An apparatus for optical illumination of semiconductor spin qubits with spatiotemporal beam control

Optical illumination of semiconductor spin qubit devices affects trapped charges in the substrate, with implications ranging from homogenizing turn-on voltages to effects on charge noise and qubit decoherence. Previous studies have relied on flooded illumination of the whole device by an LED. We present an apparatus, operable at millikelvin temperatures, for studying the effect of optical illumination on semiconductor spin qubits, using a pulsed beam that can be steered across the whole sample surface, which enables more precise control over charge in the substrate. Our aim is a greater understanding and control of disorder's effects on the qubit system.