Ultrafast Control and Rabi Oscillations of Polaritons

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.

Figure 1

(a) Oscillations observed experimentally in the cavity field and reproduced theoretically in both the cavity and exciton fields. (b) The lower (LP) and upper (UP) polaritons excited by a Gaussian pulse which overlap with the branches determine the effective state created in the system. (c) The dynamics can be reduced to that of $|⟨a(t)⟩{|}^2$ alone and described quantitatively by the theory.

Figure 2

Various states created in the system by varying the pulse energy and their evolution on the Bloch sphere, showing the systematic relaxation towards the LP. In the inset, the full exciton-photon dynamics are reconstructed theoretically for the case ${\omega }_{\mathrm{L}}=833\mathrm{nm}$ (photon in red, exciton in blue) and variations (showing the envelope of the oscillations only) when removing the effect of the exciton reservoir (I, black dashed), removing the effect of polariton dephasing (II, dotted-dashed yellow) or, on the opposite, enhancing the effect of the reservoir (III, long-dashed blue). $P_{\exp }$ and ${\gamma }_{\exp }$ are the fitted values for the experiment.

Figure 3

(a) Succession of various dynamical evolutions in time of the photon (dashed yellow) and the exciton (green) complex amplitudes (here with fixed modulus) that can be passed from one to the other with an appropriate pulse excitation. Normal mode-coupling features a $\pi /2$ dephasing in both time and optical phase and oscillate radially while polaritons oscillate circularly. Furthermore, they oscillate jointly and with ($\pi$ out of phase with each other and against) the rotating frame in the case of a UP (LP). (b)–(d) Experimental realization (points) and theoretical fit (solid curve) of three two-pulses excitation, showing (b) amplification, (c) transition from an exciton-photon Rabi oscillation to a LP, and (d) field annihilation.