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Quantum Optics|123 Article(s)
Experimental demonstration of complete quantum e-commerce based on an efficient quantum digital payment
Shuaishuai Liu, Yu Zhang, Shaobo Ren, Si Qiu, Zhenguo Lu, Xuyang Wang, and Yongmin Li
With the rapid spread of Internet technology, e-commerce is gradually becoming an integral part of the modern business models. The e-commerce transactions should obey integrity, authentication, nonrepudiation, traceability, and impartiality. Here, we propose and demonstrate a complete continuous-variable quantum e-commerce scheme, which involves subscription, payment, transport, and reception protocols among five parties. To this end, a simple, efficient quantum digital payment scheme is proposed. Furthermore, we streamline the entire e-commerce process by eliminating the private amplification step in the pre-distribution of keys. We achieve a contract signing rate of 1.51×103 times per second for a 33 kilobits contract, and a payment rate of 2.70×103 times per second over 80 km of single-mode fiber. Our results can support 411 times complete transactions per second, including three contract signings and two separate monetary payments. The proposed scheme takes into account the compatibility with existing e-commerce platforms to ensure a smooth transition and provides a practical solution for quantum e-commerce at metropolitan distances. With the rapid spread of Internet technology, e-commerce is gradually becoming an integral part of the modern business models. The e-commerce transactions should obey integrity, authentication, nonrepudiation, traceability, and impartiality. Here, we propose and demonstrate a complete continuous-variable quantum e-commerce scheme, which involves subscription, payment, transport, and reception protocols among five parties. To this end, a simple, efficient quantum digital payment scheme is proposed. Furthermore, we streamline the entire e-commerce process by eliminating the private amplification step in the pre-distribution of keys. We achieve a contract signing rate of 1.51×103 times per second for a 33 kilobits contract, and a payment rate of 2.70×103 times per second over 80 km of single-mode fiber. Our results can support 411 times complete transactions per second, including three contract signings and two separate monetary payments. The proposed scheme takes into account the compatibility with existing e-commerce platforms to ensure a smooth transition and provides a practical solution for quantum e-commerce at metropolitan distances.
Photonics Research
- Publication Date: Feb. 18, 2025
- Vol. 13, Issue 3, 572 (2025)
Composite phase-based metasurfaces for the generation of spin-decoupling orbital angular momentum single-photon sources
Hongxin Huang, Xiaodi Liu, Yongle Zhou, He Li, and Juntao Li
Solid-state quantum emitters, such as semiconductor quantum dots (QDs), have numerous significant applications in quantum information science. While there has been some success in controlling structured light from kinds of single-photon sources, the simultaneous on-demand, high-quality, and integrated generation of single-photon sources with various degrees of freedom remains a challenge. Here, we utilize composite phase-based metasurfaces, comprising transmission phase and geometric phase elements, to modulate the semiconductor QD emission through a simplified fabrication process. This approach enables to decouple the emission into left and right circularly polarized (LCP/RCP) beams in arbitrary directions (e.g., with zenith angles of 10° and 30°), producing collimated beams with divergence angles less than 6.0° and carrying orbital angular momentum (OAM) modes with different topological charges. Furthermore, we examine the polarization relationship between the output beams and QD emission to validate the performance of our designed devices. Additionally, we achieve eight channels of single-photon emissions, each with well-defined states of spin angular momentum (SAM), OAM, and specific emission directions. Our work not only demonstrates an effective integrated quantum device for the on-demand manipulation of precise direction, collimation, SAM, and various OAM modes, but also significantly advances research efforts in the quantum field related to the generation of multi-OAM single photons. Solid-state quantum emitters, such as semiconductor quantum dots (QDs), have numerous significant applications in quantum information science. While there has been some success in controlling structured light from kinds of single-photon sources, the simultaneous on-demand, high-quality, and integrated generation of single-photon sources with various degrees of freedom remains a challenge. Here, we utilize composite phase-based metasurfaces, comprising transmission phase and geometric phase elements, to modulate the semiconductor QD emission through a simplified fabrication process. This approach enables to decouple the emission into left and right circularly polarized (LCP/RCP) beams in arbitrary directions (e.g., with zenith angles of 10° and 30°), producing collimated beams with divergence angles less than 6.0° and carrying orbital angular momentum (OAM) modes with different topological charges. Furthermore, we examine the polarization relationship between the output beams and QD emission to validate the performance of our designed devices. Additionally, we achieve eight channels of single-photon emissions, each with well-defined states of spin angular momentum (SAM), OAM, and specific emission directions. Our work not only demonstrates an effective integrated quantum device for the on-demand manipulation of precise direction, collimation, SAM, and various OAM modes, but also significantly advances research efforts in the quantum field related to the generation of multi-OAM single photons.
