Article
Physics, Multidisciplinary
Sofus Laguna Kristensen, Eliot Bohr, Julian Robinson-Tait, Tanya Zelevinsky, Jan W. Thomsen, Jorg Helge Mueller
Summary: Superradiant lasers operate in the bad-cavity regime, where the phase coherence is stored in the spin state of an atomic medium rather than in the intracavity electric field. These lasers use collective effects to sustain lasing and could potentially reach considerably lower linewidths than a conventional laser. In this study, we investigate the properties of superradiant lasing in an ensemble of ultracold 88Sr atoms inside an optical cavity and achieve a lasing linewidth of 820 Hz for 1.1 ms, nearly an order of magnitude lower than the natural linewidth.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Comfort Sekga, Mhlambululi Mafu, Makhamisa Senekane
Summary: In this study, a high-dimensional measurement device-independent (MDI) quantum key distribution (QKD) protocol using biphotons to encode information is proposed. The protocol improves the tolerance to error rate by exploiting biphotons as qutrits. The independence of measurement devices and the use of finite key analysis approach are notable features. Results show a considerable secret key rate for a moderate transmission distance of 90 km using a minimum data size realizable with current technology. This protocol makes a significant step forward in realizing practical QKD implementations.
SCIENTIFIC REPORTS
(2023)
Article
Optics
Yuyao Guo, Xinhang Li, Minhui Jin, Liangjun Lu, Jingya Xie, Jianping Chen, Linjie Zhou
Summary: This article introduces a hybrid-integrated external cavity laser, which achieves a tunable range of 172 nm and a side-mode suppression ratio of over 40 dB using a broadband reflective semiconductor optical amplifier and a low-loss Si3N4 wavelength-selective reflector. The Si3N4 platform enables a low-loss external cavity, reducing the laser linewidth to below 4 kHz over the full tuning range.
Article
Optics
Yu-Sheng Wang, Kai-Bo Li, Chao-Feng Chang, Tan-Wen Lin, Jian-Qing Li, Shih-Si Hsiao, Jia-Mou Chen, Yi-Hua Lai, Ying-Cheng Chen, Yong-Fan Chen, Chih-Sung Chuu, Ite A. Yu
Summary: This report presents the generation of biphotons with the longest temporal width and the narrowest spectral linewidth to date. It also demonstrates a highly tunable-linewidth biphoton source and achieves a high-efficiency ultranarrow-linewidth biphoton source. These results are significant for quantum technology utilizing heralded single photons.
Article
Materials Science, Multidisciplinary
Kangkang Li, Yuan Zhao, Yishan Qin, Zhili Chen, Yin Cai, Yanpeng Zhang
Summary: Biphoton states play a crucial role in quantum technologies, especially in quantum information processing. This experimental study focuses on shaping the temporal correlation of biphotons in a hot Rb atomic ensemble through four-wave mixing, showing potential for enriching biphoton features with additional dressing fields.
ADVANCED PHOTONICS RESEARCH
(2021)
Article
Optics
Lang Li, Tao Wang, Xinhang Li, Peng Huang, Yuyao Guo, Liangjun Lu, Linjie Zhou, Guihua Zeng
Summary: Integrated quantum key distribution (QKD) systems based on photonic chips show promise for building global quantum communications networks. We designed and fabricated two on-chip tunable lasers for continuous-variable QKD (CVQKD) and demonstrated a high-performance system based on these sources. The on-chip lasers provide accurate detection of quantum signals, alignment of nonhomologous lasers, and suppression of excess noise, resulting in a secret key rate of 0.75 Mb/s at a 50 km fiber distance and a secure transmission distance of over 100 km. These results are a breakthrough toward fully integrated CV-QKD and lay the foundation for a reliable and efficient terrestrial quantum-secure metropolitan area network.
PHOTONICS RESEARCH
(2023)
Article
Optics
Shih-Si Hsiao, Wei-Kai Huang, Yi-Min Lin, Jia-Mou Chen, Chia-Yu Hsu, Ite A. Yu
Summary: In this study, the temporal profile of biphotons generated from a hot atomic vapor via four-wave mixing was systematically studied. An analytical expression of the biphoton's spectral profile in the Doppler-broadened medium was derived. The study found that the spectral profile is mainly determined by the effect of electromagnetically induced transparency (EIT) and the biphoton's temporal profile influenced by the Doppler broadening is an exponential-decay function.
Article
Optics
Xuan He, Weiwei Ke
Summary: This paper investigates the temporal characteristics of the light output from optical fibers with PRBS modulated laser injection and finds significant temporal fluctuations. Based on the exploration of clock rate and PRBS pattern, it is demonstrated that these fluctuations arise from the long dwell times in PRBS patterns. Finally, modified PRBS patterns are proposed to eliminate intense pulses.
