Optically modulated magnetic resonance of erbium implanted silicon.

Er implanted Si is a candidate for quantum and photonic applications; however, several different Er centres are generated, and their symmetry, energy level structure, magnetic and optical properties, and mutual interactions have been poorly understood, which has been a major barrier to the development of these applications. Optically modulated magnetic resonance (OMMR) gives a spectrum of the modulation of an electron paramagnetic resonance (EPR) signal by a tuneable optical field. Our OMMR spectrum of Er implanted Si agrees with three independent measurements, showing that we have made the first measurement of the crystal field splitting of the I manifold of Er implanted Si, and allows us to revise the crystal field splitting of the I manifold. This splitting originates from a photoluminescence (PL) active O coordinated Er centre with orthorhombic C symmetry, which neighbours an EPR active O coordinated Er centre with monoclinic C symmetry. This pair of centres could form the basis of a controlled NOT (CNOT) gate.