The latest and greatest in solid-state quantum emitters

In this talk, we present results from two different types of solid-state quantum emitters. The first part of the talk will focus on the greatest self-assembled InGaAs quantum dots (QDs). QDs have many advantages as light sources, such as their sharp emission linewidths, good single photon emission statistics and ability to be incorporated into solid-state devices. They also suffer from two major sources of noise: charge noise due to fluctuating trapped charges in the crystal, and nuclear spin noise due to the hyperfine interaction of electrons in the QD with a large number of nuclear spins, represented by a resultant fluctuating Overhauser field, which allows Raman scattering in the negative exciton system. This negatively affects the quality of emitted photons by reducing their indistinguishability. The application of a magnetic field in the growth direction screens the electron spin from the nuclear spins, resulting in a recovery of near-unity photon indistinguishability.

The 2nd part of the talk will focus on latest solid-state quantum emitters based on monolayer (1L) WSe2. We have taken a first step towards deterministic engineering of the emitter location and optical properties. We show that local strain gradients in the 2D crystal offer spatial and spectral isolation of non-classical light emitters and red-detune the emission energy of emitters up to ~170 meV. The strain gradients are provided by substrate patterning. With this technique, we have achieved a highly isolated emitter which demonstrated almost perfect anti-bunching. To exploit these emitters fully, the ability to precisely control their optical properties is needed. We achieve this via integrating the 1L WSe2 onto the piezoelectric actuator, which allows us an active tuning of the strain field and hence tuning of the optical properties.