分类： 光学 >> 量子光学 提交时间： 2023-02-19
Wei Liu
Yi-Tao Wang
Zhi-Peng Li
Shang Yu
Zhi-Jin Ke
Yu Meng
Jian-Shun Tang
Chuan-Feng Li
Guang-Can Guo
摘要： Quantum emitters in van der Waals (vdW) materials have attracted lots of attentions in recent years, and shown great potentials to be fabricated as quantum photonic nanodevices. Especially, the single photon emitter (SPE) in hexagonal boron nitride (hBN) emerges with the outstanding room-temperature quantum performances, whereas the ubiquitous blinking and bleaching restrict its practical applications and investigations critically. The blister in vdW materials possessing stable structure can modify the local bandgap by strains on nanoscale, which is supposed to have the ability to fix this photostability problem. Here we report a blister-induced high-purity SPE in hBN under ambient conditions showing stable quantum-emitting performances, and no evidence of blinking and bleaching for one year. Remarkably, we observe the nontrivial successive activating and quenching dynamical process of the fluorescent defects at the SPE region under low pressures for the first time, and the robust recoverability of the SPE after turning back to the atmospheric pressure. The pressure-tuned performance indicates the SPE origins from the lattice defect isolated and activated by the strain induced from the blister, and sheds lights on the future high-performance quantum sources based on hBN.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Zheng-Hao Liu
Yu Meng
Yu-Ze Wu
Ze-Yan Hao
Zhen-Peng Xu
Cheng-Jun Ai
Hai Wei
Kai Wen
Jing-Ling Chen
Jie Ma
Jin-Shi Xu
Chuan-Feng Li
Guang-Can Guo
摘要： Contextuality, a hallmark feature of the quantum theory, captures the incompatibility between quantum correlations and any noncontextual hidden-variable model. The Greenberger--Horne--Zeilinger (GHZ)-type paradoxes are proofs of contextuality which reveal this incompatibility with deterministic logical arguments. However, the simplest GHZ-type paradox with the fewest number of complete contexts and the largest degree of nonclassicality remains elusive. Here, we derive a GHZ-type paradox utilising only three complete contexts and show this number cannot be further reduced. We forward to demonstrating the paradox with an experiment which recovered all essential ingredients in a 37-dimensional contextuality test based on high-speed modulation, optical convolution and homodyne detection of time-multiplexed modes of coherent light that can be interpreted as a classical entity. By proposing and observing a strong form of contextuality in an extremely high-dimensional system, our results pave the way for the exploration of exotic quantum correlations with optical systems.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yuan-Ze Yang
Tian-Xiang Zhu
Zhi-Peng Li
Xiao-Dong Zeng
Nai-Jie Guo
Shang Yu
Yu Meng
Zhao-An Wang
Lin-Ke Xie
Zong-Quan Zhou
Qiang Li
Jin-Shi Xu
Wei Liu
Yi-Tao Wang
Jian-Shun Tang
Chuan-Feng Li
Guang-Can Guo
摘要： Optically addressable spins in two-dimensional hexagonal boron nitride (hBN) attract widespread attention for their potential advantage in on-chip quantum devices, such as quantum sensors and quantum network. A variety of spin defects have been found in hBN, but no convenient and deterministic generation methods have been reported for other defects except negatively charged boron vacancy ($\rm V_B^-$). Here we report that by using femtosecond laser direct writing technology, we can deterministically create spin defect ensembles with spectra range from 550 nm to 800 nm. Positive single-peak optically detected magnetic resonance (ODMR) signals are detected in the presence of longitudinal magnetic field, and the contrast can reach 0.8%. With the appropriate thickness of hBN flakes and femtosecond laser pulse energy, we can deterministically generate bright spin defects in-situ. Our results provide a convenient deterministic method to create spin defects in hBN, which will motivate more endeavors for future researches and applications of spin-based technologies.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Nai-Jie Guo
Yuan-Ze Yang
Xiao-Dong Zeng
Shang Yu
Yu Meng
Zhi-Peng Li
Zhao-An Wang
Lin-Ke Xie
Jin-Shi Xu
Jun-Feng Wang
Qiang Li
Wei Liu
Yi-Tao Wang
Jian-Shun Tang
Chuan-Feng Li
Guang-Can Guo
摘要： Optically addressable spin defects in solid-state materials are the promising platform for quantum information applications, such as quantum network. The two-dimensional (2D) hexagonal boron nitride (hBN) as a carrier of abundant defects is an emerging candidate. While negatively charged boron vacancy (V$_\text{B}^-$) spin defect in hBN is studied intensively, the coherent control of single spin in 2D materials has not been realized yet, which constitutes the cornerstone for applying the 2D spin defect in quantum-information tasks. Here, we report the first coherent control of the single electronic spin in 2D materials at room temperature. Considering both the optical and spin properties, this defect belongs to a new type of spin defects distinguished to all other spin defects observed before. This defect has simultaneously the narrow zero-phonon line, high Debye-Waller factor, high brightness, high polarization of PL photons, low $ g^{(2)}(0) $, moderate spin $ T_{1} $ and $ T_{2} $ comparable to V$ _\text{B}^{-} $. These excellent optical properties and relatively good spin properties of this single spin lay the foundation for the applications of the 2D-material-hosted spin defects in quantum information tasks.
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