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Quantum microwave photonic mixer featuring high linearity and dual outputs

Physical Review Applied 2025年第1期23卷 014078-014078页

作者： Xinghua Li Yifan Guo Xiao Xiang Runai Quan Junjie Xing Ruifang Dong Tao Liu Mingtao Cao Ming Li Key Laboratory of Time Reference and Applications National Time Service Center Chinese Academy of Sciences Xi’an 710600 Shaanxi China School of Astronomy and Space Science University of Chinese Academy of Sciences 100049 Beijing China Hefei National Laboratory Hefei 230088 Anhui China State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences 100083 Beijing China School of Electronic Electrical and Communication Engineering University of Chinese Academy of Sciences 100049 Beijing China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences 100190 Beijing China

Microwave frequency mixing is a fundamental functionality in microwave photonics, playing a crucial role in modern radar and wireless communication systems. Classical microwave photonic mixers require both the radio frequency (rf) signal and the local oscillator to be loaded onto the same optical light source, thereby impeding their capability in the context of distributed microwave systems. Using time-energy–entangled biphotons as the optical carrier, the quantum microwave photonic (QMWP) mixer offers a promising solution for attaining nonlocal mixing and surmounting such limitations. In this paper, we explore two types of QMWP mixer based on the configuration of the intensity modulators: cascade type and parallel type. Both QMWP mixers feature the properties of high linearity and dual outputs, with their spurious-free dynamic ranges being identical to that of the equivalent classical microwave photonic mixer. Specifically, the parallel-type QMWP mixer can nonlocally mix two physically separated rf signals, demonstrating its superiority in distributed microwave and millimeter-wave radar systems. Further, by application of multiphoton frequency-entangled sources as optical carriers, the nonlocal microwave frequency conversion capability endowed by the QMWP mixer can be extended to enhance the performance of multiple-path microwave mixing, which is essential for radar net systems.

关键词： Microwave photonics

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Stationary states of a trapped SU(3) spin-orbit-coupled Bose gas with soft-core interaction

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Physical Review A 2025年第4期111卷 043302-043302页

作者： Jia Liu Jing Feng Si-Lin Chen Lin Wen Wei Han Xiao-Fei Zhang Xue-Ying Yang School of Physics and Information Science Shaanxi University of Science and Technology Xi'an 710021 China Shaanxi Key Laboratory for Theoretical Physics Frontiers Institute of Modern Physics Northwest University Xi'an 710127 China College of Physics and Electronic Engineering Chongqing Normal University Chongqing 400047 China State Key Laboratory of Quantum Optics Technologies and Devices Institute of Opto-Electronics Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan 030006 China Key Laboratory of Time Reference and Applications National Time Service Center Chinese Academy of Sciences Xi'an 710600 China

We consider a SU(3) spin-orbit-coupled Bose gas with nonlocal soft-core interactions confined in a harmonic trapping potential. The presence of SU(3) spin-orbit coupling induces three minima of the single-particle spectrum. In the absence of spin-exchange interaction, our results show that regardless of the sign of the soft-core interaction, the ground state occupies one single minimum in the momentum space and corresponds to a threefold-degenerate magnetized phase. For the ferromagnetic condensate, the ground state shows an amplitude-modulated plane-wave state, where its modulated amplitude and frequency are related to the strength of the soft-core interaction and SU(3) spin-orbit coupling, respectively. In particular, due to the subtle balance of the soft-core interaction and SU(3) spin-orbit coupling, a stable higher-order spin vortex lattice can be formed in the lattice phase of an antiferromagnetic condensate, where the density distributions of each component and the total system show spatial configurations with threefold and sixfold symmetries, respectively. We also give an experimental protocol to observe such states within current experimental capacity.

