconductors, superfluid Helium-3 to cold atoms. In two-dimensional Bose degenerate gas with spin degree freedom, fundamental topological excitations are vortical entities, called half-quantum vortices. Convincing evidence existence vortices was recently provided spinor polariton condensates. can be regarded as structural components singly charged...

Polariton condensates have proved to be model systems investigate topological defects, as they allow for direct and nondestructive imaging of the condensate complex order parameter. The fundamental excitations such are quantized vortices. In specific configurations, further ordering can bring formation vortex lattices. this work we demonstrate spontaneous ordered vortical states, consisting in geometrically self-arranged vortex-antivortex pairs. A mean-field generalized Gross-Pitaevskii...