All-round Single-photon Source Realized by USTC


LU Chaoyang and PAN Jianwei group from USTC realized the first single-photon source that combines near perfect single-photon purity, indistinguishability and high extraction efficiency, opening the way to scalable multi photon quantum information experiment with solid-state platforms. On January, the study was published in Physical Review Letters and briefly introduced by American Physical Society Site. 

Single-photon devices that deterministically emit one and only one photon at a time are central resources for scalable photonic quantum technologies. It is crucial that the single-photon source simultaneously possesses purity (the sources must emit one and only one photon at a time), indistinguishability (all photons must be identical, for instance, in frequency and polarization) and efficiency—along sought-after goal in quantum photonics. However these three features have never been achieved simultaneously in a single device. 

Self-assembled quantum dots (QDs) have been shown to possess the highest quantum efficiency in all solid-state single-photon devices. In 2013 Pan’s group successfully developed single-photon device with very high purity and indistinguishability by resonant excitation of QDs, but the efficiency was low. In the present scheme, Pan and his colleagues are exploiting the so-called Purcell effect to enhance the emission rate of the quantum dot by embedding it in a micropillar cavity whose resonant frequency matches that of the dot. They realized a high-performance single-photon source that simultaneously achieves a generation efficiency of 96%, single photon purity of 99.1%, and in distinguish ability of 98.6% -- the best single-photon device ever developed.

Compared with heralded single photons produced by parametric down conversion,this single-photon source is superior, as it is ten times brighter, near perfectly pure and in distinguishable,and requires a pump power that is 7 orders of magnitude lower. The study was termed as tour-de-force by the reviewers and highlighted by Nature journal. It also attracted much attention from the industry for its potential commercial value.

The work was supported by the National Natural Science Foundation of China, the Chinese Academy ofSciences, and the National Fundamental Research Program.