Black Holes and Wormholes in spinor polariton condensates

Comment on "Topological stability of the half-vortices in spinor exciton-polariton condensates"

We show that recent paper by Flayac et al. [Phys. Rev. B 81, 045318 (2010) and arXiv:0911.1650] is misleading. We demonstrate the existence of static half-quantum vortices in exciton-polariton condensates and calculate the warping of their polarization texture produced by TE-TM splitting of polariton band.

Optical bistability under non-resonant excitation in spinor polariton condensates

We realise bistability in the spinor of polariton condensates under non-resonant optical excitation and in the absence of biasing external fields. Numerical modelling of the system using the Ginzburg-Landau equation with an internal Josephson coupling between the two spin components of the condensate qualitatively describes the experimental observations. We demonstrate that polariton spin bistability persists for sweep times in the range of $[10 μsec,1 sec]$ offering a promising route to spin switches and spin memory elements.

Stable magnetic monopoles in spinor polariton condensates

We consider half-integer topological defects in a spinor Bose-Einstein condensate of exciton-polaritons. We show that they accelerate under the effect of an in-plane effective magnetic field, like regular electric charges in the electric field. The trajectories of these analogues of magnetic monopoles are derived analytically and checked by numerical simulations. We show that these "magnetic charges" propagate at large in-plane velocities and remain stable up to a critical magnetic field, thanks to the unique spin-anisotropy of polariton interactions.

面向旋量极化激元模拟器的扩展XY模型

Extended XY model for spinor polariton simulators

针对经典晶格XY模型的旋量极化激元凝聚体实现场景，研究引入腔极化激元偏振自由度的影响，构建耦合相位与偏振的经典自旋哈密顿量，揭示标量与旋量情形的本质差异，并探讨自旋迈斯纳效应的类比形式。

Coherence Revivals of a Spinor Polariton Condensate from Self-induced Larmor Precession

First order coherence measurements of a polariton condensate, reveal a regime where the condensate pseudo-spin precesses persistently within the driving optical pulse. Within a single 20 $μ$s optical pulse the condensate pseudo-spin performs over $10^5$ precessions with striking frequency stability. The condensate maintains its phase coherence even after a complete precession of the spin vector, making the observed state by a definition a spin coherent state. The emergence of the precession is traced to the polariton interactions that give rise to a self-induced out-of-plane magnetic field tha…

Spinor superfluid currents of exciton-polaritons on a split-ring

Recently, split-ring bosonic condensates of exciton polaritons have been proposed for realisation of qubits. We formulate an analytical model of a polariton condensate in a one-dimensional ring split by a delta-function potential. The persistent current is stopped by the potential defect embedded in a scalar condensate of non-interacting particles, however, it reappears in the presence of an up-critical non-linearity. The nonlinear supercurrents are characterised by fractional orbital momenta while their eigenfunctions may feature grey or dark solitons. The coupling between the spin and the or…

Probing the collective excitations of a spinor polariton fluid

We propose a pump-probe set-up to analyse the properties of the collective excitation spectrum of a spinor polariton fluid. By using a linear response approximation scheme, we carry on a complete classification of all excitation spectra, as well as their intrinsic degree of polarisation, in terms of two experimentally tunable parameters only, the mean-field polarisation angle and a rescaled pump detuning. We evaluate the system response to the external probe, and show that the transmitted light can undergo a spin rotation along the dispersion for spectra that we classify as diffusive-like. We …

Non-conservative Lagrangian method for half-dark solitons in spinor non-equilibrium Polariton condensates

In this work I introduce a powerful analytical method to analyze states of non-equilibrium polariton Bose-Einstein condensates (BEC). It is shown that the condensate wave functions carrying dark solitons and half-dark solitons can be expressed in terms of the natural parameters of the non-equilibrium system, i.e. the growth and decay rates and the interaction parameters. The derivation is based on a non-conservative Lagrangian formalism, which provides ordinary differential equations for the parameters of the dark soliton solutions in their dynamic environment. Explicit expressions for the sta…

Topological spin Meissner effect in exciton-polariton spinor condensate: constant amplitude solutions, half-vortices and symmetry breaking

We generalize the spin Meissner effect for exciton-polariton condensate confined in annular geometries to the case of non-trivial topology of the condensate wavefunction. In contrast to the conventional spin Meissner state, topological spin Meissner states can in principle be observed at arbitrary high magnetic field not limited by the critical magnetic field value for the condensate in a simply-connected geometry. One special example of the topological Meissner states are half-vortices. We show that in the absence of magnetic field half-vortices in a ring exist in a form of superposition of e…

Collective excitations of exciton-polariton condensates in a synthetic gauge field

