Samira Elghaayda, Asad Ali, Saif Al-Kuwari, Artur Czerwinski, Mostafa Mansour, Saeed Haddadi
{"title":"Performance of a Superconducting Quantum Battery","authors":"Samira Elghaayda, Asad Ali, Saif Al-Kuwari, Artur Czerwinski, Mostafa Mansour, Saeed Haddadi","doi":"10.1002/qute.202400651","DOIUrl":"10.1002/qute.202400651","url":null,"abstract":"<p>Finding a quantum battery model that demonstrates a quantum advantage while remaining feasible for experimental production is a considerable challenge. Here, a superconducting quantum battery (SQB) model that exhibits such an advantage is introduced. The model consists of two coupled superconducting qubits that interact during the unitary charging process while remaining in equilibrium with a thermal reservoir. First, the model is described, evidence of the quantum advantage is provided, and then the fabrication process of the battery is discussed using superconducting qubits. Analytical expressions for the ergotropy, instantaneous power, and capacity of the SQB, as well as their connection to quantum coherence are derived. It is demonstrated that leveraging the collective effects of Josephson energies and the coupling energy between qubits allows for optimization, resulting in improved energy redistribution and a significant enhancement in charging efficiency. This work highlights the complexities of tuning system parameters, which increase the potential for work extraction from the SQB, providing a deeper understanding of the charging mechanisms involved. These findings can be applied to superconducting quantum circuit battery architectures, underscoring the feasibility of efficient energy storage in these systems. These results pave the way for proposals of new superconducting devices, emphasizing their potential for efficient energy storage.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 9","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://advanced.onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202400651","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Penglong Li, Xin Li, Xiaojiang Wang, Zhuowen Chen, Huan Fei Wen, Zongmin Ma, Jun Tang, Jun Liu
{"title":"Temperature Detection in Individual Brown Adipocytes with Nitrogen-Vacancy Ensemble in Diamond","authors":"Penglong Li, Xin Li, Xiaojiang Wang, Zhuowen Chen, Huan Fei Wen, Zongmin Ma, Jun Tang, Jun Liu","doi":"10.1002/qute.202400664","DOIUrl":"10.1002/qute.202400664","url":null,"abstract":"<p>Brown adipocytes participate in regulating body temperature through heat production, and temperature measurement is essential for understanding their thermogenesis mechanism. Although many advanced techniques have been proposed, achieving non-invasive temperature detection at the single-cell level still presents significant challenges. Here, a method is developed to measure the extracellular temperature of cultured brown adipocytes using nitrogen-vacancy ensemble in diamond. The measurement principle is based on the resonance frequency of nitrogen-vacancy centers changing with temperature when heat flows into the diamond integrated with nitrogen-vacancy ensemble. This method enables precise imaging the temperature distribution differences on individual cell surfaces with a temperature sensitivity of 35 mK Hz<sup>−1/2</sup>. With this method, a temperature increase of over 0.5 °C is observed in brown adipocytes stimulated by mitochondrial uncoupling agents. This result demonstrates that NV ensemble is a promising tool for studying thermogenesis in brown adipocytes and provides new research approaches for non-invasive cell temperature measurements.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 9","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yang Yang, Qin-Wei Zhang, Xue-Lin Zhai, Xiang-Yu Zeng, Shuai Zhang, Jia-Qiang Zhao, Mei-Jiao Wang, Chang Liu, Xia Liu, Lian-Zhen Cao
{"title":"Quantum Teleportation of Photon–Photon Diagonal Block Operations","authors":"Yang Yang, Qin-Wei Zhang, Xue-Lin Zhai, Xiang-Yu Zeng, Shuai Zhang, Jia-Qiang Zhao, Mei-Jiao Wang, Chang Liu, Xia Liu, Lian-Zhen Cao","doi":"10.1002/qute.202400662","DOIUrl":"10.1002/qute.202400662","url":null,"abstract":"<p>Teleportation of an unknown quantum operation, implementing a nonlocal gate on two distant particles, constitutes a fundamental component in quantum networks and distributed large-scale quantum computers. In this study, it is realized that the experimental demonstration of teleporting photon-photon diagonal block operations. Assisted by two previously shared entangled photons, a local photon-photon diagonal block operation is transferred to its corresponding nonlocal gate and the protocol is able to realize a nonlocal photon–photon operation with diagonal block forms containing two unknown single-qubit unitary operations. In experiment, two nonlocal diagonal block operations are successfully implemented on two separated independent single photons: the controlled-NOT (CNOT) gate and the controlled-Z (CZ) gate. To characterize the performance of the nonlocal photon–photon operations, the quantum teleported process fidelity is estimated. Additionally, the entangling capability of teleported photon–photon CNOT gate is verified. These results provide an approach to implement a unknown nonlocal photon–photon diagonal block gate and may have broad applications in distributed quantum information processing including quantum communication and quantum computation.