Pub Date : 2024-08-06DOI: 10.1103/physrevapplied.22.024015
Vladimir M. Krasnov
Current-biased Josephson junctions can act as detectors of electromagnetic radiation. At optimal conditions, their sensitivity is limited by fluctuations causing stochastic switching from the superconducting to the resistive state. This work provides a quantitative description of a stochastic switching current detector, based on an underdamped Josephson junction. It is shown that activation of a Josephson plasma resonance can greatly enhance the detector responsivity in proportion to the quality factor of the junction. The ways of tuning the detector for achieving optimal operation are discussed. For realistic parameters of // tunnel junctions, the sensitivity and noise-equivalent power (NEP) can reach values of (V/W) and (), respectively. These outstanding characteristics facilitate both bolometric and single-photon detection in microwave and terahertz ranges.
{"title":"Resonant switching current detector based on underdamped Josephson junctions","authors":"Vladimir M. Krasnov","doi":"10.1103/physrevapplied.22.024015","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024015","url":null,"abstract":"Current-biased Josephson junctions can act as detectors of electromagnetic radiation. At optimal conditions, their sensitivity is limited by fluctuations causing stochastic switching from the superconducting to the resistive state. This work provides a quantitative description of a stochastic switching current detector, based on an underdamped Josephson junction. It is shown that activation of a Josephson plasma resonance can greatly enhance the detector responsivity in proportion to the quality factor of the junction. The ways of tuning the detector for achieving optimal operation are discussed. For realistic parameters of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Nb</mi></math>/<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mrow><mi>Al</mi><mi mathvariant=\"normal\">O</mi></mrow><mi>x</mi></msub></math>/<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Nb</mi></math> tunnel junctions, the sensitivity and noise-equivalent power (NEP) can reach values of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>S</mi><mo>≃</mo><mspace width=\"0.2em\"></mspace><mn>5</mn><mo>×</mo><msup><mn>10</mn><mn>12</mn></msup></math> (V/W) and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>NEP</mi><mo>≃</mo><mspace width=\"0.2em\"></mspace><mn>2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>23</mn></mrow></msup></math> (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>WHz</mi><mrow><mo>−</mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math>), respectively. These outstanding characteristics facilitate both bolometric and single-photon detection in microwave and terahertz ranges.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"5 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1103/physrevapplied.22.024014
P. Michel, L. Lancia, A. Oudin, E. Kur, C. Riconda, K. Ou, V.M. Perez-Ramirez, J. Lee, M.R. Edwards
Acousto-optics consists of launching acoustic waves in a medium (usually a crystal) in order to modulate its refractive index and create a tunable optical grating. In this article, we present the theoretical basis of an alternative scheme to generate acousto-optics in a gas, where the acoustic waves are initiated by the localized absorption (and thus gas heating) of spatially modulated UV light, as was demonstrated by Michine and Yoneda [Commun. Phys. 3, 24 (2020)]. We identify the chemical reactions initiated by the absorption of UV light via the photodissociation of ozone molecules present in the gas, and calculate the resulting temperature increase in the gas as a function of space and time. Solving the Euler fluid equations shows that the modulated, isochoric heating initiates a mixed acoustic-entropy wave in the gas, whose high-amplitude density (and thus refractive index) modulation can be used to manipulate a high-power laser. We calculate that diffraction efficiencies near 100% can be obtained using only a few millimeters of gas containing a few percent ozone fraction at room temperature, with UV fluences of less than 100 —consistent with the experimental measurements. Our analysis suggests possible ways to optimize the diffraction efficiency by changing the buffer gas composition. Gases have optics damage thresholds 2–3 orders of magnitude beyond those of solids; these optical elements should therefore be able to manipulate kilojoule-class lasers.
