Arka Majundar, Stanford University
Abstract
Quantum dots coupled to photonic crystal cavities constitute a scalable, robust, on‐chip, semiconductor platform for probing fundamental cavity quantum electrodynamics. Very strong interaction between light and matter can be achieved in this system as a result of the field localization inside sub‐cubic wavelength volumes leading to vacuum Rabi frequencies in the range of 10s of GHz. This strong light‐ matter interaction produces an optical nonlinearity that is present even at single‐photon level and is tunable at a very fast time‐scale. In this talk, I will describe several experiments focusing on the fundamental physics of this coupled system, as well as on proof‐of‐principle demonstrations of low‐ power optical information processing.
First, I will describe the effect of photon blockade and photon‐induced tunneling, which demonstrate the quantum nature of the coupled dot‐cavity system. Using these effects and the photon correlation measurements of light transmitted through the dot‐cavity system, we identify the first and second order energy manifolds resulting from the strong coupling between the quantum dot and the cavity field [1]. Following this, I will show how the interaction of the quantum dot with its semiconductor environment gives rise to novel phenomena unique to a solid state cavity QED system, namely off‐resonant dot‐cavity coupling. We use this effect to implement a cavity‐assisted resonant quantum dot spectroscopy method [2], which allows us to resolve frequency features far below the limit of a conventional spectrometer. Lastly, I will demonstrate some applications of this coupled dot‐cavity system for performing optical information processing, namely all‐optical switching and electro‐optic switching. With the light‐matter interactions controlled at the most fundamental level; these nano‐photonic devices operate at extremely low control powers and can achieve switching speeds potentially exceeding 10GHz [3].