关键词： Spin orbit coupling

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Towards a function-scalable quantum network with multiplexed energy-time entanglement

arXiv

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arXiv 2025年

作者： Xiang, Xiao Liu, Jingyuan Shi, Bingke Hong, Huibo Sun, Xizi Liu, Yuting Quan, Runai Liu, Tao Zhang, Shougang Zhang, Wei Dong, Ruifang Key Laboratory of Time Reference and Applications National Time Service Center Chinese Academy of Sciences Xi’an710600 China State Key Laboratory of Low-Dimensional Quantum Physics Frontier Science Center for Quantum Information Electronic Engineering Department Tsinghua University Beijing100084 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Beijing Academy of Quantum Information Sciences Beijing100193 China Hefei National Laboratory Hefei230088 China

Quantum networks, which hinge on the principles of quantum mechanics, are revolutionizing the domain of information technology. The vision for quantum networks involves the efficient distribution and utilization of quantum resources across a network to support a variety of quantum applications. However, current quantum protocols often develop independently, leading to incompatibilities that limit the functional scalability of the network. In this paper, we showcase a compatible and complementary implementation of two distinct quantum applications, quantum time synchronization and quantum cryptography, by multiplexing the same energy-time entangled biphotons and quantum channel. A proof-of-principle experiment between two independent nodes across a 120 km fiber-optic link is demonstrated, which achieve sub-picosecond synchronization stability based on the quantum two-way time transfer protocol. Simultaneously, this synchronization provides the required timing for implementing dispersive-optic quantum key distribution with an average finite-size secure key rate of 73.8 bits per second, which can be employed to safeguard the security of the transferred timing data. Furthermore, thanks to the compatibility, potential asymmetric delay attacks in the link, which are detrimental to the accomplishment of secure key distribution, can be effectively mitigated by the parallel quantum time synchronization procedure. Our demonstration marks a substantial leap towards unlocking the full potential of energy-time entanglement and paves the way for a resource-efficient, function-scalable, and highly compatible quantum network. Copyright © 2025, The Authors. All rights reserved.

关键词： Quantum channel

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time transfer over a 2061 km telecommunication fiber-optic network with single-fiber and two-wavelength approach

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Chinese Optics Letters 2025年第4期23卷 041404-041404页

作者： Guo, Xinxing Liu, Bo Yu, Shaoshao Jing, Qian Chen, Jiang Wu, Lin Liu, Tao Dong, Ruifang Zhang, Shougang National Time Service Center Chinese Academy of Sciences Key Laboratory of Time Reference and Applications Xi’an710600 China School of Science Xi’An Shiyou University Xi’an710065 China University of Chinese Academy of Sciences School of Astronomy and Space Science Beijing100049 China

In this paper, we demonstrate the single-fiber and two-wavelength time transfer (SFTWTT) over a 2061 km field fiber loop-back link network with a synchronous wavelength-division and time-division multiplexing access (WD-TDMA). This system utilizes wavelength-division multiplexing to avoid the impact of backscatter. In order to achieve high-precision time transfer, time-division multiplexing access is employed. This approach facilitates multiple bidirectional comparisons between local and remote devices. A digital phase-locked loop (PLL), which matches the bandwidth of the transfer system, and precision temperature control technology have been proposed to enhance the high stability of the fiber-optic time and frequency transfer system. The first on-site high-precision fiber-optic time transfer system exceeding 2000 km has been validated. Experimental results show that the stabilities of 5.6 ps@1 s and 3.1 ps@40,000 s can be achieved. The precision of time transfer over a 2061 km fiber-optic network, employing a single-fiber and two-wavelength approach, has been significantly enhanced. This study presents an average time difference of 52 ps across the distance, with a system uncertainty budgeted at 41.8 ps. This achievement signifies a substantial advancement in the realms of stability and reach for optical fiber time transfer, facilitating the development of a high-precision ground-based time service system. © 2025 Chinese Optics Letters.