{"title":"Photochemically induced acousto-optics in gases","authors":"P. Michel, L. Lancia, A. Oudin, E. Kur, C. Riconda, K. Ou, V.M. Perez-Ramirez, J. Lee, M.R. Edwards","doi":"10.1103/physrevapplied.22.024014","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024014","url":null,"abstract":"Acousto-optics consists of launching acoustic waves in a medium (usually a crystal) in order to modulate its refractive index and create a tunable optical grating. In this article, we present the theoretical basis of an alternative scheme to generate acousto-optics in a gas, where the acoustic waves are initiated by the localized absorption (and thus gas heating) of spatially modulated UV light, as was demonstrated by Michine and Yoneda [Commun. Phys. 3, 24 (2020)]. We identify the chemical reactions initiated by the absorption of UV light via the photodissociation of ozone molecules present in the gas, and calculate the resulting temperature increase in the gas as a function of space and time. Solving the Euler fluid equations shows that the modulated, isochoric heating initiates a mixed acoustic-entropy wave in the gas, whose high-amplitude density (and thus refractive index) modulation can be used to manipulate a high-power laser. We calculate that diffraction efficiencies near 100% can be obtained using only a few millimeters of gas containing a few percent ozone fraction at room temperature, with UV fluences of less than 100 <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mrow><mi>mJ</mi><mo>/</mo><mi>cm</mi></mrow></mrow><mn>2</mn></msup></math>—consistent with the experimental measurements. Our analysis suggests possible ways to optimize the diffraction efficiency by changing the buffer gas composition. Gases have optics damage thresholds 2–3 orders of magnitude beyond those of solids; these optical elements should therefore be able to manipulate kilojoule-class lasers.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"15 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.1103/physrevapplied.22.024009
Yapeng Wang, Yongcheng Ding, Francisco Andrés Cárdenas-López, Xi Chen
Solving optimization problems using variational algorithms stands out as a crucial application for noisy intermediate-scale devices. Instead of constructing gate-based quantum computers, our focus centers on designing variational quantum algorithms within the analog paradigm. This involves optimizing parameters that directly control pulses, driving quantum states toward target states without the necessity to compile a quantum circuit. In this work, we introduce pulse-based variational quantum optimization (PBVQO) as a hardware-level framework. We illustrate the framework by optimizing external fluxes on superconducting quantum interference devices, effectively driving the wave function of this specific quantum architecture to the ground state of an encoded problem Hamiltonian. Given that the performance of variational algorithms relies heavily on appropriate initial parameters, we introduce a global optimizer as a metalearning technique to tackle a simple problem. The synergy between PBVQO and metalearning provides an advantage over conventional gate-based variational algorithms.
{"title":"Pulse-based variational quantum optimization and metalearning in superconducting circuits","authors":"Yapeng Wang, Yongcheng Ding, Francisco Andrés Cárdenas-López, Xi Chen","doi":"10.1103/physrevapplied.22.024009","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024009","url":null,"abstract":"Solving optimization problems using variational algorithms stands out as a crucial application for noisy intermediate-scale devices. Instead of constructing gate-based quantum computers, our focus centers on designing variational quantum algorithms within the analog paradigm. This involves optimizing parameters that directly control pulses, driving quantum states toward target states without the necessity to compile a quantum circuit. In this work, we introduce pulse-based variational quantum optimization (PBVQO) as a hardware-level framework. We illustrate the framework by optimizing external fluxes on superconducting quantum interference devices, effectively driving the wave function of this specific quantum architecture to the ground state of an encoded problem Hamiltonian. Given that the performance of variational algorithms relies heavily on appropriate initial parameters, we introduce a global optimizer as a metalearning technique to tackle a simple problem. The synergy between PBVQO and metalearning provides an advantage over conventional gate-based variational algorithms.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"32 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.1103/physrevapplied.22.024011
L. Phuttitarn, B. M. Becker, R. Chinnarasu, T. M. Graham, M. Saffman
We demonstrate qubit-state measurements assisted by a supervised convolutional neural network (CNN) in a neutral-atom quantum processor. We present two CNN architectures for analyzing neutral-atom qubit readout data: a compact five-layer single-qubit CNN architecture and a six-layer multiqubit CNN architecture. We benchmark both architectures against a conventional Gaussian-threshold analysis method. In a sparse array (9- atom separation) which experiences negligible crosstalk, we have observed up to 32% and 56% error reduction for the multiqubit and single-qubit architectures, respectively, as compared to the benchmark. In a tightly spaced array (5- atom separation), which suffers from readout crosstalk, we have observed up to 43% and 32% error reduction in the multiqubit and single-qubit CNN architectures, respectively, as compared to the benchmark. By examining the correlation between the predicted states of neighboring qubits, we have found that the multiqubit CNN architecture reduces the crosstalk correlation by up to 78.5%. This work demonstrates a proof of concept for a CNN network to be implemented as a real-time readout-processing method on a neutral-atom quantum computer, enabling faster readout time and improved fidelity.
