Advanced quantum technologies最新文献

{"title":"Entanglement in Quantum Dots: Insights from Dynamic Susceptibility and Quantum Fisher Information","authors":"Jahanfar Abouie, Daryoosh Vashaee","doi":"10.1002/qute.202400117","DOIUrl":"10.1002/qute.202400117","url":null,"abstract":"<p>This study investigates the entanglement properties of quantum dots (QDs) under a universal Hamiltonian where the Coulomb interaction between particles (electrons or holes) decouples into charging energy and exchange coupling terms. Although this formalism typically decouples the charge and spin components, confinement-induced energy splitting can induce unexpected entanglement within the system. By analyzing the dynamic susceptibility and quantum Fisher information (QFI), significant behaviors are uncovered influenced by exchange constants, temperature variations, and confinement effects. In QDs with Ising exchange interactions, far below the Stoner instability (SI) point, where the QD is in a disordered paramagnetic phase, temperature reductions lead to decreased entanglement, challenging conventional expectations. These findings demonstrate that for QDs with small exchange interactions, the responses of easy-plane (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>z</mi>\u0000 </msub>\u0000 <mo><</mo>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>⊥</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>${J}_z < {J}_ bot $</annotation>\u0000 </semantics></math>) and easy-axis (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>z</mi>\u0000 </msub>\u0000 <mo>></mo>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>⊥</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>${J}_z > {J}_ bot $</annotation>\u0000 </semantics></math>) configurations are similar, with increased anisotropy broadening susceptibility and shifting its maximum to higher frequencies. For large exchange interactions, the susceptibility differences between easy-plane and easy-axis QDs become significant, with easy-plane QDs exhibiting a higher susceptibility magnitude. Additionally, the study reveals that temperature variations affect the dynamic response functions differently in easy-axis and easy-plane QDs. In easy-plane QDs, QFI consistently decreases with increasing temperature, whereas in easy-axis QDs, QFI behavior is highly dependent on the strengths of <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>z</mi>\u0000 </msub>\u0000 <annotation>${J}_z$</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>⊥</mi>\u0000 </msub>\u0000 <annotation>${J}_ bo","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 9","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202400117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718869","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}

{"title":"Back Cover: Photon Number Splitting Attack – Proposal and Analysis of an Experimental Scheme (Adv. Quantum Technol. 7/2024)","authors":"Ariel Ashkenazy,&nbsp;Yuval Idan,&nbsp;Dor Korn,&nbsp;Dror Fixler,&nbsp;Barak Dayan,&nbsp;Eliahu Cohen","doi":"10.1002/qute.202470019","DOIUrl":"https://doi.org/10.1002/qute.202470019","url":null,"abstract":"<p>Depicted is a novel setup for realizing the photon number splitting (PNS) attack with current-day technology, namely, using the single-photon Raman interaction. In article number 2300437, Eliahu Cohen and co-workers analyze the amount of information which the eavesdropper (Eve) can obtain using this physical realization of PNS, concluding that while part of the secret key is at risk when weak coherent states are used, there is still a price for Eve to pay in terms of the induced noise. This stresses the importance of proper countermeasures.\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 7","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202470019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141597181","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}

{"title":"Issue Information (Adv. Quantum Technol. 7/2024)","authors":"","doi":"10.1002/qute.202470018","DOIUrl":"https://doi.org/10.1002/qute.202470018","url":null,"abstract":"","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 7","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202470018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141597182","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}

{"title":"Front Cover: Robust Topological Feature against Non-Hermiticity in Jaynes–Cummings Model (Adv. Quantum Technol. 7/2024)","authors":"Zu-Jian Ying","doi":"10.1002/qute.202470017","DOIUrl":"https://doi.org/10.1002/qute.202470017","url":null,"abstract":"<p>Quantum coherence suffers from environmental influence but the topological feature may not. In article number 2400053, Zu-Jian Ying rigorously shows that the topological feature manifested by the fundamental Jaynes–Cummings model of light–matter interaction is robust against a general non-Hermiticity induced by dissipation and decay rates. The non-Hermiticity only tilts the spin winding plane, while the winding number is preserved. Several revealed properties may be useful for designing topological quantum devices.\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 7","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202470017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141596977","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}