Article
Optics
Chul Wook Lee, Oh Kee Kwon, Ki Soo Kim
Summary: We proposed a thermally-tuned distributed Bragg reflector (DBR) laser diode that has a high tuning efficiency over a wide wavelength tuning range. The laser diode is finely tuned by micro-heaters on the DBR and PC regions, and a thermal isolation structure is fabricated through a reverse mesa etching process to improve the tuning efficiency. The DBR laser diodes (DBR-LD) fabricated using this method have achieved a tuning range of approximately 40 nm, nearly four times larger than those without a thermal isolation structure.
Article
Polymer Science
Lin Wang, Arzugul Muslim, Dilhumar Turdi, Madina Salam, Zumratgul Tursun
Summary: In this study, the morphology and size of polyaniline (PANI) particles were controllably adjusted using a temperature-sensitive block copolymer template, resulting in uniform length distribution. The electrochemical performance of PANI showed good activity with a discharge-specific capacitance of up to 805.61 F center dot g(-1) at a current density of 1 A center dot g(-1).
POLYMERS FOR ADVANCED TECHNOLOGIES
(2021)
Article
Materials Science, Multidisciplinary
Preeti Sharma, Nishant Kumar Pathak, Bhaskar Kanseri
Summary: The study reveals a significant impact of the spatial coherence of the pump on polarization entanglement, and utilizing quantum states for free-space quantum secure communication can offer increased robustness.
RESULTS IN PHYSICS
(2021)
Article
Optics
Andrew Spencer, Bryan Barr, Angus Bell, Joseph Briggs, Andrew Minty, Borja Sorazu, Jennifer Wright, Kenneth Strain
Summary: Longer wavelength lasers are necessary for future gravitational wave detectors with cryogenic cooling. This study presents a frequency stabilisation system for a 1550 nm external cavity diode laser that reduces frequency noise and demonstrates high speed digital filter optimization.
Article
Engineering, Electrical & Electronic
Keqin Liu, Teng Zhang, Bingjie Dang, Lin Bao, Liying Xu, Caidie Cheng, Zhen Yang, Ru Huang, Yuchao Yang
Summary: Researchers have developed an optoelectronic synapse based on alpha-In2Se3 for creating a reservoir computing system capable of multimode and multiscale signal processing. By controlling the temporal dynamics of the synapse, adjustable nonlinear transformations and multisensory fusion are achieved. The relaxation timescale of the alpha-In2Se3 synapse is also tunable, allowing for the creation of a multiscale reservoir computing system.
NATURE ELECTRONICS
(2022)
Article
Optics
Tetsushi Takano, Hisashi Ogawa, Chiaki Ohae, Masayuki Katsuragawa
Summary: A high-power injection-locked titanium:sapphire laser with a low-loss cavity configuration was reported, achieving 10 W single-frequency oscillation with a good transverse mode and a slope efficiency of 5170.
Article
Optics
Junxiang Zhang, Quan Sheng, Lu Zhang, Chaodu Shi, Shuai Sun, Xiaolei Bai, Wei Shi, Jianquan Yao
Summary: The single-frequency operation of a thulium fiber laser at a short wavelength of 1720 nm was investigated, achieving powerful single-longitudinal-mode operation using an unpumped thulium-doped fiber as the saturable absorber. The fiber laser delivered 407 mW single-frequency output with a spectral linewidth of 4.4 kHz under 2.7-W launched pump power at 1570 nm, transitioning to multi-longitudinal-mode operation at higher pump powers, with optical bistability observed.
Article
Materials Science, Multidisciplinary
Zhuohui Zeng, Chenbo Zhang, Shengwang Du, Xian Chen
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2019)
Article
Physics, Multidisciplinary
Yefeng Mei, Yiru Zhou, Shanchao Zhang, Jianfeng Li, Kaiyu Liao, Hui Yan, Shi-Liang Zhu, Shengwang Du
PHYSICAL REVIEW LETTERS
(2020)
Article
Materials Science, Multidisciplinary
Zhuohui Zeng, Hoi-Chun Chiu, Luwei Zhao, Teng Zhao, Chenbo Zhang, Mostafa Karami, Hongyu Yu, Shengwang Du, Xian Chen
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2020)
Article
Optics
Ming Kang, Kai Ming Lau, Tsz Kit Yung, Shengwang Du, Wing Yim Tam, Jensen Li
Summary: The complex and flexible light-matter interaction between dielectric metasurfaces and incident light can be used to perform quantum bit operations and extend to two-qubit operations. Efficient utilization of metasurfaces as a compact platform can simplify optical qubit operations.
Article
Physics, Applied
Ying Zuo, Yujun Zhao, You-Chiuan Chen, Shengwang Du, Junwei Liu
Summary: This study demonstrates a scalable optical artificial neural network with programmable linear operations and tunable nonlinear activation functions, confirming its feasibility through error measurements and analysis, and successfully recognizing handwritten digits and fashions.