Photonics Research
- Publication Date: Jan. 30, 2025
- Vol. 13, Issue 2, 442 (2025)
Realization of edge states along a synthetic orbital angular momentum dimension|Spotlight on Optics
Yu-Wei Liao, Mu Yang, Hao-Qing Zhang, Zhi-He Hao, Jun Hu, Tian-Xiang Zhu, Zong-Quan Zhou, Xi-Wang Luo, Jin-Shi Xu, Chuan-Feng Li, and Guang-Can Guo
Synthetic dimensions have emerged as promising methodologies for studying topological physics, offering great advantages in controllability and flexibility. Photonic orbital angular momentum (OAM), characterized by discrete yet unbounded properties, serves as a potent carrier for constructing synthetic dimensions. Despite the widespread utilization of synthetic OAM dimensions in the investigation of topological physics, the demonstration of an edge along such dimensions has remained challenging, significantly constraining the exploration of important topological edge effects. In this study, we establish an edge within a Floquet Su–Schrieffer–Heeger OAM lattice, creating approximate semi-infinite lattices by introducing a pinhole in the optical elements within a cavity. Leveraging the spectral detection capabilities of the cavity, we directly measure the phase transitions of zero (±π) energy edge states, elucidating the principle of bulk-edge correspondence. Furthermore, we dynamically observe the migration of edge modes from the gap to the bulk by varying the edge phase, and we reveal that interference near the surface results in the discretization of the spectrum. We offer, to our knowledge, a novel perspective for investigating edge effects and provide an important photonic toolbox in topological photonics. Synthetic dimensions have emerged as promising methodologies for studying topological physics, offering great advantages in controllability and flexibility. Photonic orbital angular momentum (OAM), characterized by discrete yet unbounded properties, serves as a potent carrier for constructing synthetic dimensions. Despite the widespread utilization of synthetic OAM dimensions in the investigation of topological physics, the demonstration of an edge along such dimensions has remained challenging, significantly constraining the exploration of important topological edge effects. In this study, we establish an edge within a Floquet Su–Schrieffer–Heeger OAM lattice, creating approximate semi-infinite lattices by introducing a pinhole in the optical elements within a cavity. Leveraging the spectral detection capabilities of the cavity, we directly measure the phase transitions of zero (±π) energy edge states, elucidating the principle of bulk-edge correspondence. Furthermore, we dynamically observe the migration of edge modes from the gap to the bulk by varying the edge phase, and we reveal that interference near the surface results in the discretization of the spectrum. We offer, to our knowledge, a novel perspective for investigating edge effects and provide an important photonic toolbox in topological photonics.