{"title":"Review of Biphoton Sources Based on the Double-\u0000 \u0000 Λ\u0000 $Lambda$\u0000 Spontaneous Four-Wave Mixing Process","authors":"Jia-Mou Chen,&nbsp;Thorsten Peters,&nbsp;Pei-Hsuan Hsieh,&nbsp;Ite A. Yu","doi":"10.1002/qute.202400138","DOIUrl":"10.1002/qute.202400138","url":null,"abstract":"<p>This review article focuses on biphoton sources based on the double-<span></span><math>\u0000 <semantics>\u0000 <mi>Λ</mi>\u0000 <annotation>$Lambda$</annotation>\u0000 </semantics></math> spontaneous four-wave mixing (SFWM) process in laser-cooled as well as room-temperature or hot atomic ensembles. These biphoton sources have the advantage of providing stable frequencies, ultranarrow linewidths, and a tunability of the temporal biphoton width of more than one order of magnitude for high-bandwidth applications. Therefore, the generated photons can be efficiently interfaced to, e.g., atomic quantum memories. In contrast, solid-state biphoton sources typically require assistance by an optical cavity to operate at narrow linewidth that limits the tunability of the temporal width of the biphotons. Present state-of-the-art double-<span></span><math>\u0000 <semantics>\u0000 <mi>Λ</mi>\u0000 <annotation>$Lambda$</annotation>\u0000 </semantics></math> SFWM biphoton sources can achieve one of the following results: a spectral linewidth of 50 kHz (290 kHz) or a temporal width of 13 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>μ</mi>\u0000 <mi>s</mi>\u0000 </mrow>\u0000 <annotation>$umu {rm s}$</annotation>\u0000 </semantics></math> (580 ns) with cold (hot) atoms, a detection rate of about 7<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>×</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>3</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$times 10^3$</annotation>\u0000 </semantics></math> cps, and a generation rate of <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>7</mn>\u0000 </msup>\u0000 <annotation>$10^7$</annotation>\u0000 </semantics></math> cps at a duty cycle of 0.4% or of <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>5</mn>\u0000 </msup>\u0000 <annotation>$10^5$</annotation>\u0000 </semantics></math> cps in the steady state. The theoretical background of these biphoton sources, experimental implementations with cold and hot atoms, and progress over the years, will be illustrated.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 8","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202400138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613987","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}

{"title":"Epitaxial Growth of Nano-Sized Pb Islands on SrTiO3 Substrate: Competition Between Electron Correlation and Enhanced Superconductivity","authors":"Zhibin Shao,&nbsp;Haigen Sun,&nbsp;Yan Cao,&nbsp;Zongyuan Zhang,&nbsp;Shaojian Li,&nbsp;Xin Zhang,&nbsp;Qi Bian,&nbsp;Habakubaho Gedeon,&nbsp;Hui Yuan,&nbsp;Minghu Pan","doi":"10.1002/qute.202300405","DOIUrl":"10.1002/qute.202300405","url":null,"abstract":"<p>The discovery of the interface-enhanced superconductivity in the single-layer film of FeSe epitaxially grown on SrTiO₃ substrates has triggered a flurry of activity in the field of superconductivity. It raised the hope to find more conventional high transition temperature (T_c) superconductors that are purely driven by the electron-phonon interaction at ambient pressure. Here the epitaxial growth of the Pb nano-sized islands on SrTiO₃ (001) substrates with the island volumes ranging from 286 to 4945 nm³ is reported by molecular beam epitaxy, followed by systematic scanning tunneling microscopic/spectroscopic (STM/S) investigation. The observed STS gap for the nanoscale islands highly dependent on the volumes of nano-sized islands, can be divided into three regions. By performing a detailed spectroscopic investigation, it is founded that superconductivity in the volume above 3700 nm³ (Region I) has a zero temperature energy gap (Δ(0)) and T_c of 6.8 meV and 9.8 K obtained by BCS fitting, showing the largely-enhanced Δ and slightly-increased T_c by comparing to the bulk Pb (1.4 meV and 7.2 K). As the volume in the range from 1300 to 3700 nm³ (Region II), a large Coulomb gap induced by electron correlation emerged and shows a volume-dependent behavior, suggesting the reduced size can enhance electron correlation in Pb islands. As the volume decreases down to Region III, enhanced electron correlation and Coulomb gap become more dominant and superconductivity is totally suppressed. The experiment reveals that an electron-electron interaction in nano-sized Pb islands can be significantly enhanced by reducing the island sizes and suppresses the superconductivity, thus demonstrates a competition between superconductivity and electron correlation as the volume varies.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 10","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567530","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":"Zeptosecond-Scale Single-Photon Gyroscope","authors":"Fabrizio Sgobba,&nbsp;Danilo Triggiani,&nbsp;Vincenzo Tamma,&nbsp;Paolo De Natale,&nbsp;Gianluca Gagliardi,&nbsp;Saverio Avino,&nbsp;Luigi Santamaria Amato","doi":"10.1002/qute.202400166","DOIUrl":"10.1002/qute.202400166","url":null,"abstract":"<p>This work presents an all-fiber telecom-range optical gyroscope employing a spontaneous parametric down conversion crystal to produce ultra-low intensity thermal light by tracing-out one of the heralded photons. The prototype exhibits a detection limit on photon delay measurements of 249 zs over a 72 s averaging time and 26 zs in differential delay measurements at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>t</mi>\u0000 <mo>=</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>4</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$t=10^4$</annotation>\u0000 </semantics></math> s averaging. The detection scheme proves to be the most resource-efficient possible, saturating <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 <mn>99.5</mn>\u0000 <mo>%</mo>\u0000 </mrow>\u0000 <annotation>$&amp;gt;99.5%$</annotation>\u0000 </semantics></math> of the Cramér–Rao bound. These results are groundbreaking in the context of low-photon regime quantum metrology, paving the way to novel experimental configurations to bridge quantum optics with special or general relativity.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 9","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202400166","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567528","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}

