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    Wavefunction of polariton condensates in a tunable acoustic lattice
    (Bristol : IOP, 2012) Cerda-Méndez, E.A.; Krizhanovskii, D.N.; Biermann, K.; Hey, R.; Skolnick, M.S.; Santos, P.V.
    We study the spatial coherence of polariton condensates subjected to coherent modulation by a one-dimensional tunable acoustic potential.We use an interferometric technique to measure the amplitude and phase of the macroscopic condensate wavefunction. By increasing the acoustic modulation amplitude, we track the transition from the extended wavefunction of the unperturbed condensate to a regime where the wavefunction is spatially modulated and then to a fully confined regime, where independent condensates form at the minima of the potential with negligible particle tunneling between adjacent sites.
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    Spatial self-organization of macroscopic quantum states of exciton-polaritons in acoustic lattices
    (Milton Park : Taylor & Francis, 2016) Buller, J.V.T.; Cerda-Méndez, E.A.; Balderas-Navarro, R.E.; Biermann, K.; Santos, P.V.
    Exciton-polariton systems can sustain macroscopic quantum states (MQSs) under a periodic potential modulation. In this paper, we investigate the structure of these states in acoustic square lattices by probing their wave functions in real and momentum spaces using spectral tomography. We show that the polariton MQSs, when excited by a Gaussian laser beam, self-organize in a concentric structure, consisting of a single, two-dimensional gap-soliton (GS) state surrounded by one dimensional (1D) MQSs with lower energy. The latter form at hyperbolical points of the modulated polariton dispersion. While the size of the GS tends to saturate with increasing particle density, the emission region of the surrounding 1D states increases. The existence of these MQSs in acoustic lattices is quantitatively supported by a theoretical model based on the variational solution of the Gross–Pitaevskii equation. The formation of the 1D states in a ring around the central GS is attributed to the energy gradient in this region, which reduces the overall symmetry of the lattice. The results broaden the experimental understanding of self-localized polariton states, which may prove relevant for functionalities exploiting solitonic objects.