We discuss a technique to manipulate and read out strictly resonantly excited exciton polaritons confined in a three-dimensional trap. The polaritons are trapped via their photonic part in a locally elongated microcavity with a high quality factor (Q ∼ 6000), giving rise to sharp zero-dimensional resonances. Manipulation of the polaritons is achieved by spectrally tuning the quantum well excitons via the quantum confined Stark effect up to 10 meV, while the signal of the resonantly excited polaritons is simultaneously read out via the photocurrent flowing through the device. The effects of polariton-polariton interactions and interactions with the environment are revealed in the zero detuning regime by excitation power dependent investigations. By increasing the polariton number in our trap via resonant optical injection, we observe a pronounced blueshift of the lower polariton eigenenergy towards the weakly coupled cavity resonance. Furthermore, the photocurrent exhibits pronounced nonlinearities when self-tuned into resonance via its excitation dependent spectral blueshift. Exciton polaritons are fascinating bosonic quasiparticles, arising from the strong coupling between quantum well (QW) excitons and photons confined in a semiconductor microcavity. They are extremely appealing for studying the fundamentals of bosonic physics, such as Bose-Einstein condensation related effects, even at very high temperatures (up to 300 K) [1][2][3][4][5][6][7][8]. Moreover, polaritons have also been proposed to be promising candidates for the generation of single and indistinguishable photons on demand, when they are strongly confined in zerodimensional structures [9,10]. To date, most compact sources of single, indistinguishable photons are based on single quantum dots (QDs) integrated in tailored photonic environments [11]. While those systems have been optimized with respect to their efficiencies and photon interference visibilities, a fully scalable production of such devices is still a challenge due to the commonly applied randomized QD growth techniques. In contrast to semiconductor QD-microcavity systems, a polaritonic single photon source would ideally not suffer from very strong inhomogeneous broadening effects and hence could clearly outperform these existing systems in the sense of scalable realization. This would be highly beneficial for linear optics quantum information processing [12]. Indeed, the experimental realization of a system that exhibits polariton blockade (and hence generates polariton number states) would put a large number of goals in the emerging field of solid state based quantum emulation within reach. For instance, reaching the Mott insulator phase of a bosonic system, which is a key requirement to simulate quantum phase transitions [13], strongly relies on the abovementioned effects.Unfortunately, the prerequisites on the system for the observation of the required polariton quantum blockade effect are rather demanding, and conclusively the demonstration is still elusive.One important challenge ...

The development of high quality factor solid-state microcavities with low mode volumes has paved the way towards on-chip cavity quantum electrodynamics experiments and the development of high-performance nanophotonic devices. Here, we report on the implementation of a new kind of solid-state vertical microcavity, which allows for confinement of the electromagnetic field in the lateral direction without deep etching. The confinement originates from a local elongation of the cavity layer imprinted in a shallow etch and epitaxial overgrowth technique. We show that it is possible to improve the quality factor of such microcavities by a specific in-plane bullseye geometry consisting of a set of concentric rings with subwavelength dimensions. This design results in a smooth effective lateral photonic potential and therefore in a reduction of lateral scattering losses, which makes it highly appealing for experiments in the framework of exciton-polariton physics demanding tight spatial confinement.