Towards a global quantum network: Photoelectron trapping in double quantum dots

While the journey from today's fledgling quantum computers to a global quantum information network may seem daunting, researchers are continually, and at an accelerating pace, making progress towards that goal. One key element essential to that progress is the transfer of quantum information between single photons and solid-state quanta – and the properties of semiconductor quantum dots (QDs) make them excellent candidates for photon-electron quantum coupling. One historical stumbling block has been that although quantum circuits require nondestructive transfer between separate dots, using single QDs usually fails due to destructive transfer in which photoelectrons are immediately lost upon measurement.

Recently, however, scientists at The University of Tokyo, Princeton University, Ruhr-Universität Bochum, and RIKEN found that nondestructive measurement is feasible using gallium arsenide double quantum dots (DQDs), thereby taking a significant step towards long distance entanglement distribution. Moreover, the importance of using a lateral dot is that these have a possibility to store and manipulate the photoelectrons – and while previous studies show detection of photocurrents or photoelectron signals, the scientists state that to their knowledge, none of them performed experiments demonstrating the possibility of further photoelectron storage or manipulation. Lastly, although the researchers have not yet demonstrated the spin manipulation of photoelectrons, their double dot structure shows repetitive tunneling of single photoelectrons, and so satisfies the photoelectron spin manipulation condition.