Quantum interference of identical photons from remote GaAs quantum dots
No TL;DR found
Abstract
Photonic quantum technology provides a viable route to quantum communication<sup>1,2</sup>, quantum simulation<sup>3</sup> and quantum information processing<sup>4</sup>. Recent progress has seen the realization of boson sampling using 20 single photons<sup>3</sup> and quantum key distribution over hundreds of kilometres<sup>2</sup>. Scaling the complexity requires architectures containing multiple photon sources, photon counters and a large number of indistinguishable single photons. Semiconductor quantum dots are bright and fast sources of coherent single photons<sup>5-9</sup>. For applications, a roadblock is the poor quantum coherence on interfering single photons created by independent quantum dots<sup>10,11</sup>. Here we demonstrate two-photon interference with near-unity visibility (93.0 ± 0.8)% using photons from two completely separate GaAs quantum dots. The experiment retains all the emission into the zero phonon line-only the weak phonon sideband is rejected; temporal post-selection is not employed. By exploiting quantum interference, we demonstrate a photonic controlled-not circuit and an entanglement with fidelity of (85.0 ± 1.0)% between photons of different origins. The two-photon interference visibility is high enough that the entanglement fidelity is well above the classical threshold. The high mutual coherence of the photons stems from high-quality materials, diode structure and relatively large quantum dot size. Our results establish a platform-GaAs quantum dots-for creating coherent single photons in a scalable way.