Hybrid acousto-optical swing-up preparation of exciton and biexciton states in a quantum dot

Recent years brought the idea of hybrid systems, in which quantum degrees of freedom, due to controlled couplings, allow the transfer of quantum information and may lead to the emergence of new generation devices. Due to the universal coupling with all solid-state systems and compatibility with miniaturization, acoustic fields will play an important role in interfacing such components. Optically active quantum dots (QDs) are at the forefront of systems for applications in quantum technologies and their multiple available interfaces make them a great component of hybrid systems. QDs generate polarization-entangled photon pairs, however deterministic and high-fidelity preparation of the state is needed. All resonant schemes need filtering to distinguish emitted photons from the excitation pulse, which limits the photon yield significantly. Thus, non-resonant excitation methods are needed like the recently proposed and successful swing-up scheme. Here, we propose a hybrid acousto-optical version of this non-resonant scheme to prepare exciton and biexciton states. We show that using acoustic modulation allows selectively exciting either exciton or biexciton states with just one mode of vibration and one optical pulse or vice versa: acoustic pulse during detuned optical driving. Thus, either of the fields can act as a trigger controlling the evolution. Further, we evaluate the impact of phonon decoherence at finite temperatures for two types of application-relevant QDs, InAs/GaAs and GaAs/AlGaAs, and find that for GaAs QDs exciton preparation can be almost decoherence-free even at liquid nitrogen temperatures already with currently available acoustic modulation frequencies. This approach may pave the way for generating entanglement between an emitter and a quantum acoustic mode when using the acoustic mode as a trigger for the transitions.