{"title":"Enhanced measurement of neutral-atom qubits with machine learning","authors":"L. Phuttitarn, B. M. Becker, R. Chinnarasu, T. M. Graham, M. Saffman","doi":"10.1103/physrevapplied.22.024011","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024011","url":null,"abstract":"We demonstrate qubit-state measurements assisted by a supervised convolutional neural network (CNN) in a neutral-atom quantum processor. We present two CNN architectures for analyzing neutral-atom qubit readout data: a compact five-layer single-qubit CNN architecture and a six-layer multiqubit CNN architecture. We benchmark both architectures against a conventional Gaussian-threshold analysis method. In a sparse array (9-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext fontfamily=\"times\">μ</mtext><mrow><mi mathvariant=\"normal\">m</mi></mrow></math> atom separation) which experiences negligible crosstalk, we have observed up to 32% and 56% error reduction for the multiqubit and single-qubit architectures, respectively, as compared to the benchmark. In a tightly spaced array (5-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext fontfamily=\"times\">μ</mtext><mrow><mi mathvariant=\"normal\">m</mi></mrow></math> atom separation), which suffers from readout crosstalk, we have observed up to 43% and 32% error reduction in the multiqubit and single-qubit CNN architectures, respectively, as compared to the benchmark. By examining the correlation between the predicted states of neighboring qubits, we have found that the multiqubit CNN architecture reduces the crosstalk correlation by up to 78.5%. This work demonstrates a proof of concept for a CNN network to be implemented as a real-time readout-processing method on a neutral-atom quantum computer, enabling faster readout time and improved fidelity.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"5 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.1103/physrevapplied.22.024010
Oscar Kremer, Igor Califrer, Daniel Tandeitnik, Jean Pierre von der Weid, Guilherme Temporão, Thiago Guerreiro
We implement an all-electrical controller for 3D feedback cooling of an optically levitated nanoparticle capable of reaching subkelvin temperatures for the center-of-mass motion. The controller is based on an optimal policy in which state estimation is made by delayed position measurements. The method offers a simplified path for precooling and decoupling the transverse degrees of freedom of the nanoparticle. Numerical simulations show that in an improved setup with quantum limited detection, all three axes can be cooled down to a few-phonon regime.
{"title":"All-electrical cooling of an optically levitated nanoparticle","authors":"Oscar Kremer, Igor Califrer, Daniel Tandeitnik, Jean Pierre von der Weid, Guilherme Temporão, Thiago Guerreiro","doi":"10.1103/physrevapplied.22.024010","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024010","url":null,"abstract":"We implement an all-electrical controller for 3D feedback cooling of an optically levitated nanoparticle capable of reaching subkelvin temperatures for the center-of-mass motion. The controller is based on an optimal policy in which state estimation is made by delayed position measurements. The method offers a simplified path for precooling and decoupling the transverse degrees of freedom of the nanoparticle. Numerical simulations show that in an improved setup with quantum limited detection, all three axes can be cooled down to a few-phonon regime.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"41 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1103/physrevapplied.22.024005
Shuting Hou, Xikui Ma, Chao Ding, Yueheng Du, Mingwen Zhao
The emergence of two-dimensional (2D) hyperbolic materials, characterized by opposite-sign optical conductivities along two orthogonal axes within a specific band (known as the hyperbolic region), opens an avenue for optical device engineering. Broadening the hyperbolic region is essential for cutting-edge photonic applications. In this study, based on a correlation between the hyperbolic region and anisotropic electronic structures, we propose a strategic framework for identifying 2D natural hyperbolic materials (NHMs) with broadband hyperbolicity. Using this framework, we engineered a 2D lattice incorporating p and d orbitals, and discovered a series of 2D NHMs, MYZ (M = ; Y = ; and Z = ). These materials exhibit broadband hyperbolicity that extends from the near-infrared to the visible-light spectrum. We have confirmed the directional propagation of surface plasmon polaritons on these 2D materials based on Maxwell’s equations. Our findings pave the way for future exploration and practical deployment of 2D NHMs in advanced technological applications.
