Ultrafast Control and Rabi Oscillations of Polaritons

Abstract

We report the experimental observation and control of space and time-resolved light-matter Rabi oscillations in a microcavity. Our setup precision and the system coherence are so high that coherent control can be implemented with amplification or switching off of the oscillations and even erasing of the polariton density by optical pulses. The data are reproduced by a quantum optical model with excellent accuracy, providing new insights on the key components that rule the polariton dynamics. DOI: 10.1103/PhysRevLett.113.226401 PACS numbers: 71.36.+c, 78.47.JRabi oscillations [1] are the embodiment of quantum interactions: when a mode a is excited and is coupled to a second mode b, the excitation is transferred from a to b and when the symmetric situation is established, the excitation comes back in a cyclical unitary flow. When this occurs at the single particle level between two-level systems, it provides the ground for qubits [2], which, if they can be further manipulated, opens the possibility to perform quantum information processing [3]. Such an oscillation is of probability amplitudes and therefore is a strongly quantum mechanical phenomenon, that involves maximally entangled statesThe same physics also holds, not at the quantum level, but with coherent states of the fields, a situation known in the literature as implementing an "optical atom" [4] or a "classical two-level system" [5]. The oscillation is then more properly qualified as "normal mode coupling" [6,7] as it is now between the fields themselves,rather than their probability amplitudes. The denomination of Rabi oscillations remains, however, popular also in this case [8,9]. While of limited value for hardcore implementation of quantum information processing, it is desirable for fundamental purposes and semiclassical applications to have access to such classical qubits, or "cebits" [10]. In particular, they can help to explore the origin and mechanism of nonlocality and parallelization in genuinely quantum systems . While Rabi oscillations are at the heart of polariton physics, they are so fast in a typical microcavity-in the subpicosecond time range-that they are typically glossed over and the macroscopic physics of polaritons investigated in their coarse graining. Pioneering attempts to observe them showed the inherent difficulty and reported hardly two oscillations with 3 orders of magnitude loss of contrast each time [29], attributed to the inhomogeneous broadening of excitons by the theory [30], which could provide a qualitative agreement only. Later reports through pump-probe techniques [31][32][33], in particular, in conjunction with an applied magnetic field [34], increased their visibility but remained tightly constrained to their bare observation. Since polaritons are increasingly addressed at the single particle level [35,36], it becomes capital to harness their Rabi dynamics [37]. In this Letter, thanks to significant progress in both the quality of the structures (the sample description is given in the Supplemental Material [38]) ...

Oscillatory dynamics of nonequilibrium dissipative exciton-polariton condensates in weak-contrast lattices

“…The influence of Josephson effect occurring in the nonlinear regime on polarization dynamics and spontaneous spatial separation of exciton-polariton condensates with opposite polarization has been predicted 47 . At present, the main discussion is focused on the possibility of time enhancement of coherent oscillations occurring in coupled exciton-photon condensate system [48][49][50] . It has been proposed that long-lived oscillations could be obtained essentially due to open character of excitonpolariton systems and interaction with pumped reservoir.…”

Macroscopic Two-Dimensional Polariton Condensates

“…This is the paradigm of microcavity exciton-polaritons: quasiparticles created by the strong coupling between the photonic mode of a microcavity and the excitonic transition of semiconductor quantum wells [2]. Polaritons manifest their composite nature with a combination of photonic and excitonic properties [3]. Thanks to their photonic component, polaritons can ballistically propagate in the plane of the microcavity with velocities up to a few percent of the speed of light [4].…”

Self-Interfering Wave Packets

“…In most of these cases, interactions bring the physics to even farther extents rather than spoiling the underlying linear effect, that remains nevertheless the one capturing the phenomenon. The linear regime can be achieved at low densities [30] since the polariton interaction at the few particles level is small. In this case, the dynamics of the wavefunction |ψ is ruled by the polariton propagator Π such that |ψ(t) = Π(t − t 0 )|ψ(t 0 ) .…”