Thursday, September 10, 2015

Abstract-Strong-Coupled Collective Cyclotron Resonance and Terahertz Cavity Photon in 2D Electron Gases

September 16, 2015 4:00PM to 5:00PM
Qi Zhang, Rice University


Building 440, Room A105



Achieving strong light-matter interaction in low-dimensional solid state systems is essential for both fundamental studies and device applications of cavity quantum electrodynamics (QED). It is particularly interesting to understand and even control the dynamics of collective excitations in solid states, when they are strongly coupled to cavity photons. A Landau-quantized, high-mobility two-dimensional electron gas (2DEG) provides a uniquely clean and tunable semiconductor system in which to explore strong light-matter interaction with many-electron states. In this talk, I will first show how rapidly a superposition of massively degenerate Landau levels loses its coherence in the free space.
We observed a collective radiative decay, or superradiance, of cyclotron resonance (CR) in 2DEG with time-domain terahertz magneto-spectroscopy. In the second part, I will demonstrate the strong-coupling between the cyclotron resonance and THz cavity photons. We observed Rabi oscillation in time domain, as well as the collective vacuum Rabi splitting. We significantly suppressed the superradiance decay of CR by the high-Q THz cavity, and resolved an ultra-narrow intrinsic CR linewidth (5 GHz). Our method may also apply to various correlated 2D systems with collective THz excitations. It opens an access to the intriguing physics of THz many-body cavity-QED.

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