Optical characterization of the Si:Se+ spin-photon interface

The combination of both matter qubits and photonic qubits presents a very promising method for generating entanglement between qubits in order to scale up both quantum computing and quantum communication platforms. Hosting both qubits in silicon would be a favourable approach as silicon has not only the most mature microelectronics industry but also the most mature photonics industry. Singly ionized selenium donors (Si:Se+) have recently been identified as a possible candidate. Si:Se+ possess the excellent coherence lifetimes of conventional donor spin qubits in silicon but additionally has photonic access to the spin states at a convenient wavelength, 2.9 um. The spin-photon interface of Si:Se+ has the potential to be the basis for an integrated, all silicon, quantum computer. For this work we made custom samples with the specific purpose of measuring the crucial optical properties that determine the viability of the Si:Se+ spin-photon interface as a basis for a quantum architecture. We present photoluminescence, absorption, hole burning, and magnetic resonance experiments towards the characterization of the Si:Se+ spin-photon interface. We determined a transition dipole moment of 1.96 +- 0.08 Debye, a lower bound for the zero-phonon line fraction of > 15.1 +- 0.3 %, and a lower bound for the radiative efficiency of > 0.75 +- 0.08 %. Further results of the peak and area conversion factors and the dependence of peak energy and linewidth on electrically neutral impurities are also presented.