Photonics Research
- Publication Date: Dec. 20, 2024
- Vol. 13, Issue 1, 87 (2025)
On-chip topological transport of integrated optical frequency combs|Editors' Pick
Zhen Jiang, Hongwei Wang, Peng Xie, Yuechen Yang, Yang Shen, Bo Ji, Yanghe Chen, Yong Zhang, Lu Sun, Zheng Wang, Chun Jiang, Yikai Su, and Guangqiang He
Optical frequency combs in integrated photonics have widespread applications in high-dimensional optical computing, high-capacity communications, high-speed interconnects, and other paradigm-shifting technologies. However, quantum frequency combs with high-dimensional quantum states are vulnerable to decoherence, particularly in the presence of perturbations such as sharp bends. Here we experimentally demonstrate the robust on-chip topological transport of quantum frequency combs in valley photonic crystal waveguides. By measuring the time correlations and joint spectral intensity of the quantum frequency combs, we show that both quantum correlations and frequency entanglement remain robust against sharp bends, owing to the topological nature of the quantum valley Hall effect. We also demonstrate that dissipative Kerr soliton combs with a bandwidth of 20 THz maintain their spectral envelope and low-noise properties even in the presence of structure perturbations. These topologically protected optical frequency combs offer robust, complex, highly controllable, and scalable light sources, promising significant advances in high-dimensional photonic information processing. Optical frequency combs in integrated photonics have widespread applications in high-dimensional optical computing, high-capacity communications, high-speed interconnects, and other paradigm-shifting technologies. However, quantum frequency combs with high-dimensional quantum states are vulnerable to decoherence, particularly in the presence of perturbations such as sharp bends. Here we experimentally demonstrate the robust on-chip topological transport of quantum frequency combs in valley photonic crystal waveguides. By measuring the time correlations and joint spectral intensity of the quantum frequency combs, we show that both quantum correlations and frequency entanglement remain robust against sharp bends, owing to the topological nature of the quantum valley Hall effect. We also demonstrate that dissipative Kerr soliton combs with a bandwidth of 20 THz maintain their spectral envelope and low-noise properties even in the presence of structure perturbations. These topologically protected optical frequency combs offer robust, complex, highly controllable, and scalable light sources, promising significant advances in high-dimensional photonic information processing.
Photonics Research
- Publication Date: Dec. 24, 2024
- Vol. 13, Issue 1, 163 (2025)
Programmable silicon-photonic quantum simulator based on a linear combination of unitaries|Editors' Pick
Yue Yu, Yulin Chi, Chonghao Zhai, Jieshan Huang, Qihuang Gong, and Jianwei Wang
Simulating the dynamic evolution of physical and molecular systems in a quantum computer is of fundamental interest in many applications. The implementation of dynamics simulation requires efficient quantum algorithms. The Lie-Trotter-Suzuki approximation algorithm, also known as the Trotterization, is basic in Hamiltonian dynamics simulation. A multi-product algorithm that is a linear combination of multiple Trotterizations has been proposed to improve the approximation accuracy. However, implementing such multi-product Trotterization in quantum computers remains challenging due to the requirements of highly controllable and precise quantum entangling operations with high success probability. Here, we report a programmable integrated-photonic quantum simulator based on a linear combination of unitaries, which can be tailored for implementing the linearly combined multiple Trotterizations, and on the simulator we benchmark quantum simulation of Hamiltonian dynamics. We modify the multi-product algorithm by integrating it with oblivious amplitude amplification to simultaneously reach high simulation precision and high success probability. The quantum simulator is devised and fabricated on a large-scale silicon-photonic quantum chip, which allows the initialization, manipulation, and measurement of arbitrary four-qubit states and linearly combined unitary gates. As an example, the quantum simulator is reprogrammed to emulate the dynamics of an electron spin and nuclear spin coupled system. This work promises the practical dynamics simulations of real-world physical and molecular systems in future large-scale quantum computers. Simulating the dynamic evolution of physical and molecular systems in a quantum computer is of fundamental interest in many applications. The implementation of dynamics simulation requires efficient quantum algorithms. The Lie-Trotter-Suzuki approximation algorithm, also known as the Trotterization, is basic in Hamiltonian dynamics simulation. A multi-product algorithm that is a linear combination of multiple Trotterizations has been proposed to improve the approximation accuracy. However, implementing such multi-product Trotterization in quantum computers remains challenging due to the requirements of highly controllable and precise quantum entangling operations with high success probability. Here, we report a programmable integrated-photonic quantum simulator based on a linear combination of unitaries, which can be tailored for implementing the linearly combined multiple Trotterizations, and on the simulator we benchmark quantum simulation of Hamiltonian dynamics. We modify the multi-product algorithm by integrating it with oblivious amplitude amplification to simultaneously reach high simulation precision and high success probability. The quantum simulator is devised and fabricated on a large-scale silicon-photonic quantum chip, which allows the initialization, manipulation, and measurement of arbitrary four-qubit states and linearly combined unitary gates. As an example, the quantum simulator is reprogrammed to emulate the dynamics of an electron spin and nuclear spin coupled system. This work promises the practical dynamics simulations of real-world physical and molecular systems in future large-scale quantum computers.
