Spinning polariton vortices with magnetic field

This is an accepted manuscript of an article published by American Physical Society in Physical Review B on 12/03/2020, available online: https://doi.org/10.1103/PhysRevB.101.104308 The accepted version of the publication may differ from the final published version.We study the formation dynamics of spinor polariton condensates trapped in ring-shaped confining potentials created by excitonic reservoirs. We consider in detail the interplay of the effective spin-orbit interaction provided by transverse electric and transverse magnetic photonic modes splitting (TE-TM splitting) and exciton Zeeman splitting provided by an external magnetic field. We demonstrate that tuning of the trap size obtained by shaping of the external nonresonant and depolarized pumping allows formation of pairs of half-vortices of topological charges ±1/2 in both spin components. Further, we show that the probabilities of the realizations of four possible vortex configurations strongly depend on the value of the magnetic field. For certain values of the field, the probability of the formation of a vortex with desired topological charge reaches 90%, which opens the possibility of on-demand control of angular momentum of quantum fluids of light with a magnetic field.Published versio

Optically controlled polariton condensate molecules

This is an accepted manuscript of an article published by the American Physical Society in Physical Review B on 29/03/2021, available online: https://doi.org/10.1103/PhysRevB.103.115309 The accepted version of the publication may differ from the final published version.A condensed-matter platform for analog simulation of complex two-dimensional molecular bonding configurations, based on optically trapped exciton-polariton condensates is proposed. The stable occupation of polariton condensates in the excited states of their optically configurable potential traps permits emulation of excited atomic orbitals. A classical mean-field model describing the dissipative coupling mechanism between p-orbital condensates is derived, identifying lowest-threshold condensation solutions as a function of trap parameters corresponding to bound and antibound π and σ bonding configurations, similar to those in quantum chemistry.Published versio

Optical analogue of Dresselhaus spin–orbit interaction in photonic graphene

This is an accepted manuscript of an article published by Springer in Nature Photonics on 30/11/2020, available online: https://doi.org/10.1038/s41566-020-00729-z The accepted version of the publication may differ from the final published version.The concept of gauge fields plays a significant role in many areas of physics, from particle physics and cosmology to condensed-matter systems, where gauge potentials are a natural consequence of electromagnetic fields acting on charged particles and are of central importance in topological states of matter1. Here, we report on the experimental realization of a synthetic non-Abelian gauge field for photons2 in a honeycomb microcavity lattice3. We show that the effective magnetic field associated with transverse electric–transverse magnetic splitting has the symmetry of the Dresselhaus spin–orbit interaction around Dirac points in the dispersion, and can be regarded as an SU(2) gauge field4. The symmetry of the field is revealed in the optical spin Hall effect, where, under resonant excitation of the Dirac points, precession of the photon pseudospin around the field direction leads to the formation of two spin domains. Furthermore, we observe that the Dresselhaus-type field changes its sign in the same Dirac valley on switching from s to p bands, in good agreement with the tight-binding modelling. Our work demonstrating a non-Abelian gauge field for light on the microscale paves the way towards manipulation of photons via spin on a chip.Published versio

Dynamics of spin polarization in tilted polariton rings

This is an accepted manuscript of an article published by the American Physical Society in Physical Review B on 22/04/2021, available online: https://doi.org/10.1103/PhysRevB.103.165306 The accepted version of the publication may differ from the final published version.We have observed the effect of pseudomagnetic field originating from the polaritonic analog of spin-orbit coupling [transverse electric and transverse magnetic (TE-TM) splitting] on a polariton condensate in a ring-shaped microcavity. The effect gives rise to a stable four-leaf pattern around the ring as seen from the linear polarization measurements of the condensate photoluminescence. This pattern is found to originate from the interplay of the cavity potential, energy relaxation, and TE-TM splitting in the ring. Our observations are compared to the dissipative one-dimensional spinor Gross-Pitaevskii equation with the TE-TM splitting energy, which shows good qualitative agreement.Published versio