关键词： Budget control

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Clock laser noise constraining synchronous comparison of spin-squeezed optical clocks

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Physics Letters, Section A: General, Atomic and Solid State Physics 2025年 552卷

作者： Yu, Deshui Zhang, Shougang Chen, Jingbiao National Time Service Center Chinese Academy of Sciences Xi'an710600 China Key Laboratory of Time Reference and Applications Chinese Academy of Sciences Xi'an710600 China University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Photonics and Communications Institute of Quantum Electronics School of Electronics Peking University Beijing100871 China Hefei National Laboratory Hefei230088 China

Spin squeezing has been recognized as a powerful tool to overcome the quantum projection noise limit that is imposed on optical clocks with uncorrelated atoms. Yet, the full potential of spin squeezing remains underutilized in precision measurement, due to the limited Ramsey dark period, which is much shorter than 1 s-level atom-laser and 10 s-level atom-atom coherence times. Here, we numerically study the impact of the clock laser noise on the synchronous comparison of spin-squeezed optical clocks. We restrict ourselves to one-axis twisting and measurement-induced spin squeezing protocols that have recently been demonstrated on optical lattice clocks. The simulation results illustrate that for typical lattice clocks with 103 atoms, the metrological enhancement induced by spin squeezing is only attainable for a dark period of less than 0.1 s using the state-of-the-art clock laser. Therefore, further improvement of the clock laser is necessary to bring spin squeezing into the full play. © 2025 Elsevier B.V.

关键词： Clocks

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An Improved Design of Atomic-Beam Fluorescence Collector 37

An Improved Design of Atomic-Beam Fluorescence Collector

引用

37th European Frequency and time Forum, EFTF 2024

作者： Hu, Xuwen Sun, Fuyu Li, Chao Liu, Jie Li, Xiaofeng Zhang, Shougang National Time Service Center Chinese Academy of Sciences Xi'an China Chinese Academy of Sciences Key Laboratory of Time Reference and Applications Xi'an China

ISBN: (纸本)9798350354270

Efficient fluorescence detection is crucial in the field of precision spectral analysis. This paper presents an improved design of an atomic-beam fluorescence collector that utilizes the convergence characteristics of ellipsoidal surfaces and the reflection characteristics of spherical surfaces. It calculates the parameter relationship for achieving full-angle fluorescence collection. The study fine-tunes the structural parameters and simulates the fluorescence collection efficiency and losses under different conditions when emitting from a non-ideal point light source. The improved fluorescence collector captures photons with nearly 4n solid angle coverage, allowing photons to be reflected at most twice before reaching the photo detector, thereby increasing collection efficiency. This improved collector can be used in various fields for detecting weak fluorescence signals. © 2024 IEEE.

关键词： Fluorescence microscopy

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A Compact Optically Pumped Cesium Beam Clock with a Differential Detection Scheme 37

A Compact Optically Pumped Cesium Beam Clock with a Differen...

引用

37th European Frequency and time Forum, EFTF 2024

作者： Li, Chao Sun, Fuyu Hu, Xuwen Liu, Jie Li, Xiaofeng Zhang, Shougang National Time Service Center Chinese Academy of Sciences Xi'an China Chinese Academy of Sciences Key Laboratory of Time Reference and Applications Xi'an China

ISBN: (纸本)9798350354270

Compact optically pumped cesium beam clocks have become a focus in cesium clock research due to their high atomic utilization and excellent short-term frequency stability. However, stray light noise, one of the main noise sources, limits the stability improvement. In this paper, we present a compact optically pumped cesium clock that uses differential detection to reduce the impact of stray light on clock performance. It incorporates an additional fluorescence collector to capture stray light during detection and subtract it from the clock transition signal, effectively reducing stray light level. Consequently, this scheme significantly enhances the signal-to-noise ratio, improving the short-term frequency stability of the compact optically pumped cesium clock. © 2024 IEEE.

