Decoherence of donors in silicon at millikelvin temperatures*

Donors in silicon are model spin systems [1] and potential candidates for implementing solid-state quantum bits. In that perspective, a detailed understanding of their coherence properties is needed. I will present measurements of Bismuth donors spin relaxation and coherence times at millikelvin temperatures obtained with a home-made spectrometer working at the quantum limit of sensitivity based on superconducting micro-resonators and Josephson parametric amplifiers [2], and I will discuss the various mechanisms at play.
[1] G. Feher, Phys. Rev. 114, 1219 (1959)
[2] A. Bienfait et al., Nature Nanotechnology 11, 253 (2016)