The most challenging problem in the application of quantum information in the future is the detection and manipulation of single quantum states. This is because quantum states are very fragile. Once integrated into the external environment, their quantum properties are easily destroyed. S. Haroche and D. Wineland made groundbreaking work in the measurement and manipulation of a single photon state by trapping a single atom in a microwave cavity and capturing charged ions by a potential trap, and won the 2012 Nobel Prize in Physics. The quantum interference experiment technology they used became the main method of quantum optics research. How to realize quantum coherent manipulation in solid-state systems is the key and focus of future quantum network and quantum computing applications.
Recently, Phys. Rew. Lett. (109, 267402, 2012) reported on the photons based on the solid state quantum system of InAs quantum dots developed by the Institute of Semiconductors of the Chinese Academy of Sciences and the University of South Florida and the University of Texas at Austin. Important progress in interference research: the quantum interference phenomenon of single-photon and two-photon was observed in semiconductor InAs self-organized quantum dots simultaneously, and the effect of spectral dispersion on interference contrast was studied.
The Institute of New Semiconductor Optoelectronic Materials and Quantum Information of the Institute of Semiconductors has carried out research on InAs / GaAs self-organized quantum dot materials and single photon emission devices in recent years, breaking through the problem of controlled molecular beam epitaxial growth of low-density quantum dots and mastering the distribution The key technology of the design growth and process preparation of the structure of the coupled Bragg microcavity and quantum dots, the single photon emitting device working at the temperature of liquid nitrogen was developed. In 2011, in collaboration with the above-mentioned American research group, in the study of the correlation between the photon scattering field and the field, photon and photon of two InAs single quantum dots with a space of 40um, it was found that the single photons emitted by the quantum dots at low temperature are coherent Scattering (interference visibility up to 20%). Since the photons emitted by two different quantum dots are indistinguishable, two-photon interference with interference visibility up to 40% is also observed.
The significance of this work lies in the realization of a two-photon interference without independent tuning of the spectral resonance of the quantum system. By exploring the space to completely separate the photon coherence of InAs quantum dots, the sensitivity of quantum dots to the solid-state environment can be evaluated. If we can eliminate or avoid this external average effect of multiple random vibration detuning of quantum dots caused by spectral dispersion, the single-photon coherence will be greatly increased, such as replacing the intrinsic excitation with a three-particle state transition The transition of sub-state can realize long-distance entanglement of single spin and so on. This is of great significance for the future realization of quantum coherent manipulation of solid-state systems based on semiconductor quantum dots.
This research was supported by the National Natural Science Foundation of China.
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