Collective (elementary) excitations of quantum bosonic condensates, including condensates of exciton polaritons in semiconductor microcavities, are a sensitive probe of interparticle interactions. In anisotropic microcavities with momentum-dependent TE-TM splitting of the optical modes, the excitations dispersions are predicted to be strongly anisotropic, which is a consequence of the synthetic magnetic gauge field of the cavity, as well as the interplay between different interaction strengths for polaritons in the singlet and triplet spin configurations. Here, by directly measuring the disper…

Reply to "Comment on 'Topological stability of the half-vortices in spinor exciton-polariton condensates'"

In a recent work [H. Flayac, I.A. Shelykh, D.D. Solnyshkov and G. Malpuech, Phys. Rev. B 81, 045318 (2010)], we have analyzed the effect of the TE-TM splitting on the stability of the exciton-polariton vortex states. We considered classical vortex solutions having cylindrical symmetry and we found that the so-called half-vortex states [Yu. G. Rubo, Phys. Rev. Lett. 99, 106401 (2007)] are not solutions of the stationary Gross-Pitaevskii equation. In their Comment [M. Toledo Solano, Yu.G. Rubo, Phys. Rev. B 82, 127301 (2010)], M. Toledo Solano and Yuri G. Rubo claim that this conclusion is misle…

对称性破缺与分裂环自旋极化激元凝聚体中的超流体电流

Symmetry breaking and superfluid currents in a split-ring spinor polariton condensate

本文研究了被势垒分裂的环上激子极化激元自旋凝聚体中顺时针与逆时针电流的对称性破缺现象，揭示了粒子间相互作用如何引发全局旋转恢复或圆偏振出现。

Polariton Spin Whirls

We report on the observation of spin whirls in a radially expanding polariton condensate formed under non-resonant optical excitation. Real space imaging of polarization- and time-resolved photoluminescence reveal a spiralling polarization pattern in the plane of the microcavity. Simulations of the spatiotemporal dynamics of a spinor condensate reveal the crucial role of polariton interactions with a spinor exciton reservoir. Harnessing spin dependent interactions between the exciton reservoir and polariton condensates allows for the manipulation of spin currents and the realization of dynamic…

Spontaneous spin bifurcations and ferromagnetic phase transitions in a spinor exciton-polariton condensate

We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly-polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for many seconds at 5 K, but at higher temperatures it can flip from one magnetic orientation to another. We optically address these states and demonstrate the inversion of the magne…

Optical Valley Hall Effect based on Transitional Metal Dichalcogenide cavity polaritons

We calculate the dispersion of spinor exciton-polaritons in a planar microcavity with its active region containing a single Transitional Metal Dichalcogenide (TMD) monolayer, taking into account excitonic and photonic spin-orbit coupling. We consider the radial propagation of polaritons in presence of disorder. We show that the reduction of the disorder scattering induced by the formation of polariton states allows to observe an optical Valley Hall effect, namely the coherent precession of the locked valley and polarization pseudospins leading to the formation of spatial valley-polarized domai…

Optical control of spin textures in quasi-one-dimensional polariton condensates

We investigate, through polarization-resolved spectroscopy, the spin transport by propagating polariton condensates in a quasi one-dimensional microcavity ridge along macroscopic distances. Under circularly polarized, continuous-wave, non-resonant excitation, a sinusoidal precession of the spin in real space is observed, whose phase depends on the emission energy. The experiments are compared with simulations of the spinor-polariton condensate dynamics based on a generalized Gross-Pitaevskii equation, modified to account for incoherent pumping, decay and energy relaxation within the condensate…

Spin-orbit coupled polariton condensates in a radially-periodic potential: Multiring vortices and rotating solitons

We address evolution of a spinor polariton condensate in radially periodic potentials. Such potentials allow for the observation of novel nonlinear excitations and support a variety of dynamically stable soliton states never demonstrated before in polariton condensates, including ring-like solitons with density peaks located in different radial minima of the potential and extended dynamically stable multiring patterns. Among the advantages of the system is that azimuthal modulational instabilities are suppressed due to dominating repulsive interactions between polaritons with the same spin, th…

Instability-induced formation and non-equilibrium dynamics of phase defects in polariton condensates

We study, theoretically and numerically, the onset and development of modulational instability in an incoherently pumped spatially homogeneous polariton condensate. Within the framework of mean-field theory, we identify regimes of modulational instability in two cases: 1) Strong feedback between the condensate and reservoir, which may occur in scalar condensates, and 2) Parametric scattering in the presence of polarization splitting in spinor condensates. In both cases we investigate the instability induced textures in space and time including non-equilibrium dynamics of phase dislocations and…