二维（2D）双曲面材料的特点是在特定波段（称为双曲面区域）内沿两个正交轴具有相反的光传导性，这种材料的出现为光学设备工程开辟了一条道路。拓宽双曲区对于尖端光子应用至关重要。在本研究中，基于双曲区与各向异性电子结构之间的关联，我们提出了一种战略框架，用于识别具有宽带双曲性的二维天然双曲材料（NHM）。利用这一框架，我们设计了一个包含 p 和 d 轨道的二维晶格，并发现了一系列二维天然双曲材料 MYZ（M = Co,Pd,Ru,Rh；Y = S,Se,Te；Z = Cl,Br,I）。这些材料表现出从近红外光谱到可见光光谱的宽带双曲性。我们根据麦克斯韦方程证实了表面等离子体极化子在这些二维材料上的定向传播。我们的发现为未来探索和实际部署二维 NHMs 在先进技术应用中的应用铺平了道路。
{"title":"Enhancing the hyperbolic bandwidth in two-dimensional materials via atomic orbital engineering","authors":"Shuting Hou, Xikui Ma, Chao Ding, Yueheng Du, Mingwen Zhao","doi":"10.1103/physrevapplied.22.024005","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024005","url":null,"abstract":"The emergence of two-dimensional (2D) hyperbolic materials, characterized by opposite-sign optical conductivities along two orthogonal axes within a specific band (known as the hyperbolic region), opens an avenue for optical device engineering. Broadening the hyperbolic region is essential for cutting-edge photonic applications. In this study, based on a correlation between the hyperbolic region and anisotropic electronic structures, we propose a strategic framework for identifying 2D natural hyperbolic materials (NHMs) with broadband hyperbolicity. Using this framework, we engineered a 2D lattice incorporating <i>p</i> and <i>d</i> orbitals, and discovered a series of 2D NHMs, <i>MYZ</i> (<i>M</i> = <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Co</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Pd</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Ru</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Rh</mi></math>; <i>Y</i> = <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mi mathvariant=\"normal\">S</mi></mrow></mrow><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Se</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Te</mi></math>; and <i>Z</i> = <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Cl</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mi>Br</mi><mo>,</mo><mspace width=\"0.2em\"></mspace><mrow><mrow><mi mathvariant=\"normal\">I</mi></mrow></mrow></math>). These materials exhibit broadband hyperbolicity that extends from the near-infrared to the visible-light spectrum. We have confirmed the directional propagation of surface plasmon polaritons on these 2D materials based on Maxwell’s equations. Our findings pave the way for future exploration and practical deployment of 2D NHMs in advanced technological applications.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"46 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1103/physrevapplied.22.024004
Shaowei Zhang, Feng Wen, Muhua Zhai, Zheng Li, Huapeng Ye, Hengxi Zhang, Yangxin Gu, Yang Lei, Wei Wang, Yanpeng Zhang, Hongxing Wang
The monolayer graphene-based terahertz (THz) perfect absorber has made significant progress in switchable devices with diverse functionalities. However, existing methods for achieving switchability rely on either multilayered metasurface with complex configurations or complicated patterned metasurfaces. A switchable absorber that switches between n-band and m-band modes (n, m correspond to the number of resonance peaks) using tunable materials is also interesting but has not yet been mentioned. Here, a dynamically switchable multiband perfect absorber with a digital coding graphene metasurface is proposed and demonstrated. By integrating multiple metasurface units with different Fermi levels into a newly generated period, we realize a multiband perfect absorber with a rather simple and straightforward configuration composed of a patterned metasurface. Through introducing a digital coding metasurface into the perfect absorber, we use the digital signals via FPGA (field programmable gate array) to convert n-band into m-band absorption modes. Moreover, the results reveal that the THz perfect absorber, possessing great impedance matching with the free space, has excellent angle tolerance and robustness. Such a perfect absorber offers a flexible tool for selecting THz channels and may pave the way for generation communication.
