Exciton–polariton condensates with flat bands in a two-dimensional kagome lattice

Masumoto, Naoyuki; Kim, Na Young; Byrnes, Tim; Kusudo, Kenichiro; Löffler, Andreas; Höfling, Sven; Forchel, A.; Yamamoto, Yoshihisa

doi:10.1088/1367-2630/14/6/065002

Cited by 113 publications

(108 citation statements)

References 18 publications

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“…In particular, a BEC of quasi-particle excitations in semiconductor systems consisting of exciton-polaritons have been observed [7,8]. Exciton-polariton BECs are formed in semiconductor microcavities [9], or planar dielectric Fabry-Pérot optical cavities [10], for example, and can be described as halfmatter, half-light excitations that are typically created using laser injection methods [11,12]. Exciton-polariton BECs are a non-equilibrium phenomenon that can be achieved at room temperatures for suitable materials that support the polaritons [13].…”

Section: Introductionmentioning

confidence: 99%

Sagnac interferometry with coherent vortex superposition states in exciton-polariton condensates

et al. 2016

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We investigate prospects of using counter-rotating vortex superposition states in non-equilibrium exciton-polariton Bose-Einstein condensates for the purposes of Sagnac interferometry. We first investigate the stability of vortex-antivortex superposition states, and show that they survive at steady-state in a variety of configurations. Counter-rotating vortex superpositions are of potential interest to gyroscope and seismometer applications for detecting rotations. Methods of improving the sensitivity are investigated by targeting high momentum states via metastable condensation, and the application of periodic lattices. The sensitivity of the polariton gyroscope is compared to its optical and atomic counterparts. Due to the large interferometer areas in optical systems and small de Broglie wavelengths for atomic BECs, the sensitivity per detected photon is found to be considerably less for the polariton gyroscope than with competing methods. However, polariton gyroscopes have an advantage over atomic BECs in a high signal-to-noise ratio, and have other practical advantages such as room-temperature operation and robust design. We estimate that the final sensitivities including signal-to-noise aspects are competitive with existing methods.

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Section: Introductionmentioning

confidence: 99%

Sagnac interferometry with coherent vortex superposition states in exciton-polariton condensates

et al. 2016

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“…[53], giving a topological gap of about 0.06 meV [32]. (b) Practical realization in semiconductor microcavities composed of distributed Bragg reflectors (DBRs) [45], with periodic potential V (x) induced, e.g., via metal surface patterning (other mechanisms are discussed in the text). (c) Realization of the effective potential V (x) in a nonlinear optical system, using coupled waveguides [55].…”

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confidence: 99%

Chiral Bogoliubov excitations in nonlinear bosonic systems

et al. 2016

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We present a versatile scheme for creating topological Bogoliubov excitations in weakly interacting bosonic systems. Our proposal relies on a background stationary field that consists of a kagome vortex lattice, which breaks time-reversal symmetry and induces a periodic potential for Bogoliubov excitations. In analogy to the Haldane model, no external magnetic field or net flux is required. We construct a generic model based on the two-dimensional nonlinear Schrödinger equation and demonstrate the emergence of topological gaps crossed by chiral Bogoliubov edge modes. Our scheme can be realized in a wide variety of physical systems ranging from nonlinear optical systems to exciton-polariton condensates. DOI: 10.1103/PhysRevB.93.020502 Introduction. The quantum Hall effect is one of the most celebrated results of modern condensed matter physics [1]. The robustness of the Hall conductance can be traced back to the nontrivial topology of the underlying electronic band structure [2], which ensures the existence of chiral edge states and thus eliminates backscattering. Recently there was a surge of interest in the possibility to exploit such topology to create chiral bosonic modes in driven-dissipative systemswith possible applications to one-way transport of photons [3][4][5][6][7][8][9][10][11][12][13], polaritons [14][15][16], excitons [16,17], magnons [18,19], and phonons [20,21]. A common thread through these seemingly diverse ideas has been to induce topology by external manipulations of a single-particle band structure, with interactions playing a negligible role. Exceptions from this noninteracting paradigm are proposals that combine strong interactions with externally induced artificial gauge fields to create nonequilibrium analogs of bosonic fractional quantum Hall states [22][23][24][25].Here, we take a new perspective and consider (bosonic) Bogoliubov excitations ("Bogoliubons") where weak interactions induce a nontrivial topology [26]. We demonstrate that topological Bogoliubons naturally occur on top of a condensate that exhibits a lattice of vortex-antivortex pairs, with no net flux required. Interactions are key to harness the time-reversal (TR) symmetry breaking induced by the condensate vortices. From the viewpoint of Bogoliubov excitations, they generate nontrivial "hopping" phases which lead to an analog of the Haldane lattice model [27]. The corresponding lattice can be defined by a periodic potential introduced either externally or via interactions with the condensate.Although our scheme can be applied to any system described by a two-dimensional (2D) nonlinear Schrödinger equation (Gross-Pitaevskii equation or analog thereof), our analysis focuses on systems of weakly interacting bosons that have a light component, where the required vortex lattice can readily be obtained from the interference of several coherent optical fields (see Fig. 1). In this setting, the phase-imprinting mechanism allowing for nontrivial topology is analogous to that proposed a few years ago in the context of optomech...

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“…In particular, flatband (FB) lattices, existing due to specific local symmetries, provide the framework supporting completely dispersionless bands in the system's spectrum [1]. FB lattices have been realized in photonic waveguide arrays [2], exciton-polariton condensates [3], and atomic Bose-Einstein condensates (BECs) [4]. FB lattices are characterized by the existence of compact localized states (CLSs), which, being FB eigenstates, have nonzero amplitudes only on a finite number of sites [1].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear localized flat-band modes with spin-orbit coupling

et al. 2016

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We report the coexistence and properties of stable compact localized states (CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flatband network with spin-orbit coupling (SOC). The system can be implemented by means of a binary Bose-Einstein condensate loaded in the corresponding optical lattice. In the linear limit, the SOC opens a minigap between flat and dispersive bands in the system's bandgap structure, and preserves the existence of CLSs at the flatband frequency, simultaneously lowering their symmetry. Adding onsite cubic nonlinearity, the CLSs persist and remain available in an exact analytical form, with frequencies which are smoothly tuned into the minigap. Inside of the minigap, the CLS and DS families are stable in narrow areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and DSs are stable too.

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Exciton–polariton condensates with flat bands in a two-dimensional kagome lattice

Cited by 113 publications

References 18 publications

Sagnac interferometry with coherent vortex superposition states in exciton-polariton condensates

Sagnac interferometry with coherent vortex superposition states in exciton-polariton condensates

Chiral Bogoliubov excitations in nonlinear bosonic systems

Nonlinear localized flat-band modes with spin-orbit coupling

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