Tunable quantum dots in monolithic Fabry-Perot microcavities for high-performance single-photon sources

Cavity-enhanced single quantum dots(QDs)are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies.Nevertheless,harnessing the Purcell effect requires precise spectral and spatial alignment of the QDs’emission with the cavity mode,which is challenging for most cavities.Here we have successfully integrated miniaturized Fabry-Perot microcavities with a piezoelectric actuator,and demonstrated a bright single-photon source derived from a deterministically coupled QD within this microcavity.Leveraging the cavity-membrane structures,we have achieved large spectral tunability via strain tuning.On resonance,a high Purcell factor of~9 is attained.The source delivers single photons with simultaneous high extraction efficiency of 0.58,high purity of 0.956(2)and high indistinguishability of 0.922(4).Together with its compact footprint,our scheme facilitates the scalable integration of indistinguishable quantum light sources on-chip,therefore removing a major barrier to the development of solid-state quantum information platforms based on QDs.

Generalized Kibble-Zurek mechanism for defects formation in trapped ions

The Kibble-Zurek(KZ)mechanism has played a fundamental role in defect formation with universal scaling laws in nonequilibrium phase transitions.However,this theory may not accurately predict the scaling laws in inhomogeneous systems and slow quenching processes.Here,we present a generalized KZ mechanism for the defect formation in trapped ions with the freeze-out condition gt=b0τ(t),where g is a universal quenching velocity function and b0 is a constant.We derived a differential equationφ(x,t)to account for the frozen correlation length of a kink in an inhomogeneous system and demonstrated a smooth crossover from a fast quenching process to a slow quenching process,which agrees well with the experiments performed by Ulm et al.[Nat.Commun.4,2290(2013)]and Pyka et al.[Nat.Commun.4,2291(2013)].Furthermore,we confirmed our theoretical model using molecular dynamics simulation by solving the stochastic differential equation,showing excellent agreement with the results from the differential equation.Our theory provides a general theoretical framework for studying KZ physics in inhomogeneous systems,which has applications in other nonequilibrium platforms studied experimentally.

Optimization of parameters of a surface-electrode ion trap and experimental study of influences of surface on ion lifetime

In this paper we report the optimal design and fabrication of a gold-on-silica linear segmented surface-electrode ion trap. By optimizing the thickness and width of the electrodes, we improved the trapping ability and trap scalability. By using some practical experimental operation methods, we successfully minimized the trap heating rate. Consequently, we could trap a string of up to 38 ions, and a zigzag structure with 24 ions, and transport two trapped ions to different zones. We also studied the influences of the ion chip surface on the ion lifetime. The excellent trapping ability and flexibility of operation of the planar ion trap shows that it has high feasibility for application in the development a practical quantum information processor or quantum simulator.