Photonics Research
- Publication Date: Aug. 01, 2024
- Vol. 12, Issue 8, 1760 (2024)
All-optical nanoscale thermometry with silicon carbide color centers|On the Cover
Chengying Liu, Haibo Hu, Zhengtong Liu, Shumin Xiao, Junfeng Wang, Yu Zhou, and Qinghai Song
All-optical thermometry plays a crucial role in precision temperature measurement across diverse fields. Quantum defects in solids are one of the most promising sensors due to their excellent sensitivity, stability, and biocompatibility. Yet, it faces limitations, such as the microwave heating effect and the complexity of spectral analysis. Addressing these challenges, we introduce a novel approach to nanoscale optical thermometry using quantum defects in silicon carbide (SiC), a material compatible with complementary metal-oxide-semiconductor (CMOS) processes. This method leverages the intensity ratio between anti-Stokes and Stokes emissions from SiC color centers, overcoming the drawbacks of traditional techniques such as optically detected magnetic resonance (ODMR) and zero-phonon line (ZPL) analysis. Our technique provides a real-time, highly sensitive (1.06%K-1), and diffraction-limited temperature sensing protocol, which potentially helps enhance thermal management in the future miniaturization of electronic components. All-optical thermometry plays a crucial role in precision temperature measurement across diverse fields. Quantum defects in solids are one of the most promising sensors due to their excellent sensitivity, stability, and biocompatibility. Yet, it faces limitations, such as the microwave heating effect and the complexity of spectral analysis. Addressing these challenges, we introduce a novel approach to nanoscale optical thermometry using quantum defects in silicon carbide (SiC), a material compatible with complementary metal-oxide-semiconductor (CMOS) processes. This method leverages the intensity ratio between anti-Stokes and Stokes emissions from SiC color centers, overcoming the drawbacks of traditional techniques such as optically detected magnetic resonance (ODMR) and zero-phonon line (ZPL) analysis. Our technique provides a real-time, highly sensitive (1.06%K-1), and diffraction-limited temperature sensing protocol, which potentially helps enhance thermal management in the future miniaturization of electronic components.
Photonics Research
- Publication Date: Aug. 01, 2024
- Vol. 12, Issue 8, 1696 (2024)
Gbps key rate passive-state-preparation continuous-variable quantum key distribution within an access-network area
Feiyu Ji, Peng Huang, Tao Wang, Xueqin Jiang, and Guihua Zeng
The conventional Gaussian-modulated coherent-state quantum key distribution (QKD) protocol requires the sender to perform active modulations based on a true random number generator. Compared with it, the passive-state-preparation (PSP) continuous-variable quantum key distribution (CVQKD) equivalently performs modulations passively by exploring the intrinsic field fluctuations of a thermal source, which offers the prospect of chip integration QKD with low cost. In this paper, we propose and experimentally demonstrate a high-rate PSP-CVQKD scheme within an access-network area using high-bandwidth detectors in a continuous wave encoding and decoding way. By proposing effective methods for suppressing the noises during the PSP process and polarization multiplexing to decrease the photon leakage noises, we realize the high-intensity local oscillator transmission, thereby achieving coherent detection with high efficiency, low noise, and high bandwidth. The secure key rates over transmission distance of 5.005 km with and without consideration of the finite-size effect are 273.25 Mbps and 1.09 Gbps. The use of the PSP method boosts the asymptotic secret key rate of CVQKD to Gbps level for the first time, to our knowledge, within the range of the access network, which provides an effective and secure key distribution strategy for high-speed quantum cryptography access communication. The conventional Gaussian-modulated coherent-state quantum key distribution (QKD) protocol requires the sender to perform active modulations based on a true random number generator. Compared with it, the passive-state-preparation (PSP) continuous-variable quantum key distribution (CVQKD) equivalently performs modulations passively by exploring the intrinsic field fluctuations of a thermal source, which offers the prospect of chip integration QKD with low cost. In this paper, we propose and experimentally demonstrate a high-rate PSP-CVQKD scheme within an access-network area using high-bandwidth detectors in a continuous wave encoding and decoding way. By proposing effective methods for suppressing the noises during the PSP process and polarization multiplexing to decrease the photon leakage noises, we realize the high-intensity local oscillator transmission, thereby achieving coherent detection with high efficiency, low noise, and high bandwidth. The secure key rates over transmission distance of 5.005 km with and without consideration of the finite-size effect are 273.25 Mbps and 1.09 Gbps. The use of the PSP method boosts the asymptotic secret key rate of CVQKD to Gbps level for the first time, to our knowledge, within the range of the access network, which provides an effective and secure key distribution strategy for high-speed quantum cryptography access communication.