{"title":"Quadratic Speed-ups in Quantum Kernelized Binary Classification","authors":"Jungyun Lee,&nbsp;Daniel K. Park","doi":"10.1002/qute.202400126","DOIUrl":"10.1002/qute.202400126","url":null,"abstract":"<p>Classification is at the core of data-driven prediction and decision-making, representing a fundamental task in supervised machine learning. Recently, several quantum machine learning algorithms that use quantum kernels as a measure of similarities between data have emerged to perform binary classification on datasets encoded as quantum states. The potential advantages of quantum kernels arise from the ability of quantum computers to construct kernels that are more effective than their classical counterparts in capturing patterns in data or computing kernels more efficiently. However, existing quantum kernel-based classification algorithms do not harness the capability of having data samples in quantum superposition for additional enhancements. This work demonstrates how such capability can be leveraged in quantum kernelized binary classifiers (QKCs) through Quantum Amplitude Estimation (QAE) for quadratic speed-up. Additionally, new quantum circuits are proposed for the QKCs in which the number of qubits is reduced by one, and the circuit depth is reduced linearly with respect to the number of sample data. The quadratic speed-up over previous methods is verified through numerical simulations on the Iris dataset.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 8","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202400126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567527","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}

{"title":"Quantum Battery in the Heisenberg Spin Chain Models with Dzyaloshinskii-Moriya Interaction","authors":"Xiang-Long Zhang,&nbsp;Xue-Ke Song,&nbsp;Dong Wang","doi":"10.1002/qute.202400114","DOIUrl":"10.1002/qute.202400114","url":null,"abstract":"<p>Quantum battery (QB) is an energy storage and extraction device conforming to the principles of quantum mechanics. In this study, the characteristics of QBs are considered for the Heisenberg spin chain models in the absence and presence of Dzyaloshinskii-Moriya (DM) interaction. The results show that the DM interaction can enhance the ergotropy and power of QBs, which shows the collective charging can outperform parallel charging regarding QB's performance. Besides, it turns out that first-order coherence is a crucial quantum resource during charging, while quantum steering between the cells is not conducive to the energy storage of QBs. The investigations offer insight into the properties of QBs with Heisenberg spin chain models with DM interaction and facilitate us to acquire the performance in the framework of realistic quantum batteries.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 9","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567525","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":"Observation of Room Temperature Exchange Cavity Magnon-Polaritons in Metallic Thin Films","authors":"Mawgan A. Smith,&nbsp;Adam L. Lafferty,&nbsp;Alban Joseph,&nbsp;Matthew R. McMaster,&nbsp;Jade N. Scott,&nbsp;William R. Hendren,&nbsp;Robert M. Bowman,&nbsp;Martin P. Weides,&nbsp;Rair Macêdo","doi":"10.1002/qute.202300420","DOIUrl":"10.1002/qute.202300420","url":null,"abstract":"<p>Cavity magnonics has become an intriguing field due to its potential to enable next-generation technologies centered around controlling information exchange in hybrid resonant systems. Investigating the tunability of magnon-photon coupling is key to advancing the field. Here, the observation of coupling between the first order magnon mode in a metallic thin film with a cavity photon mode is reported. An electromagnetic perturbation theory that takes account of perpendicular standing spin waves and their respective dissipation is utilized to estimate the coupling strength. The metallic thin film exhibits notably lower dissipation for the higher-order magnon mode, which is not observed in a thin film magnetic insulator. As such, and given that metallic Kittel magnons typically exhibit lower coherence times than their insulator counterparts, the excitation and coupling to specific higher order modes could lengthen these times compared to previous observations, which may be useful for future integration into quantum devices.</p>","PeriodicalId":72073,"journal":{"name":"Advanced quantum technologies","volume":"7 8","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/qute.202300420","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567534","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}