Ultrafast Room-Temperature Single Photon Emission from Quantum Dots Coupled to Plasmonic Nanocavities

TLDR

Efficient and bright single‑photon sources at room temperature are essential for quantum information systems, yet the intrinsic radiative lifetime of quantum emitters (~10 ns) limits emission rates. The study demonstrates ultrafast (~10 ps) spontaneous emission from a single quantum emitter coupled to a plasmonic nanocavity at room temperature. The plasmonic nanocavity is coupled to a single colloidal semiconductor quantum dot and functions as an efficient optical antenna that directs emission into a single lobe normal to the surface. The nanocavity integration yields a 540‑fold reduction in emission lifetime and a 1900‑fold increase in total emission intensity, enabling directional room‑temperature single‑photon emission rates exceeding 80 GHz for various quantum emitters.

Abstract

Efficient and bright single photon sources at room temperature are critical components for quantum information systems such as quantum key distribution, quantum state teleportation, and quantum computation. However, the intrinsic radiative lifetime of quantum emitters is typically ∼10 ns, which severely limits the maximum single photon emission rate and thus entanglement rates. Here, we demonstrate the regime of ultrafast spontaneous emission (∼10 ps) from a single quantum emitter coupled to a plasmonic nanocavity at room temperature. The nanocavity integrated with a single colloidal semiconductor quantum dot produces a 540-fold decrease in the emission lifetime and a simultaneous 1900-fold increase in the total emission intensity. At the same time, the nanocavity acts as a highly efficient optical antenna directing the emission into a single lobe normal to the surface. This plasmonic platform is a versatile geometry into which a variety of other quantum emitters, such as crystal color centers, can be integrated for directional, room-temperature single photon emission rates exceeding 80 GHz.