Exciton-polariton topological insulator

The authors thank R. Thomale for fruitful discussions. S.K. acknowledges the European Commission for the H2020 Marie Skłodowska-Curie Actions (MSCA) fellowship (Topopolis). S.K., S.H. and M.S. are grateful for financial support by the JMU-Technion seed money program. S.H. also acknowledges support by the EPSRC ”Hybrid Polaritonics” Grant (EP/M025330/1). The Würzburg group acknowledges support by the ImPACT Program, Japan Science and Technology Agency and the State of Bavaria. T.C.H.L. and R. G. were supported by the Ministry of Education (Singapore) Grant No. 2017-T2-1-001Topological insulators—materials that are insulating in the bulk but allow electrons to flow on their surface—are striking examples of materials in which topological invariants are manifested in robustness against perturbations such as defects and disorder1. Their most prominent feature is the emergence of edge states at the boundary between areas with different topological properties. The observable physical effect is unidirectional robust transport of these edge states. Topological insulators were originally observed in the integer quantum Hall effect2 (in which conductance is quantized in a strong magnetic field) and subsequently suggested3,4,5 and observed6 to exist without a magnetic field, by virtue of other effects such as strong spin–orbit interaction. These were systems of correlated electrons. During the past decade, the concepts of topological physics have been introduced into other fields, including microwaves7,8, photonic systems9,10, cold atoms11,12, acoustics13,14 and even mechanics15. Recently, topological insulators were suggested to be possible in exciton-polariton systems16,17,18 organized as honeycomb (graphene-like) lattices, under the influence of a magnetic field. Exciton-polaritons are part-light, part-matter quasiparticles that emerge from strong coupling of quantum-well excitons and cavity photons19. Accordingly, the predicted topological effects differ from all those demonstrated thus far. Here we demonstrate experimentally an exciton-polariton topological insulator. Our lattice of coupled semiconductor microcavities is excited non-resonantly by a laser, and an applied magnetic field leads to the unidirectional flow of a polariton wavepacket around the edge of the array. This chiral edge mode is populated by a polariton condensation mechanism. We use scanning imaging techniques in real space and Fourier space to measure photoluminescence and thus visualize the mode as it propagates. We demonstrate that the topological edge mode goes around defects, and that its propagation direction can be reversed by inverting the applied magnetic field. Our exciton-polariton topological insulator paves the way for topological phenomena that involve light–matter interaction, amplification and the interaction of exciton-polaritons as a nonlinear many-body system.PostprintPeer reviewe

Topological turbulence in spin-orbit-coupled driven-dissipative quantum fluids of light generates high-angular-momentum states

This is an accepted manuscript of an article published by IOP Publishing in EPL on 13/05/2021, available online: https://doi.org/10.1209/0295-5075/133/66001 The accepted version of the publication may differ from the final published version.We demonstrate the formation of a high-angular-momentum turbulent state in an exciton-polariton quantum fluid with TE-TM Spin-Orbit Coupling (SOC). The transfer of particles from quasi-resonantly cw pumped σ+ component to σ- component is accompanied with the generation of a turbulent gas of quantum vortices by inhomogeneities. We show that this system is unstable with respect to the formation of bogolons at a finite wave vector, controlled by the laser detuning. This instability can be triggered by an inhomogeneity of the pumping profile as in present calculations or by other sources like natural disorder in the cavity. In a finite-size cavity, the domains with this wave vector form a ring-like structure along the border of the cavity, with a gas of mostly same-sign vortices in the center. The total angular momentum is imposed by the sign of TE-TM SOC, the wave vector at which the instability develops, and the cavity size. This effect can be detected experimentally via local dispersion measurements or by interference. The proposed configuration thus allows simultaneous experimental studies of quantum turbulence and high-angular-momentum states in continuously pumped exciton-polariton condensates.We acknowledge the support of the projects EU Marie Curie "QUANTOPOL" (846353), "Quantum Fluids of Light" (ANR-16-CE30-0021), of the ANR Labex GaNEXT (ANR-11-LABX-0014), and of the ANR program "Investissements d'Avenir" through the IDEX-ISITE initiative 16-IDEX-0001 (CAP 20-25). SVK acknowledges the support from the Ministry of Education and Science of the Russian Federation (0791-2020-0006).Published versio