Photonics Research
- Publication Date: Jul. 01, 2024
- Vol. 12, Issue 7, 1485 (2024)
On-chip source-device-independent quantum random number generator|On the Cover
Lang Li, Minglu Cai, Tao Wang, Zicong Tan, Peng Huang, Kan Wu, and Guihua Zeng
Quantum resources offer intrinsic randomness that is valuable for applications such as cryptography, scientific simulation, and computing. Silicon-based photonics chips present an excellent platform for the cost-effective deployment of next-generation quantum systems on a large scale, even at room temperature. Nevertheless, the potential susceptibility of these chips to hacker control poses a challenge in ensuring security for on-chip quantum random number generation, which is crucial for enabling extensive utilization of quantum resources. Here, we introduce and implement an on-chip source-device-independent quantum random number generator (SDI-QRNG). The randomness of this generator is achieved through distortion-free on-chip detection of quantum resources, effectively eliminating classical noise interference. The security of the system is ensured by employing on-chip criteria for estimating security entropy in a practical chip environment. By incorporating a photoelectric package, the SDI-QRNG chip achieves a secure bit rate of 146.2 Mbps and a bare chip rate of 248.47 Gbps, with all extracted secure bits successfully passing the randomness test. Our experimental demonstration of this chip-level SDI-QRNG shows significant advantages in practical applications, paving the way for the widespread and cost-effective implementation of room-temperature secure QRNG, which marks a milestone in the field of QRNG chips. Quantum resources offer intrinsic randomness that is valuable for applications such as cryptography, scientific simulation, and computing. Silicon-based photonics chips present an excellent platform for the cost-effective deployment of next-generation quantum systems on a large scale, even at room temperature. Nevertheless, the potential susceptibility of these chips to hacker control poses a challenge in ensuring security for on-chip quantum random number generation, which is crucial for enabling extensive utilization of quantum resources. Here, we introduce and implement an on-chip source-device-independent quantum random number generator (SDI-QRNG). The randomness of this generator is achieved through distortion-free on-chip detection of quantum resources, effectively eliminating classical noise interference. The security of the system is ensured by employing on-chip criteria for estimating security entropy in a practical chip environment. By incorporating a photoelectric package, the SDI-QRNG chip achieves a secure bit rate of 146.2 Mbps and a bare chip rate of 248.47 Gbps, with all extracted secure bits successfully passing the randomness test. Our experimental demonstration of this chip-level SDI-QRNG shows significant advantages in practical applications, paving the way for the widespread and cost-effective implementation of room-temperature secure QRNG, which marks a milestone in the field of QRNG chips.