关键词： Frequency stability

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Combined Separated Oscillatory Fields Technique 37

Combined Separated Oscillatory Fields Technique

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37th European Frequency and time Forum, EFTF 2024

作者： Sun, Fuyu Li, Chao Hu, Xuwen Zhang, Shougang National Time Service Center Chinese Academy of Sciences Xi'an China Chinese Academy of Sciences Key Laboratory of Time Reference and Applications Xi'an China

ISBN: (纸本)9798350354270

Ramsey's method of separated oscillatory fields (SOFs) has been originally used in beam magnetic resonance apparatuses, which leads to the establishment of atomic definition of time interval and frequency. Since then, various versions of the SOFs technique have been widely used for precise measurement of different physical quantities. Here, we present an alternative method to generate atomic beam magnetic resonance signals by combining two Ramsey cavities with phase differences of 0 and 1t. It is found that the strength of the resonance signals generated using this combined SOFs technique is approximately twice that of the resonance signals produced by the conventional SOFs techniques. In addition to generating stronger resonance, the combined Ramsey method eliminates the Rabi background superimposed on the Ramsey interference pattern without increasing the Ramsey signal linewidth. Thus, this technique serves a promising tool for high-precision measurements. © 2024 IEEE.

关键词： Velocity measurement

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Observation of time crystal in a spin maser system

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Communications Physics 2025年第1期8卷 1-6页

作者： Wang, Weiyu Feng, Mingjun Ma, Qianjin Cai, Zi Li, Erwei Liu, Guobin National Time Service Center Chinese Academy of Sciences Xi’an China Key Laboratory of Time Reference and Applications Chinese Academy of Sciences Xi’an China University of Chinese Academy of Sciences Beijing China Wilczek Quantum Center and Key Laboratory of Artificial Structures and Quantum Control School of Physics and Astronomy Shanghai Jiao Tong University Shanghai China Shanghai Research Center for Quantum Sciences Shanghai China

Pair interaction potentials between atoms in a crystal are in general non-monotonic in distance, with a local minimum whose position gives the lattice constant of the crystal. A temporal analogue of this idea of crystal formation is still pending despite intensive studies on the time crystal phase. In a hybrid spin maser system with a time delay feedback, we report the observation of a time crystal induced by a retarded interaction with a characteristic time scale. This nonequilibrium phase features a self-sustained oscillation with an emergent frequency other than the intrinsic Larmor precession frequency of the spin maser system. It is shown that the amplitude of the oscillation is robust against perturbation, while its time phase randomly distributes from 0 to 2π for different realizations, a signature of spontaneous time translation symmetry breaking. This time crystal phase emerges only when the feedback strength exceeds a critical value, at which the system experiences a first order phase transition. Such a retarded interaction induced time crystal is closer to the idea of crystal, compared to other time crystal realizations. © The Author(s) 2025.

关键词： Lattice constants

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Optical storage of circular airy beam in atomic vapor

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Chinese Physics B 2024年第8期33卷 263-269页

作者：常虹杨欣马燕杨鑫琪曹明涛张晓斐董瑞芳张首刚 Key Laboratory of Time Reference and Applications National Time Service CenterChinese Academy of SciencesXi'an 710600China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic DevicesSchool of PhysicsXi'an Jiaotong UniversityXi'an 710049China Department of Physics Shaanxi University of Science and TechnologyXi'an 710021China Hefei National Laboratory Hefei 230088China

The realization of quantum storage of spatial light field is of great significance to the construction of high-dimensional quantum *** this paper,we experimentally realize the storage and retrieval of circular Airy beams(CABs)by using theΛ-type three-level energy system based on the electromagnetically induced transparency in a hot rubidium atomic vapor *** weak probe beam field is modulated with phase distribution of CABs by a spatial light *** store the probe circular Airy beam(CAB)into the rubidium atomic vapor cell and retrieve it after the demanded *** quantitatively analyze the storage results and give corresponding theoretical ***,we investigate the autofocusing and self-healing effect of the retrieved CAB,which indicates that the properties and beam shape of CAB maintain well after *** work will have potential applications in the storage of high-dimensional quantum information,and is also useful for improving the channel capacities of quantum internet.

关键词： circular Airy beam optical storage autofocusing effect self-healing effect

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