Ultralong temporal coherence in optically trapped exciton-polariton condensates

We investigate an optically trapped exciton-polariton condensate and observe temporal coherence beyond 1~ns duration. Due to the reduction of the spatial overlap with the thermal reservoir of excitons, the coherence time of the trapped condensate is more than an order of magnitude longer than that of an untrapped condensate. This ultralong coherence enables high precision spectroscopy of the trapped condensate, and we observe periodic beats of the field correlation function due to a fine energy splitting of two polarization modes of the condensate. Our results are important for realizing polar…

环形极化激元凝聚体中的持续极化振荡

Persistent polarization oscillations in ring-shape polariton condensates

本研究预测了光致旋转势阱中环形激子-极化激元玻色凝聚体的极限环解，揭示了旋量凝聚体特有的极化振荡效应，为基于不同拓扑荷极化激元凝聚体叠加态的量子比特调控提供了工具。

Interacting quantum fluid in a polariton topological insulator

We study Bogoliubov excitations of a spinor Bose Einstein condensate in a honeycomb periodic potential, in the presence of a Zeeman field and of a spin-orbit coupling specific for photonic systems, which is due to the energy splitting between TE and TM polarized eigenstates. We also consider spin-anisotropic interactions typical for cavity polaritons. We show that the non-trivial topology of the single particle case is also present for the interacting system. At low condensate density, the topology of the single-particle bands is transferred to the bogolon dispersion. At a critical value, the …

极化开关在极iton约瑟夫森结中的控制

Controlled Polarization Switch in a Polariton Josephson Junction

研究通过四模玻色约瑟夫森结探讨极iton-自旋轨道耦合的非线性动力学，发现参数范围内极化度可动态切换，为全光可控自旋开关提供新方案。

激子-极化激元凝聚体中的隐藏手性和半涡旋形成

Hidden chirality and half-vortex formation in exciton-polariton condensates

本文发现径向对称的非共振泵浦自旋激子-极化激元凝聚体无需旋转驱动或轨道角动量即可获得手性，通过双储层自旋弛豫产生非厄米手性势，实现半涡旋的全光形成。

Spin order and phase transitions in chains of polariton condensates

We demonstrate that multiply-coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed 4-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger 8 condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fu…

耦合极化激元凝聚体中的约瑟夫森电流和自旋电流

Josephson and Spin Currents in Coupled Polariton Condensates

本文分析自旋极化激元凝聚体网络中的粒子流和自旋流，通过能量最小化推导三角形和方形回路的边缘解析电流，并揭示自旋守恒与TE-TM隧穿产生的隐藏自旋逆流和键依赖自旋电流模式。

极子凝聚体中的声子自旋共振

Acoustic spin resonance in polariton condensates

研究极子凝聚体中声子自旋共振现象，通过声波产生有效磁场驱动极化振荡，揭示自旋依赖相互作用和非线性特性，以及非平衡态下的双稳态行为。

Magnetic dipolar modes in magnon-polariton condensates

For dipole-carrying excitations observed in a high-quality resonator, strong-coupling modes can appear as composite bosons with the spontaneous formation of quantized vortices in the condensed phase of a polariton fluid. In exciton-polaritons, in particular, it leads to sustained trapping of the emitted photon. In this paper, we show that magnon-polaritons can be realized due to magnon condensation caused by magnetic dipole-dipole interaction. In a quasi-2D ferrite disk placed in a microwave cavity, one observes quantum confinement effects of magnetic-dipolar-mode (MDM) oscillations. These mod…

Transverse instability of dark solitons in spin-orbit coupled polariton condensates

We consider dark solitons and their stability in spin-orbit coupled polariton condensates. The system supports spinor solitons of two types: conventional (symmetric) dark solitons and asymmetric half-dark solitons. They demonstrate essentially different behavior upon variation of the strength of spin-orbit coupling. One-dimensional spin-orbit coupled dark solitons are usually unstable, while half-dark solitons can be stable. Two-dimensional dark solitons at early stages of the development of transverse instabilities turn into asymmetric snaking patterns and later into sets of vortex-antivortex…

Effect of TE-TM Splitting on the topological stability of half-vortices in exciton-polariton condensates

Half-vortices have been recently shown to be the elementary topological defects supported by a spinor cavity exciton-polaritons condensates with spin anisotropic interactions (Y. G. Rubo, Phys. Rev. Lett. 99, 106401 (2007)). A half vortex is composed by an integer vortex for one circular component of the condensate, whereas the other component remain static. We analyze theoretically the effect of the splitting between TE and TM polarized eigen modes on the structure of the vortices in this system. For TE and TM modes, the polarization states depend on the direction of propagations of particles…