The coherent manipulation of quantum states is a key area in solid-state physics. It involves powerful concepts, many developed in atomic physics and quantum optics, to advanced solid-state materials, notably semiconductors and superconductors. A clear advantage of the solid-state is the possibility of on-chip integration for applications in quantum sensing, quantum communication and quantum information processing. The solid-state environment is complex, in particular the processes by which information encoded in a single quantum state leaks to the environment.
Single photons play a crucial role in quantum science and technology: they provide presently the only way of interfacing remote quantum systems. Remarkably, arguably the best emitter of single photons at present is a single quantum dot, a semiconductor-based solid-state system: a single quantum dot is a fast, robust, narrow linewidth, highly antibunched source of single photons, properties not shared by any other emitter.
The radiative lifetime of a semiconductor quantum dot is typically around 1 ns. This defines a crucial time-scale: coherent manipulation has to be carried out on sub-ns time-scales. Coherence can be extended to longer times using a spin qubit. In this case, sub-ns manipulation remains crucial as it allows many gate operations to be carried out before coherence is lost.
The goal here is to set up new experimental hardware for manipulating quantum states in semiconductors on sub-ns time-scales. The hardware will produce and monitor ps laser pulses with both a duration and chirp tailored to particular applications. The immediate applications are in quantum imaging, single photon generation and rotations of single spins.