Polaritonic Cross Feshbach Resonance Navadeh-Toupchi, M; Takemura, N; Anderson, M D ...
Physical review letters,
2019-Feb-01, Letnik:
122, Številka:
4
Journal Article
Recenzirano
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We demonstrate the existence of a cross Feshbach resonance by strongly driving a lower polariton mode and by monitoring in time the transmission of a short optical pulse at the energy of the upper ...polariton mode in a semiconductor microcavity. From the signatures of the optical resonance, strength, and sign of the energy shift, we attribute the origin of the scattering process between polariton modes with opposite circular polarization to a biexciton bound state. From this study, we infer the conditions required for a strong enhancement of the generation of entangled photon pairs.
Non-linear interactions in coherent gases are not only at the origin of bright and dark solitons and superfluids; they also give rise to phenomena such as multistability, which hold great promise for ...the development of advanced photonic and spintronic devices. In particular, spinor multistability in strongly coupled semiconductor microcavities shows that the spin of hundreds of exciton-polaritons can be coherently controlled, opening the route to spin-optronic devices such as ultrafast spin memories, gates or even neuronal communication schemes. Here we demonstrate that switching between the stable spin states of a driven polariton gas can be controlled by ultrafast optical pulses. Although such a long-lived spin memory necessarily relies on strong and anisotropic spinor interactions within the coherent polariton gas, we also highlight the crucial role of non-linear losses and formation of a non-radiative particle reservoir for ultrafast spin switching.
Using an angle-resolved heterodyne four-wave-mixing technique, we probe the low momentum excitation spectrum of a coherent polariton gas. The experimental results are well captured by the Bogoliubov ...transformation which describes the transition from single particle excitations of a normal fluid to soundlike excitations of a superfluid. In a dense coherent polariton gas, we find all the characteristics of a Bogoliubov transformation, i.e., the positive and negative energy branch with respect to the polariton gas energy at rest, soundlike shapes for the excitations dispersion, intensity, and linewidth ratio between the two branches in agreement with the theory. The influence of the nonequilibrium character of the polariton gas is shown by a careful analysis of its dispersion.
A Feshbach resonance occurs when the energy of two interacting free particles comes into resonance with a molecular bound state. When approaching this resonance, marked changes in the interaction ...strength between the particles can arise. Feshbach resonances provide a powerful tool for controlling the interactions in ultracold atomic gases, which can be switched from repulsive to attractive1, 2, 3, 4, and have allowed a range of many-body quantum physics effects to be explored5, 6. Here we demonstrate a Feshbach resonance based on the polariton spinor interactions in a semiconductor microcavity. By tuning the energy of two polaritons with anti-parallel spins across the biexciton bound state energy, we show an enhancement of attractive interactions and a prompt change to repulsive interactions. A mean-field two-channel model quantitatively reproduces the experimental results. This observation paves the way for a new tool for tuning polariton interactions and to move forward into quantum correlated polariton physics.
We investigate polariton-polariton interactions in a semiconductor microcavity through two-dimensional Fourier transform (2DFT) spectroscopy. We observe, in addition to the lower-lower and the ...upper-upper polariton self-interactions, a lower-upper cross interaction. This appears as separated peaks in the on-diagonal and off-diagonal parts of 2DFT spectra. Moreover, we elucidate the role of the polariton dispersion through a fine structure in the 2DFT spectrum. Simulations, based on lower-upper polariton basis Gross-Pitaevskii equations including both self-and cross interactions, result in a 2DFT spectra in qualitative agreement with experiments.
We report the first observation of stochastic resonance in confined exciton polaritons. We evidence this phenomena by tracking the polaritons behavior through two stochastic resonance quantifiers ...namely the spectral magnification factor and the signal-to-noise ratio. The evolution of the stochastic resonance in the function of the modulation amplitude of the periodic excitation signal is studied. Our experimental observations are well reproduced by numerical simulations performed in the framework of the Gross-Pitaevskii equation under stochastic perturbation.
Using femtosecond pump-probe spectroscopy, we identify excitation-induced dephasing as a major mechanism responsible for the breakdown of the strong coupling between excitons and photons in a ...semiconductor microcavity. The effects of dephasing are observed on the transmitted probe-pulse spectrum as a density-dependent broadening of the exciton-polariton resonances and the emergence of a third resonance at high excitation density. A striking asymmetry in the energy shift between the upper and the lower polaritons is also evidenced. Using the excitonic Bloch equations, we quantify the respective contributions to the energy shift of many-body effects associated with Coulomb fermion exchange and photon assisted exchange processes and the contribution to collisional broadening.
We present the results of a detailed time-resolved luminescence study carried out on a very high quality InGaAs quantum well sample where the contributions at the energy of the exciton and at the ...band edge can be clearly separated. We perform this experiment with a spectral resolution and a sensitivity of the setup, allowing us to keep the observation of these two separate contributions over a broad range of times and densities. This allows us to directly evidence the exciton formation time, which depends on the density as expected from theory. We also denote the dominant contribution of excitons to the luminescence signal, and the lack of thermodynamical equilibrium at low densities.
We report on the effect of noise on the characteristics of the bistable polariton emission system. The present experiment provides a time-resolved access to the polariton emission intensity. We ...evidence the noise-induced transitions between the two stable states of the bistable polaritons. It is shown that the external noise specifications, intensity and correlation time, can efficiently modify the polariton Kramers time and residence time. We find that there is a threshold noise strength that provokes the collapse of the hysteresis loop. The experimental results are reproduced by numerical simulations using Gross-Pitaevskii equation driven by a stochastic excitation.
We report on noise-induced spin ordering in a collective quasiparticle system: spinor stochastic resonance. Synergetic interplay of a polarization-modulated signal and a polarization noise allows us ...to switch coherently between the two metastable states of a microcavity-polariton spin bistable system. Spinor stochastic resonance is demonstrated in a zero-dimensional GaAs based microcavity. The resonance behaviors of both the spin amplification and the signal-to-noise ratio are experimentally evidenced as a function of the noise strength for different amplitude modulations. They are theoretically reproduced using a spinor Gross-Pitaevskii equation driven by a randomly polarized laser field.
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