分类： 光学 >> 量子光学 提交时间： 2023-02-19
Xiaodong Zheng
Peiyu Zhang
Renyou Ge
Liangliang Lu
Guanglong He
Qi Chen
Fangchao Qu
Labao Zhang
Xinlun Cai
Yanqing Lu
Shining Zhu
Peiheng Wu
Xiao-Song Ma
摘要： Integrated photonics provides a route both to miniaturize quantum key distribution (QKD) devices and to enhance their performance. A key element for achieving discrete-variable QKD is a single-photon detector. It is highly desirable to integrate detectors onto a photonic chip to enable the realization of practical and scalable quantum networks. We realize an integrated heterogeneous superconducting-silicon-photonic chip. Harnessing the unique high-speed feature of our optical waveguide-integrated superconducting detector, we perform the first optimal Bell-state measurement (BSM) of time-bin encoded qubits generated from two independent lasers. The optimal BSM enables an increased key rate of measurement-device-independent QKD, which is immune to all attacks against the detection system, and hence provides the basis for a QKD network with untrusted relays. Together with the time-multiplexed technique, we have enhanced the sifted key rate by almost one order of magnitude. With a 125 MHz clock rate, we obtain a secure key rate of 6.166 kbps over 24.0 dB loss, which is comparable to the state-of-the-art MDI-QKD experimental results with GHz clock rate. Combined with integrated QKD transmitters, a scalable, chip-based and cost-effective QKD network should become realizable in the near future.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The past decade has witnessed a booming development of topological photonics, which revolutionizes the methodology for controlling the behavior of light. A gigantic achievement is to engineer robust confined modes localized at interfaces between topologically distinct regions, where the optical context can trigger exotic topological phenomena exclusive to photons. Here, we provide an experimentally flexible approach to engineering topologically induced interface states in the visible regime via a unique design of complex superlattice formed by connecting two component superlattices of distinguished topological phases. Assisted by the intrinsic pseudospin degree due to the splitting between TM and TE polarized modes, we attain a precise manipulation of the spin-dependent topological interface states that can manifest themselves straightforwardly through transmission spectra. More specifically, since these topological localized modes stem from the hybridization of artificial photonic orbitals that are of topological origin as well, they are deemed as a novel topological effect and thus named as the secondary topological interface states. Our work develops an innovative and productive strategy to tune topologically protected localized modes, based on which various applications such as selective local enhancement can be exploited.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The past decade has seen a proliferation of topological materials for both insulators and semimetals in electronic systems and classical waves. Topological semimetals exhibit topologically protected band degeneracies, such as nodal points and nodal lines. Dirac nodal line semimetals (DNLS), which own four-fold line degeneracy, have drawn particular attention. DNLSs have been studied in electronic systems but there is no photonic DNLS. Here in this work, we provide a new mechanism which is unique for photonic systems to investigate a stringent photonic DNLS. When truncated, the photonic DNLS exhibits double-bowl states (DBS), which comprises two sets of perpendicularly polarized surface states. In sharp contrast to nondegenerate surface states in other photonic systems, here the two sets of surface states are almost degenerate over the whole spectrum range. The DBS and the bulk Dirac nodal ring (DNR) dispersion along the relevant directions, are experimentally resolved.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： High-dimensional entanglement is significant for the fundamental studies of quantum physics and offers unique advantages in various quantum information processing (QIP) tasks. Integrated quantum devices have recently emerged as a promising platform for creating, processing, and detecting complex high-dimensional entangled states. A crucial step towards practical quantum technologies is to verify that these devices work reliably with an optimal strategy. In this work, we experimentally implement an optimal quantum verification strategy on a three-dimensional maximally entangled state using local projective measurements on a silicon photonic chip. A 95% confidence is achieved from 1190 copies to verify the target quantum state. The obtained scaling of infidelity as a function of the number of copies is -0.5497+-0.0002, exceeding the standard quantum limit of -0.5 with 248 standard deviations. Our results indicate that quantum state verification could serve as an efficient tool for complex quantum measurement tasks.