分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The realization of all-optical integration and optical computing has always been our goal. One of the most significant challenges is to make integrated all-optical logic devices as small as possible. Here, we report the implementation of ultra-compact all-optical logic devices and integrated chips on silicon photonic platforms by topology optimization. The footprint for the fabricated all-optical logic gates with XOR and OR functions is only 1.3*1.3 {\mu}m2 (~0.84{\lambda}*0.84{\lambda}), that are the smallest all-optical dielectric logic devices ever verified in experiments in the optical communication range. The ultra-low loss of the optical signal is also demonstrated experimentally (-0.96dB). Furthermore, an integrated chip containing seven major logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) and a half adder is fabricated, where the associated footprint is only 1.3*4.5 {\mu}m2. Our work opens up a new path towards practical all-optical integration and optical computing.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Xin Xie
Jianchen Dang
Sai Yan
Weixuan Zhang
Huiming Hao
Shan Xiao
Shushu Shi
Zhanchun Zuo
Haiqiao Ni
Zhichuan Niu
Xiangdong Zhang
Can Wang
Xiulai Xu
摘要： The second-order topological photonic crystal with 0D corner state provides a new way to investigate cavity quantum electrodynamics and develop topological nanophotonic devices with diverse functionalities. Here, we report on the optimization and robustness of topological corner state in the second-order topological photonic crystal both in theory and in experiment. The topological nanocavity is formed based on the 2D generalized Su-Schrieffer-Heeger model. The quality factor of corner state is optimized theoretically and experimentally by changing the gap between two photonic crystals or just modulating the position or size of the airholes surrounding the corner. The fabricated quality factors are further optimized by the surface passivation treatment which reduces surface absorption. A maximum quality factor of the fabricated devices is about 6000, which is the highest value ever reported for the active topological corner state. Furthermore, we demonstrate the robustness of corner state against strong disorders including the bulk defect, edge defect, and even corner defect. Our results lay a solid foundation for the further investigations and applications of the topological corner state, such as the investigation of strong coupling regime and the development of optical devices for topological nanophotonic circuitry.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Integrated quantum memories are a scalable solution to synchronize a large number of quantum computers, which are essential to build a quantum network to boost their capabilities on information processing. Rather than expecting to find a specific kind of atoms to meet all the requirements of a good quantum memory, as other protocols usually do, we propose that assigning the memory requirements on coherence property and control property to rare earth ions and lithium niobate crystal, respectively. In particular, optical quantum states are stored into erbium doped lithium niobate (Er$^{3+}$:LiNbO$_3$) micro-cavity by utilizing the electro-optic effect of LiNbO$_3$. The Er$^{3+}$:LiNbO$_3$ cavity frequency can be shifted by an external electric field, which is used to control the photon-echo emission by changing the resonance condition between micro-cavity and collective atomic excitation. According to calculations, high efficiency and low noise storage can be achieved. Benefiting from the host lithium-niobate thin film, such a device can be controlled by on-chip electrodes and is easy to be integrated with modern photonic devices, paving way of integrated quantum chips.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： As an important imaging technique, holography has been realized with different physical dimensions of light,including polarization, wavelength, and time. Recently, quantum holography has been realized by utilizing polarization entangled state with the advantages of high robustness and enhanced spatial resolution, comparing with classical one. However, the polarization is only a two-dimensional degree of freedom, which greatly limits the capacity of quantum holography. Here, we propose a method to realize high-dimensional quantum holography by using high-dimensional orbital angular momentum (OAM) entanglement. A high capacity OAM-encoded quantum holographic system can be obtained by multiplexing a wide range of OAM-dependent holographic images. Proof-of-principle experiments with four- and six-dimensional OAM entangled states have been implemented and verify the feasibility of our idea. Our experimental results also demonstrate that the high-dimensional quantum holography shows a high robustness to classical noise. Furthermore, OAMselective holographic scheme for quantum encryption is proposed and demonstrated. Comparing with the previous schemes, the level of security of holographic imaging encryption system can be greatly improved in our high-dimensional quantum holography.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Ling-Jun Kong
Weixuan Zhang
Peng
Li
Xuyue Guo
Jingfeng Zhang
Furong Zhang
Jianlin Zhao
Xiangdong Zhang
摘要： Optical knots and links have attracted great attention because of their exotic topological characteristics. Recent investigations have shown that the information encoding based on optical knots could possess robust features against external perturbations. However, as a superior coding scheme, it is also necessary to achieve a high capacity, which is hard to be fulfilled by existing knot-carriers owing to the limit number of associated topological invariants. Thus, how to realize the knot-based information coding with a high capacity is a key problem to be solved. Here, we create a type of nested vortex knot, and show that it can be used to fulfill the robust information coding with a high capacity assisted by a large number of intrinsic topological invariants. In experiments, we design and fabricate metasurface holograms to generate light fields sustaining different kinds of nested vortex links. Furthermore, we verify the feasibility of the high-capacity coding scheme based on those topological optical knots. Our work opens another way to realize the robust and high capacity optical coding, which may have useful impacts on the field of information transfer and storage.
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