CAS Academicain PAN Jianwei and Prof.LU Chaoyang in School of Physical Sciences have succeeded in realizing high quality single-photon source based on semiconductor quantum dots. This exciting result, which is the first Nature article in quantum dots and quantum optics by Chinese researchers, was published in Nature Nanotechnology on Feb. 4th.
Quantum dot is a typical nanocrystal prepared through MBE method and can act as realistic single-photon source for quantum communication and optical quantum computing. Previous work based on non-resonant excitation cannot be further applied to scalable quantum information processing, due to dephasing caused by uncontrolled emission time jitter and homo-generous broadening of the excited state.
A prerequisite for practical and reliable optical quantum information technology is high quality single-photon source with a high level of efficiency and indistinguishability. PAN and LU first applied resonant optical excitation with picosecond laser pulse to significantly eliminate the dephasing effects and generate near background-free (~99.7%purity) and highly indistinguishable single photons. They observed non-postselective HOM interference with a raw visibility of 0.91(2) and corrected visibility of 0.97(2) for two resonance fluorescence photons excited by two successive p pulses separated by 2ns. These parameters push the research in China stand among the best in the related fields and lay the foundation of scalable optical quantum computing and solid state platform.
(TU lijie, USTC News Center, Hefei National Lab of Physical Sciences at the Microscale)