The research team is made up of professor Qihuang Gong, associate professor Ying Gu and graduates from PKU. The researchers from Shanxi University and école Polytechnique Fédérale de Lausanne (EPFL) of Switzerland also contributed to the research findings.

The development of nanotechnology has enabled the study of interaction between photon and matter at nanoscale to be current focus in research, which is highly important for miniaturization of device in information technology. In the past few years, surface plasmon due to the collective electron oscillation in nanoscale metal has attracted great attention.

Based on the anisotropic Purcell factor induced by surface plasmon of metallic nanostructure and quantum interference principle, this study proposes a mechanism for controlling the spectrum width of spontaneous emission of atom with four energy levels. The key findings include spectral line width narrowing close to metallic nanowires, spectrum width variation (pulse) for periodic metallic nanostructures and dramatic change of spectrum in resonant metallic nanostructure. This study has potential applications in ultracompact functional quantum devices.

"This is a popular and active research direction at this moment”, according to the reviewer, "The paper bridges the fields of quantum optics and plasmonics that is useful for the field of nanostructures.”

This work was supported by the National Natural Science Foundation of China, the National Basic Research Program of China (973 Program) and State Key Laboratory for Mesoscopic Physics.