PHYSICAL REVIEW APPLIED
(2021)
Article
Optics
Jianming Wen, Irina Novikova, Chen Qian, Chuanwei Zhang, Shengwang Du
Summary: By proposing a new scheme to remotely generate hybrid entanglement between discrete polarization and continuous quadrature optical qubits heralded by two-photon Bell-state measurement, the study explores potential applications of hybrid entanglement in quantum information processing and communications through examples of entanglement swapping and quantum teleportation.
Article
Physics, Multidisciplinary
Xi-Wang Luo, Chuanwei Zhang, Shengwang Du
Summary: This research establishes a quantum pseudo-anti-PT (pseudo-APT) symmetry which, when spontaneously broken, leads to the generation of an exceptional point that can be utilized for ultraprecision quantum sensing applications.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Multidisciplinary
Ka Hung Chan, Shengwang Du, Xian Chen
Summary: This study presents a theoretical exploration of surface step characterization using reflected incoherent-light differential interference microscopy, with consideration of the optical diffraction effect. By integrating localization analysis, a quantitative differential interference optical system is developed, which demonstrates high axial resolution in measuring surface height variation. The experiment successfully characterizes nanometer-size steps with subnanometer accuracy, indicating the potential of optical differential interference microscopy for real-time surface structure characterization in micro/nano-electromechanical systems.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Rong Chen, Xiao Tang, Yuxuan Zhao, Zeyu Shen, Meng Zhang, Yusheng Shen, Tiantian Li, Casper Ho Yin Chung, Lijuan Zhang, Ji Wang, Binbin Cui, Peng Fei, Yusong Guo, Shengwang Du, Shuhuai Yao
Summary: A deep-learning-based single-frame super-resolution microscopy method is proposed, which allows for high spatiotemporal resolution imaging of cellular dynamics. It overcomes the limitations of multi-frame super-resolution microscopy in terms of long acquisition times and phototoxicity.
NATURE COMMUNICATIONS
(2023)
Article
Biology
Zeyu Shen, Bowen Jia, Yang Xu, Jonas Wessen, Tanmoy Pal, Hue Sun Chan, Shengwang Du, Mingjie Zhang, Rohit Pappu
Summary: Formation of membraneless organelles or biological condensates via phase separation expands the cellular organelle repertoire. In this study, an adaptive single-molecule imaging method was developed to track individual molecules in various biological condensates. The method enables measurements of concentrations, motion behavior, and molecular exchanges between condensed and dilute phases. The findings offer insights into the molecular mechanisms underlying the assembly and dynamics of biological condensates.
Article
Quantum Science & Technology
Eun Oh, Xuanying Lai, Jianming Wen, Shengwang Du
Summary: The promise of universal quantum computing requires scalable control interactions between single or multiple qubits. Current leading candidate platforms for quantum computing, superconducting circuits, trapped ions, and neutral atom arrays, suffer from strong interaction with environmental and control noises resulting in qubit decoherence. Photons, on the other hand, have advantages of being well decoupled from the environment and having high speed and timing capabilities. This article proposes a universal distributed quantum computing scheme based on photons and atomic-ensemble-based quantum memories, showcasing the potential of a photon-atom network hybrid approach.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Optics
Yue Jiang, Yefeng Mei, Shengwang Du
Summary: We propose a macroscopic phenomenological formula for quantum Langevin equations describing two coupled phase-conjugated electromagnetic fields with linear loss (gain) and complex nonlinear coupling coefficient. This formula, obtained from the coupling matrix, preserves the field commutation relations and correlations without requiring knowledge of microscopic light-matter interaction and atomic structures. We validate the formula by numerically confirming its consistency with the microscopic Heisenberg-Langevin theory in the context of spontaneous four-wave mixing in a double-four-level atomic system. We also find that a complex-valued nonlinear coupling coefficient can induce noise even in the absence of linear gain or loss. Finally, we apply the quantum Langevin equations to study the effects of linear gain and loss, complex phase mismatching, and complex nonlinear coupling coefficient on entangled photon pair generation, particularly their temporal quantum correlations.
Article
Optics
Xi-Wang Luo, Chuanwei Zhang, Irina Novikova, Chen Qian, Shengwang Du
Summary: This study proposes a wavelength conversion device for single-photon polarization qubits using continuous-variable quantum teleportation. It efficiently converts qubits between near-infrared and telecom wavelength, potentially paving the way for long-distance quantum networks.
Article
Optics
Ying Zuo, Chenfeng Cao, Ningping Cao, Xuanying Lai, Bei Zeng, Shengwang Du
Summary: Quantum state tomography (QST) is crucial for experimental quantum information processing, and optical neural networks (ONN) show promising potential in photonic polarization qubit QST.
ADVANCED PHOTONICS
(2022)
Article
Optics
Bojeong Seo, Peng Chen, Ziting Chen, Weijun Yuan, Mingchen Huang, Shengwang Du, Gyu-Boong Jo
