Group Seminar at MPQ and via Zoom: Color centers in silicon nanostructures at mK cryogenics

Laurits Piehorsch, University of Copenhagen
Group seminar at MPQ lecture hall and via Zoom
Thursday, September 24, 9:00 am (CEST)

Abstract:
Abstract: Photonic quantum computing with solid state spin registers presents a promising path to utility scale quantum computing. Compared to more mature quantum computing platforms, the investigation of optical spin-photon interfaces in the telecommunications band only started in the last decade. Color centers in silicon can be such interfaces. The T-center in particular emerged as a promising candidate due to its photon emission in the original telecommunications band and long spin coherence times. Initial characterizations were done at cryogenic temperatures as low as 1.2 K, including photoluminescence spectra at magnetic fields and coherence times. Even the entanglement of two separated T-centers has been demonstrated. To estimate resource requirements for a utility scale quantum computer based on color centers, it is crucial to compare the relevant noise processes in various temperature regimes. This talk covers the establishment of a dilution refrigerator with optical access, and measurements that probe and control solid state emitters at temperatures < 50 mK. First measurements on ensembles of T-centers demonstrate the successful set-up by probing the instantaneous homogeneous linewidth and initial spin control results. Additionally, a series of measurements at temperatures from 100 mK to 10 K reveals a phonon-mediated process, governing the effective decay rate. To motivate the pursuit of this platform as well as hardware choices, the presentation includes a brief review of current plans for how such a quantum computer could be constructed.