Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots

TL;DR

This paper introduces a method to precisely control photon echo timing in quantum dots by using a resonant control pulse, enabling delays or advances of several picoseconds, which is crucial for quantum information applications.

Contribution

The study presents a novel control protocol using a resonant 2pi pulse to manipulate photon echo timing in quantum dots, enhancing temporal precision in quantum coherence control.

Findings

Photon echo emission time can be retarded or advanced by 5 ps.

Control pulses can significantly extend temporal shifts beyond 5 ps.

The method is demonstrated on (In,Ga)As quantum dots.

Abstract

Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a novel concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2pi area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.