Observation of large spontaneous emission rate enhancement of quantum dots in a broken-symmetry slow-light waveguide

Abstract

Quantum states of light and matter can be manipulated on the nanoscale to provide a technological resource for aiding the implementation of scalable photonic quantum technologies. Experimental progress relies on the quality and efficiency of the coupling between photons and internal spin states of quantum emitters. Here we demonstrate a nanophotonic waveguide platform with embedded quantum dots (QDs) that enables both Purcell-enhanced emission and strong chiral coupling. The design uses slow-light effects in a glide-plane photonic crystal waveguide with QD tuning to match the emission frequency to the slow-light region. Simulations were used to map the chirality and Purcell enhancement depending on the position of a dipole emitter relative to the air holes. The highest Purcell factors and chirality occur in separate regions, but there is still a significant area where high values of both can be obtained. Based on this, we first demonstrate a record large radiative decay rate of 17 ± 2 ns−1 (60 ± 6 ps lifetime) corresponding to a 20 ± 2 fold Purcell enhancement. This was achieved by electric-field tuning of the QD to the slow-light region and quasi-resonant phonon-side band excitation. We then demonstrate a 5 ± 1 fold Purcell enhancement for a dot with high degree of chiral coupling to waveguide modes, substantially surpassing all previous measurements. Together these demonstrate the excellent prospects for using QDs in scalable implementations of on-chip spin-photonics relying on chiral quantum optics.

Systematic design of a robust half-W1 photonic crystal waveguide for interfacing slow light and trapped cold atoms

“…Other waveguides combining chiral and strong coupling to emitters exist, however with a common hurdle in maximizing and overlapping spatially both features [62,63]. In our case, this overlap is readily excellent, due to the absence of symmetry protection from chirality and to the limited spatial structure of the mode (see figure 4(b)), from which both chirality and Purcell factor inherit.…”

Ultrafast and Bright Quantum Emitters from the Cavity-Coupled Single Perovskite Nanocrystals

“…However, the Purcell enhancement value reported in this study may not accurately represent the true enhancement owing to the relaxation time from the higher states to the lowest exciton state. 33 , 34 Consequently, the measured Purcell enhancement factor can be increased through quasi-resonant excitation or resonant excitation because direct pumping to a near-ground exciton state or ground exciton state reduces the relaxation time, which can be beneficial for achieving a true Purcell-enhanced emission rate. Furthermore, this moderate Purcell enhancement may originate from the slight difference between the positions of the perovskite NC and the cavity mode as the perovskite NCs are randomly distributed.…”

Revealing the Invisible: Imaging Through Non-Radiating Subspace

“…Inverse problems in electromagnetics, encompassing inverse source [1,2], inverse scattering [3][4][5][6], inverse design [7], and inverse synthesis [8] problems, have found widespread applications in various fields, including microwave imaging [9], radar tracking [10], breast cancer detecting [11], remote sensing [12], tomography [13], seismology [14], failure analysis [15], nondestructive evaluation [16], antenna design and pattern synthesis [17,18], nanoscale optical positioning [19], and integrated quantum photonics [20][21][22]. Among these, electromagnetic inverse scattering focuses on detecting, locating, shape finding, and material imaging of unknown objects using scattered fields and Maxwell's equations.…”