基于单层石墨烯的太赫兹（THz）完美吸收器在具有各种功能的可切换器件方面取得了重大进展。然而，实现可切换性的现有方法要么依赖于具有复杂配置的多层元表面，要么依赖于复杂的图案元表面。利用可调材料在 n 波段和 m 波段模式（n、m 对应于共振峰的数量）之间切换的可切换吸收器也很有趣，但尚未被提及。在这里，我们提出并展示了一种具有数字编码石墨烯元表面的动态可切换多波段完美吸收器。通过将具有不同费米级的多个元表面单元集成到一个新产生的周期中，我们实现了一种由图案化元表面组成的多波段完美吸收器，其配置相当简单明了。通过在完美吸收器中引入数字编码元表面，我们利用 FPGA（现场可编程门阵列）的数字信号将 n 波段吸收模式转换为 m 波段吸收模式。此外，研究结果表明，太赫兹完美吸收器与自由空间的阻抗匹配度很高，具有出色的角度容限和鲁棒性。这种完美吸收器为选择太赫兹信道提供了灵活的工具，并可能为第六代通信铺平道路。
{"title":"Terahertz dynamic multiband perfect absorber with a digital coding graphene-diamond metasurface","authors":"Shaowei Zhang, Feng Wen, Muhua Zhai, Zheng Li, Huapeng Ye, Hengxi Zhang, Yangxin Gu, Yang Lei, Wei Wang, Yanpeng Zhang, Hongxing Wang","doi":"10.1103/physrevapplied.22.024004","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024004","url":null,"abstract":"The monolayer graphene-based terahertz (THz) perfect absorber has made significant progress in switchable devices with diverse functionalities. However, existing methods for achieving switchability rely on either multilayered metasurface with complex configurations or complicated patterned metasurfaces. A switchable absorber that switches between <i>n</i>-band and <i>m</i>-band modes (<i>n</i>, <i>m</i> correspond to the number of resonance peaks) using tunable materials is also interesting but has not yet been mentioned. Here, a dynamically switchable multiband perfect absorber with a digital coding graphene metasurface is proposed and demonstrated. By integrating multiple metasurface units with different Fermi levels into a newly generated period, we realize a multiband perfect absorber with a rather simple and straightforward configuration composed of a patterned metasurface. Through introducing a digital coding metasurface into the perfect absorber, we use the digital signals via FPGA (field programmable gate array) to convert <i>n</i>-band into <i>m</i>-band absorption modes. Moreover, the results reveal that the THz perfect absorber, possessing great impedance matching with the free space, has excellent angle tolerance and robustness. Such a perfect absorber offers a flexible tool for selecting THz channels and may pave the way for <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>sixth</mi><mo>−</mo></msup></math>generation communication.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"37 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1103/physrevapplied.22.024003
David E. Fernandes, Sylvain Lannebère, Tiago A. Morgado, Mário G. Silveirinha
Motivated by our recent findings in [Phys. Rev. Lett. 128, 013902, 2022], which introduced a new class of electromagnetic bulk materials whose response is similar to conventional semiconductor transistors, here we propose a one-dimensional (1D) version of such materials based on transmission lines coupled with FET isolators. We demonstrate that the response of this 1D system is nonreciprocal and non-Hermitian, analogous to the idealized transistor-metamaterial, and is also characterized by a broken time-reversal symmetry. We analyze the wave propagation in the system and find that the interaction between the eigenmodes can either lead to gain or loss, depending on the propagation distance. Furthermore, it is also shown that the system may be operated at an exceptional point, wherein the response becomes singular, and the power gain is maximized. Finally, we demonstrate that the exceptional point coincides with the point of operation of typical microwave amplifiers, such as the distributed amplifier.