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 9","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantum-enhanced NMR Co-Magnetometers Based on Encounter-propagating Pump Beams","authors":"Tengyue Wang, Jianli Li, Zhanchao Liu, Jinpeng Peng, Zekun Wu, Xuelei Wang","doi":"10.1002/qute.202400625","DOIUrl":"10.1002/qute.202400625","url":null,"abstract":"<p>Nuclear Magnetic Resonance (NMR) co-magnetometers are advanced quantum sensors capable of measuring angular velocity for inertial navigation. Within the Rb-Xe atomic ensemble, Rb atoms absorb polarized light, decreasing electron spin polarization as the light travels greater distances. This attenuation causes a gradient in Rb spin polarization that severely affects atomic relaxation characteristics and degrades NMR sensors’ performance. Considering atomic diffusion motion, a theoretical simulation model is developed and the spatial distribution of electron spin polarization under the encounter-propagating dual-beam configuration is simulated. The simulation results demonstrate that the proposed dual-beam scheme achieves a more uniform distribution of electron polarization within the atomic vapor cell. Experiments reveal an 18% enhancement in <sup>129</sup>Xe nuclear spin polarization using the dual-beam scheme compared to the conventional single-beam. Through the Fermi contact interaction between optically pumped Rb and Xe atoms, a more uniform spatial distribution of Rb spin polarization reduces the gradient relaxation of Xe atoms and its depolarization effects, thereby significantly enhancing the macroscopic Xe spin polarization and the signal-to-noise ratio (SNR) of NMR sensors. This study presents a new method for improving atomic polarization, significantly enhancing the performance of quantum sensors.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 9","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Walid El Maouaki, Alberto Marchisio, Taoufik Said, Muhammad Shafique, Mohamed Bennai
{"title":"Designing Robust Quantum Neural Networks via Optimized Circuit Metrics","authors":"Walid El Maouaki, Alberto Marchisio, Taoufik Said, Muhammad Shafique, Mohamed Bennai","doi":"10.1002/qute.202400601","DOIUrl":"10.1002/qute.202400601","url":null,"abstract":"<p>In this study, the robustness of Quanvolutional Neural Networks (QuNNs) is investigated in comparison to their classical counterparts, Convolutional Neural Networks (CNNs), against two adversarial attacks: the Fast Gradient Sign Method (FGSM) and the Projected Gradient Descent (PGD), for the image classification task on both the Modified National Institute of Standards and Technology (MNIST) and Fashion-MNIST (FMNIST) datasets. To enhance the robustness of QuNNs, a novel methodology is developed that utilizes three quantum circuit metrics: expressibility, entanglement capability, and controlled rotation gate selection. This analysis shows that these metrics significantly influence data representation within the Hilbert space, thereby directly affecting QuNN robustness. It is rigorously established that circuits with higher expressibility and lower entanglement capability generally exhibit enhanced robustness under adversarial conditions, particularly at low-spectrum perturbation strengths where most attacks occur. Furthermore, these findings challenge the prevailing assumption that expressibility alone dictates circuit robustness; instead, it is demonstrated that the inclusion of controlled rotation gates around the Z-axis generally enhances the resilience of QuNNs. These results demonstrate that QuNNs exhibit up to 60% greater robustness on the MNIST dataset and 40% on the Fashion-MNIST dataset compared to CNNs. Collectively, this work elucidates the relationship between quantum circuit metrics and robust data feature extraction, advancing the field by improving the adversarial robustness of QuNNs.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 6","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PT\u0000 $mathcal {PT}$\u0000 -Symmetric Quantum Rabi Model: Solutions and Exceptional Points","authors":"Jiong Li, Yi-Cheng Wang, Li-Wei Duan, Qing-Hu Chen","doi":"10.1002/qute.202400609","DOIUrl":"10.1002/qute.202400609","url":null,"abstract":"<p>The <span></span><math>\u0000 <semantics>\u0000 <mi>PT</mi>\u0000 <annotation>$mathcal {PT}$</annotation>\u0000 </semantics></math>-symmetric non-Hermitian quantum Rabi model (QRM) with imaginary coupling is solved using the Bogoliubov operators approach. A transcendental function responsible for the exact solutions is derived, with its zeros yielding the regular spectrum. Two types of intersections: the exceptional points (EPs), which are well-studied in the non-Hermitian system; and another arising from doubly degenerate states due to the conserved QRM parity, which is well-known in the Hermitian QRM, are found. These intersections are identified through this transcendental function. EPs emerge between pairs of adjacent excited energy levels, shifting toward lower coupling strengths as energy levels increase, and can also be predicted by a generalized rotating-wave approximation approach. The fidelity susceptibility diverges to negative infinity at the EPs, consistent with recent findings in non-Hermitian systems, while it diverges to positive infinity at the doubly degenerate points. The EPs are further confirmed by the vanishing c-product in the biorthogonal basis.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"8 6","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}