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this study, we propose and experimentally demonstrate a novel kind of Tamm plasmon topological superlattice (TTS) by engineering Tamm photonic crystals (TPCs) belonging to a different class of topology. Utilizing specifically designed double-layer metasurfaces etching on planar multilayered photonic structures, the TPC that supports the Tamm plasmon photonic bandgap is realized in the visible regime. Through the coupling of topological interface states existing between different TPCs, hybrid topological interface states of Tamm plasmon, called supermodes, are obtained that can be fully described by a tight-binding model. Meanwhile, we can achieve a tunable bandwidth of supermodes via varying the etching depth difference between double-layer metasurfaces. We show that the bandwidth decreases with the increase of etching depth difference, resulting in a nearly flat dispersion of supermodes with strong localization regardless of excitation angles. All the results are experimentally verified by measuring angular-resolved reflectance spectra. The TTS and supermodes proposed here open a new pathway for the manipulation of Tamm plasmons, based on which various promising applications such as integrated photonic devices, optical sensing, and enhancing light-matter interactions can be realized.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Optical frequency combs in microresonators (microcombs) have a wide range of applications in science and technology, due to its compact size and access to considerably larger comb spacing. Despite recent successes, the problems of self-starting, high mode efficiency as well as high output power have not been fully addressed for conventional soliton microcombs. Recent demonstration of laser cavity soliton microcombs by nesting a microresonator into a fiber cavity, shows great potential to solve the problems. Here we comprehensively study the dissipative soliton generation and interaction dynamics in a microresonator-filtered fiber laser in both theory and experiment. We first bring theoretical insight into the mode-locking principle, discuss the parameters effect on soliton properties and provide experimental guidelines for broadband soliton generation. We predict chirped bright dissipative soliton with flat-top spectral envelope in microresonators with normal dispersion, which is fundamentally infeasible for externally driven case. Furthermore, we experimentally achieve soliton microcombs with large bandwidth of ~10 nm and high mode efficiency of 90.7%. Finally, by taking advantage of an ultrahigh-speed time magnifier, we study the real-time soliton formation and interaction dynamics and experimentally observe soliton Newton's cradle. Our study will benefit the design of the novel, high-efficiency and self-starting microcombs for real-world applications.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Stimulated Brillouin scattering (SBS) in low-power and compact microresonators has created a new field in cavity nonlinear photonics due to the marriage between acoustic and optical signal processing. Considering the fundamental differences between backward SBS and forward SBS processes, it is challenging to observe the coexistence of both processes in the same microresonator, as well as the photon noise suppression for the forward stimulated Brillouin laser (FSBL). In this paper, we demonstrate the first 20-dB-noise-squeezed FSBL generation excited by the coexisting backward SBL (BSBL) in an ultrahigh-quality-factor Fabry-Perot (FP) microresonator based on multimode fiber (MMF). Multiple FSBLs and BSBLs are cascaded by multiple intermodal SBS processes in the multimode microresonator, where the cascaded process between backward SBS and forward SBS process (pump-BSBL-FSBL) provides a route towards additional noise squeezing, rendering the FSBL phase noise to be -120 dBc/Hz at 1 MHz offset frequency. Furthermore, we demonstrate the first Brillouin-Kerr soliton from a high-order BSBL, which also coexists with FSBLs. Our experimental results show the potential of MMF FP microresonator as an ideal testbed for high-dimensional nonlinear cavity dynamics and laser source with ultrahigh coherence.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Dissipative Kerr soliton (DKS) microcomb has emerged as an enabling technology that revolutionizes a wide range of applications in both basic science and technological innovation. Reliable turnkey operation with sub-opticalcycle and sub-femtosecond timing jitter is key to the success of many intriguing microcomb applications at the intersection of ultrafast optics and microwave electronics. Here we propose a novel approach to demonstrate the first turnkey Brillouin-DKS frequency comb. Our approach with a Chimera cavity offers essential benefits that are not attainable previously, including phase insensitivity, self-healing capability, deterministic selection of DKS state, and access to the ultralow noise comb state. The demonstrated turnkey Brillouin-DKS frequency comb achieves a fundamental comb linewidth of 100 mHz and DKS timing jitter of 1 femtosecond for averaging times up to 56 {\mu}s. The approach is universal and generalizable to various device platforms for user-friendly and field-deployable comb devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： How to utilize topological microcavities to control quantum emission is one of the ongoing research topics in the optical community. In this work, we investigate the emission of quantum emitters in doubly-resonant topological Tamm microcavity, which can simultaneously achieve dual resonances at two arbitrary wavelengths according to the needs of practical application. To achieve the enhancement of quantum emission in such cavities, we have exploited the tunable doubly-resonant modes, in which one of resonant modes corresponds to the pump laser wavelength and the other one is located at the emission wavelength of quantum emitters. Both theoretical and experimental results demonstrate that the pump excitation and emission efficiencies of quantum emitters are greatly enhanced. The main physical mechanism can be explained by the doubly-resonant cavity temporal coupled-mode theory. Furthermore, we observe the faster emission rate and the higher efficiency of unidirectional quantum emission, which have promising applications in optical detection, sensing, filtering, and light-emitting devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Ming-Hao Jiang