我们最近在[Phys. Rev. Lett. 128, 013902, 2022]中的研究成果介绍了一类新的电磁体材料，其响应类似于传统的半导体晶体管。我们证明，这种一维系统的响应是非互易和非赫米提的，类似于理想化的晶体管-超材料，而且还具有时间反向对称性被打破的特点。我们分析了波在该系统中的传播，发现特征模之间的相互作用会导致增益或损耗，具体取决于传播距离。此外，我们还发现该系统可在一个特殊点上运行，此时响应变得奇异，功率增益达到最大。最后，我们证明该异常点与典型微波放大器（如分布式放大器）的工作点相吻合。
{"title":"Exceptional points in transistor-metamaterial-inspired transmission lines","authors":"David E. Fernandes, Sylvain Lannebère, Tiago A. Morgado, Mário G. Silveirinha","doi":"10.1103/physrevapplied.22.024003","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024003","url":null,"abstract":"Motivated by our recent findings in [Phys. Rev. Lett. 128, 013902, 2022], which introduced a new class of electromagnetic bulk materials whose response is similar to conventional semiconductor transistors, here we propose a one-dimensional (1D) version of such materials based on transmission lines coupled with FET isolators. We demonstrate that the response of this 1D system is nonreciprocal and non-Hermitian, analogous to the idealized transistor-metamaterial, and is also characterized by a broken time-reversal symmetry. We analyze the wave propagation in the system and find that the interaction between the eigenmodes can either lead to gain or loss, depending on the propagation distance. Furthermore, it is also shown that the system may be operated at an exceptional point, wherein the response becomes singular, and the power gain is maximized. Finally, we demonstrate that the exceptional point coincides with the point of operation of typical microwave amplifiers, such as the distributed amplifier.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"298 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical and photoemission measurements were performed on alkali antimonide <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> and <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes in order to determine their energy-band diagrams, elucidate the photoemission pathways, and explore the options for interface engineering in order to reach high quantum efficiencies of the photocathodes. This study is motivated by the recent discovery of optical orientation in <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> and emission of spin-polarized electrons from <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes [V.S. Rusetsky <i>et al.</i>, Phys. Rev. Lett. <b>129</b>, 166802 (2022)]. We have shown that the band gap <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>E</mi><mi>g</mi></msub></math> of <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> at <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>T</mi><mo>=</mo><mn>295</mn></math> K lies within the range of 1.40–1.44 eV. The <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> surface activation by the deposition of <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Cs</mi></math> and <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Sb</mi></math> results in effective electron affinity decrease by approximately 0.37 eV, and in an increase of the quantum efficiency up to 0.2 electrons per incident photon. The analysis of longitudinal energy distribution curves (EDCs) proves that the surface of activated <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes have negative effective electron affinity of approximately <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mo>−</mo><mn>0.1</mn></math> and <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mo>−</mo><mn>0.25</mn></math> eV at <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>T</mi><mo>=</mo><mn>295</mn></math> and 80 K, respectively. EDC measurements under increasing photon energy <math display
我们对碱锑化 Na2KSb 和 Na2KSb/CsxSb 光阴极进行了光学和光发射测量，以确定它们的能带图，阐明光发射途径，并探索界面工程选项，从而实现光阴极的高量子效率。这项研究的动机是最近在 Na2KSb 中发现的光学取向以及 Na2KSb/CsxSb 光阴极发射的自旋极化电子[V.S. Rusetsky 等人，Phys. Rev. Lett.我们已经证明，在 T=295 K 时，Na2KSb 的带隙 Eg 在 1.40-1.44 eV 范围内。通过沉积铯和锑对 Na2KSb 表面进行活化，有效电子亲和力降低了约 0.37 eV，量子效率提高到每入射光子 0.2 个电子。纵向能量分布曲线（EDC）分析表明，活化的 Na2KSb/CsxSb 光阴极表面在 T=295 和 80 K 时的有效电子亲和力分别为负约 -0.1 和 -0.25 eV。在光子能量ℏω不断增加的条件下进行的 EDC 测量表明，光发射途径从表面态在ℏω<Eg 处的光离子化过渡到了ℏω≈Eg 处从传导带底部发射，以及ℏω>Eg 处从传导带中的高动能态发射。与 p-砷化镓（Cs,O）光电阴极相比，在 80 K 条件下测量的 EDC 表明 Na2KSb/CsxSb 光电阴极的光电子发射具有高度的方向性。这一事实以及在 Na2KSb 表面被铯和锑活化的情况下观察到的光致发光强度的显著增加（数量级）表明，与 p-GaAs（Cs，O）光电阴极的非晶态（Cs，O）活化层中的强散射相比，Na2KSb/CsxSb 光电阴极的 "准pitaxial "CsxSb 活化层中的扩散散射相对较弱。
