Macroscopic coherence of semiconductor quantum dots and its application to quantum information technology

Yanwen Wu, Xiaoqin Li, Duncan G. Steel +2 more

T. Takagahara

We discuss the Rabi splitting and Rabi oscillation of excitons in semiconductor quantum dots and clarify the fundamental physics and new characteristic features. These coherent optical phenomena are not restricted to semiconductor quantum dots and the predicted features would be observed also in atoms and molecules. The universality of the phenomena ensures the possibility for application to quantum state control and quantum information processing by optical means. We discuss briefly the mechanisms of exciton dephasing in semiconductor quantum dots in conjunction with recent observations of the lifetime-limited exciton dephasing time and show that the pure dephasing rate is very small but is not vanishing even at zero Kelvin.

K. Berrada

Giorgio Nicolí, Michael S. Ferguson, Clemens Rössler +7 more

Scalable architectures for quantum information technologies require one to selectively couple long-distance qubits while suppressing environmental noise and cross talk. In semiconductor materials, the coherent coupling of a single spin on a quantum dot to a cavity hosting fermionic modes offers a new solution to this technological challenge. Here, we demonstrate coherent coupling between two spatially separated quantum dots using an electronic cavity design that takes advantage of whispering-gallery modes in a two-dimensional electron gas. The cavity-mediated, long-distance coupling effectively minimizes undesirable direct cross talk between the dots and defines a scalable architecture for all-electronic semiconductor-based quantum information processing.

Huan Song, Tatsuya Usuki

D. V. Averin, B. Ruggiero, P. Silvestrini