Meta-cavity Quantum Electrodynamics

Abstract

Cavity quantum electrodynamics (cQED) harnesses light-matter interactions to produce nonclassical light states. However, a fundamental challenge lies in simultaneously achieving Purcell enhancement and tailored wavefront control within a single cavity, due to conflicting resonator requirements. Here, we overcome this limitation by demonstrating triggered single-photon emission with customizable wavefronts from semiconductor quantum dots embedded in geometric-phase metacavities. These monolithic devices - only 200 nm thick - deliver Purcell-enhanced emission alongside spin-momentum-locked radiation, vortex beams, and holographic patterns. The meta-atom lattice provides high-Q optical confinement, while spatially modulated orientations enable efficient outcoupling of photons with designed states. This work establishes a new paradigm for intrinsically multiplexing metasurface-based wavefront shaping with cQED, enabling high-performance quantum light sources from subwavelength-scale monolithic platforms.

Figures (4)

• Figure 1: Working principles of the quantum electrodynamics in a GP meta-cavity. (a) Schematic of the monolithic meta-cavity. (b) Roadmap of the meta-cavity. Left panel: A typical first-order circular Bragg cavity. Middle panel: A typical GP meta-surface. Right panel: A meta-cavity. (c) Top-view of the meta-cavity. QD is placed in the center of the cavity. (d) A typical simulated Purcell factor and radiation efficiency for a meta-cavity. (e) GP $\varphi_g$ obtained from orientations $\theta_g$ of the elliptical meta-atoms in the cladding region.
• Figure 2: The properties in the meta-cavities. (a, b) Simulated near-field intensity distribution of the unperturbed mode (a, $\delta = 0$, $P = 208nm$, $D = 92nm$, $R_c = 0.48\times2P$) and perturbed mode (b, $\delta = 0.2$, $P = 208nm$, $D = 92nm$, $R_c = 0.48\times2P$). Top panel: White dash line represents the near-field position. (c, d) K-space distribution from simulation and experiment for the unperturbed (c) and perturbed (d) modes, where $k_0$ represents NA = 1. The experimental NA is 0.65. (e, f) The SEM images of the meta-cavities, where the meta-atoms are circular (e) and elliptical air holes (f), respectively.
• Figure 3: Experimental characterizations of the meta-cavity single-photon source. (a) Photoluminescent spectra showing the QD emission (red) spectrally detuned by 0.4nm from the meta-cavity resonance mode (blue). Inset: Coherent Rabi oscillations. (b) Radiative lifetime of the QD. The green curve indicates the instrument response function (IRF). (c) HBT coincidence histogram of single photons. (d) HOM interference histogram of single photons.
• Figure 4: Experimental demonstrations of photon's spatial state manipulation in GP meta-cavities. (a-c) The color-code in-plane orientations $\theta_g(x,y)$ of elliptical meta-atoms. The insets are the k-space radiation patterns with light cone marked by white circle. (d) The spin-momentum-locked radiation $|k_{\sigma +}\rangle = (-0.31, 0)$, $|k_{\sigma -}\rangle = (+0.32, 0)$. (e) The OAM emission pattern. (f) The reconstructed hologram of a "+" pattern. (g) The far-field patterns and (h) histogram after phase projection to a series of vortex wave plates with different topological charges of $\ell$.