Photonics Research
- Publication Date: Jun. 05, 2024
- Vol. 12, Issue 7, 1379 (2024)
Experimental demonstration of a quantum downstream access network in continuous variable quantum key distribution with a local local oscillator
Dengke Qi, Xiangyu Wang, Zhenghua Li, Jiayu Ma, Ziyang Chen, Yueming Lu, and Song Yu
Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers, including quantum computation, communication, and others. Unlike traditional communication networks, quantum networks utilize quantum bits rather than classical bits to store and transmit information. Quantum key distribution (QKD) relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key, thereby ensuring the security of data transmission. In this work, we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal distribution. Based on this structure, we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local oscillator. In contrast to point-to-point continuous variable QKD, the network architecture reevaluates the security of each user and accounts for it accordingly, and each user has a lower tolerance for excess noise as the overall network expands with more users. Hence, the feasibility of the experiment is based on the analysis of the theoretical model, noise analysis, and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess noise. The results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps, 535 kbps, 522.5 kbps, and 512.5 kbps under a transmission distance of 10 km, respectively, with the finite-size block of 1×108. This not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks. Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers, including quantum computation, communication, and others. Unlike traditional communication networks, quantum networks utilize quantum bits rather than classical bits to store and transmit information. Quantum key distribution (QKD) relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key, thereby ensuring the security of data transmission. In this work, we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal distribution. Based on this structure, we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local oscillator. In contrast to point-to-point continuous variable QKD, the network architecture reevaluates the security of each user and accounts for it accordingly, and each user has a lower tolerance for excess noise as the overall network expands with more users. Hence, the feasibility of the experiment is based on the analysis of the theoretical model, noise analysis, and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess noise. The results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps, 535 kbps, 522.5 kbps, and 512.5 kbps under a transmission distance of 10 km, respectively, with the finite-size block of 1×108. This not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks.
Photonics Research
- Publication Date: May. 31, 2024
- Vol. 12, Issue 6, 1262 (2024)
Picotesla fiberized diamond-based AC magnetometer
Shao-Chun Zhang, Yong Liu, Long-Kun Shan, Xue-Dong Gao, Jia-Qi Geng, Cui Yu, Yang Dong, Xiang-Dong Chen, Guang-Can Guo, and Fang-Wen Sun
Portable quantum sensors are crucial for developing practical quantum sensing and metrology applications. Fiberized nitrogen-vacancy (NV) centers in diamonds have emerged as one of the most promising candidates for compact quantum sensors. Nevertheless, due to the difficulty of coherently controlling the ensemble spin and noise suppression in a large volume, it often faces problems such as reduced sensitivity and narrowed bandwidth in integrated lensless applications. Here, we propose a fluorescence signal treatment method for NV spin ensemble manipulation by the exponential fitting of spin polarization processes, instead of integrating the photon emission. This enables spin state readout with a high signal-to-noise ratio and applies to the pulse sensing protocols for large-volume NV spins. Based on this, we further developed a fiberized diamond-based AC magnetometer. With an XY8-N dynamical decoupling pulse sequence, we demonstrated a T2-limited sensitivity of 8 pT/Hz and T1-limited frequency resolution of 90 Hz over a wide frequency band from 100 kHz to 3 MHz. This integrated diamond sensor leverages quantum coherence to achieve enhanced sensitivity in detecting AC magnetic fields, making it suitable for implementation in a compact and portable endoscopic sensor. Portable quantum sensors are crucial for developing practical quantum sensing and metrology applications. Fiberized nitrogen-vacancy (NV) centers in diamonds have emerged as one of the most promising candidates for compact quantum sensors. Nevertheless, due to the difficulty of coherently controlling the ensemble spin and noise suppression in a large volume, it often faces problems such as reduced sensitivity and narrowed bandwidth in integrated lensless applications. Here, we propose a fluorescence signal treatment method for NV spin ensemble manipulation by the exponential fitting of spin polarization processes, instead of integrating the photon emission. This enables spin state readout with a high signal-to-noise ratio and applies to the pulse sensing protocols for large-volume NV spins. Based on this, we further developed a fiberized diamond-based AC magnetometer. With an XY8-N dynamical decoupling pulse sequence, we demonstrated a T2-limited sensitivity of 8 pT/Hz and T1-limited frequency resolution of 90 Hz over a wide frequency band from 100 kHz to 3 MHz. This integrated diamond sensor leverages quantum coherence to achieve enhanced sensitivity in detecting AC magnetic fields, making it suitable for implementation in a compact and portable endoscopic sensor.
Photonics Research
- Publication Date: May. 31, 2024
- Vol. 12, Issue 6, 1250 (2024)
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