Magnetic field control of photon echo in the electron-trion system: Shuffling of coherences between optically accessible and inaccessible states

TL;DR

This paper demonstrates how magnetic fields can manipulate photon echo signals in a semiconductor quantum well by controlling electron spin coherences, revealing potential for quantum information applications.

Contribution

It introduces a method to control photon echo signals via magnetic fields by shuffling coherences between optically accessible and inaccessible states in a semiconductor system.

Findings

Photon echo amplitude can be tuned from maximum to zero.

Magnetic field induces oscillations in the photon echo signal.

Theoretical model explains the spin-dependent control of coherences.

Abstract

We report on magnetic field induced oscillations of the photon echo signal from negatively charged excitons in a CdTe/(Cd,Mg)Te semiconductor quantum well. The oscillatory signal is due to Larmor precession of the electron spin about a transverse magnetic field and depends sensitively on the polarization configuration of the exciting and refocusing pulses. The echo amplitude can be fully tuned from maximum down to zero depending on the time delay between the two pulses and the magnetic field strength. The results are explained in terms of the optical Bloch equations accounting for the spin level structure of electron and trion.