Wenyi Xue
Qian He
Yu-Yang An
Xiaodong Zheng
Wen-Jie Xu
Wenjun Wen
Yu-Bo Xie
Yanqing Lu
Shining Zhu
Xiao-Song Ma
摘要： The quantum internet -- in synergy with the internet that we use today -- promises an enabling platform for next-generation information processing, including exponentially speed-up distributed computation, secure communication, and high-precision metrology. The key ingredients for realizing such a global network are the distribution and storage of quantum entanglement. As quantum networks are likely to be based on existing fibre networks, telecom-wavelength entangled photons and corresponding quantum memories are of central interest. Recently, ${\rm ^{167}Er^{3+}}$ ions have been identified as a promising candidate for an efficient, broadband quantum memory at telecom wavelength. However, to date, no storage of entangled photons, the crucial step of quantum memory using these ions, has been reported. Here, we demonstrate the storage and recall of the entangled state of two telecom photons generated from an integrated photonic chip based on silicon nitride. Combining the natural narrow linewidth of the entangled photons and long storage time of ${\rm ^{167}Er^{3+}}$ ions, we achieve storage time of 400 ns, more than one order of magnitude longer than in previous works. Successful storage of entanglement in the crystal is certified by a violation of an entanglement witness by more than 12 standard deviations (-0.161 $\pm$ 0.012) at 400 ns storage time. These results pave the way for realizing quantum networks based on solid-state devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： One of the most fascinating aspects of quantum fields in curved spacetime is the Unruh effect. The direct experimental detection of Unruh temperature has remained an elusive challenge up to now. Gradient optical waveguides manipulating the dispersion of photons are assumed to realize the great acceleration of effective particles, leading to a high effective Unruh temperature. However, experimentally achieving this optical waveguide has not yet been reported. In this work, we exploit a tapered fiber to simulate the accelerated motion of effective particles and obtain an effective Unruh temperature. When light propagating in a tapered fiber is affected by the external high refractive index medium, a leaky phenomenon akin to bremsstrahlung will be observed, and the pattern of leaky radiation is dependent on the acceleration of photons. During the experiments, different accelerations corresponding to different Unruh temperatures are achieved by controlling the shape of the tapered waveguide.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The interference of quanta lies at the heart of quantum physics. The multipartite generalization of single-quanta interference creates entanglement, the coherent superposition of states shared by several quanta. Entanglement allows non-local correlations between many quanta and hence is a key resource for quantum information technology. Entanglement is typically considered to be essential for creating non-local correlations, manifested by multipartite interference. Here, we show that this is not the case and demonstrate multiphoton non-local quantum interference without entanglement of any intrinsic properties of the photons. We harness the superposition of the physical origin of a four-photon product state, which leads to constructive and destructive interference of the photons' mere existence. With the intrinsic indistinguishability in the generation process of photons, we realize four-photon frustrated quantum interference. We furthermore establish non-local control of multipartite quantum interference, in which we tune the phase of one undetected photon and observe the interference of the other three photons. Our work paves the way for fundamental studies of non-locality and potential applications in quantum technologies.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Wenjun Wen
Zhiyu Chen
Liangliang Lu
Wenhan Yan
Wenyi Xue
Peiyu Zhang
Yanqing Lu
Shining Zhu
Xiao-song Ma
摘要： Quantum network facilitates the secure transmission of information between different users. Establishing communication links among multiple users in a scalable and efficient way is important for realizing a large-scale quantum network. Here we develop an energy-time entanglement-based dense wavelength division multiplexed network based on an integrated silicon nitride micro-ring resonator, which offers a wide frequency span (covering at least the entire C-band) and narrow bandwidth modes (~ 650MHz). Six pairs of photons are selected to form a fully and simultaneously connected four-user quantum network. The observed quantum interference visibilities are well above the classical limits among all users. Each pair of users perform the BBM92 protocol for quantum key distribution. Our results pave the way for realizing large-scale quantum networks with integrated photonic architecture.
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