We study analytically and numerically the dynamics of the quantum non-stationary system composed of a two-level atom interacting with a single mode cavity field whose frequency is rapidly modulated in time (with a small amplitude). We identify modulation laws resulting in qualitatively different dynamical regimes and we present analytical solutions in some simple cases. In particular, we analyse minutely the influence of the field-atom coupling on the photon generation from vacuum via the dynamical Casimir effect.

We develop an efficient back gate for silicon-on-insulator (SOI) devices operating at cryogenic temperatures, and measure the quadratic hyperfine Stark shift parameter of arsenic donors in isotopically purified 28 Si-SOI layers using such structures. The back gate is implemented using MeV ion implantation through the SOI layer forming a metallic electrode in the handle wafer, enabling large and uniform electric fields up to ∼ 2 V/µm to be applied across the SOI layer. Utilizing this structure we measure the Stark shift parameters of arsenic donors embedded in the 28 Si SOI layer and find a contact hyperfine Stark parameter of η a = −1.9 ± 0.2 × 10 −3 µm 2 /V 2 . We also demonstrate electric-field driven dopant ionization in the SOI device layer, measured by electron spin resonance.

Selenium impurities in silicon are deep double donors and their optical and electronic properties have been recently investigated due to their application for infrared detection. However, a singlyionised selenium donor (Se + ) possesses an electron spin which makes it a potential candidate as a silicon-based spin qubit, with significant potential advantages compared to the more commonly studied group V donors. Here we study the electron spin relaxation (T1) and coherence (T2) times of Se + in isotopically purified 28-silicon, and find them to be up to two orders of magnitude longer than shallow group V donors at temperatures above ∼ 15 K. We further study the dynamics of donor-acceptor recombination between selenium and boron, demonstrating that it is possible to control the donor charge state through optical excitation of neutral Se 0 .