Photon Phase Shift at the Few-Photon Level and Optical Switching by a Quantum Dot in a Microcavity

Abstract

Quantum-dot-based nonlinearities are an important building block for logic operations in quantum information processing. The authors build on theoretical proposals by using the nonlinear effects of a spin-photon interaction and measuring the resultant phase shifts of scattered light pulses induced by a semiconductor quantum dot. Phase rotations of almost 80\ifmmode^\circ\else\textdegree\fi{} are achieved at the single-photon level, and phase switching is demonstrated. These findings highlight the importance of semiconductor quantum dots as a nonlinear medium for developing quantum information processing and quantum photonic integrated circuits.