{"title":"Na2KSb/CsxSb interface engineering for high-efficiency photocathodes","authors":"S.A. Rozhkov, V.V. Bakin, V.S. Rusetsky, D.A. Kustov, V.A. Golyashov, A.Yu. Demin, H.E. Scheibler, V.L. Alperovich, O.E. Tereshchenko","doi":"10.1103/physrevapplied.22.024008","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024008","url":null,"abstract":"Optical and photoemission measurements were performed on alkali antimonide <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes in order to determine their energy-band diagrams, elucidate the photoemission pathways, and explore the options for interface engineering in order to reach high quantum efficiencies of the photocathodes. This study is motivated by the recent discovery of optical orientation in <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> and emission of spin-polarized electrons from <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes [V.S. Rusetsky <i>et al.</i>, Phys. Rev. Lett. <b>129</b>, 166802 (2022)]. We have shown that the band gap <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>E</mi><mi>g</mi></msub></math> of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> at <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>T</mi><mo>=</mo><mn>295</mn></math> K lies within the range of 1.40–1.44 eV. The <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi></math> surface activation by the deposition of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Cs</mi></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Sb</mi></math> results in effective electron affinity decrease by approximately 0.37 eV, and in an increase of the quantum efficiency up to 0.2 electrons per incident photon. The analysis of longitudinal energy distribution curves (EDCs) proves that the surface of activated <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Na</mi><mn>2</mn></msub><mi>KSb</mi><mo>/</mo><msub><mi>Cs</mi><mi>x</mi></msub><mi>Sb</mi></math> photocathodes have negative effective electron affinity of approximately <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>−</mo><mn>0.1</mn></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>−</mo><mn>0.25</mn></math> eV at <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>T</mi><mo>=</mo><mn>295</mn></math> and 80 K, respectively. EDC measurements under increasing photon energy <math display","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"190 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1103/physrevapplied.22.024006
Moein Malekakhlagh, Timothy Phung, Daniel Puzzuoli, Kentaro Heya, Neereja Sundaresan, Jason Orcutt
Achieving high-fidelity direct two-qubit gates over meter-scale quantum interconnects is challenging, in part due to the multimode nature of such systems. One alternative scheme is to combine local operations with remote quantum state transfer or remote entanglement. Here, we theoretically study quantum state transfer and entanglement generation for two distant qubits, equipped with tunable interactions, over a common multimode interconnect. We model the performance of the superadiabatic transitionless driving (SATD) protocol for adiabatic passage and demonstrate various favorable improvements over the standard method. In particular, by suppressing leakage to a select (resonant) interconnect mode, SATD breaks the speed-limit relation imposed by the qubit-interconnect interaction , where instead the operation time is limited by leakage to the adjacent modes, i.e., the free spectral range of the interconnect, allowing for fast operations even with weak . Furthermore, we identify a multimode error mechanism for Bell-state generation using such adiabatic protocols, in which the even/odd modal dependence of qubit-interconnect interaction breaks down the dark-state symmetry, leading to detrimental adiabatic overlap with the odd modes growing as . Therefore, adopting a weak coupling, imposed by a multimode interconnect, SATD provides a significant improvement in terms of operation speed and consequently sensitivity to incoherent error.
在米级量子互连上实现高保真直接双量子比特门具有挑战性，部分原因在于此类系统的多模性质。一种替代方案是将本地操作与远程量子态转移或远程纠缠结合起来。在这里，我们从理论上研究了两个远距离量子比特的量子态转移和纠缠生成，这两个量子比特配备了可调的相互作用，通过一个普通的多模互连。我们模拟了绝热通过的超绝热无过渡驱动（SATD）协议的性能，并展示了与标准方法相比的各种有利改进。特别是，通过抑制向选择（共振）互连模式的泄漏，SATD 打破了由量子比特-互连相互作用 g 强加的速度限制关系，运行时间反而受限于向相邻模式的泄漏，即此外，我们还发现了利用这种绝热协议生成贝尔态的多模误差机制，其中，量子比特-互连相互作用的偶数/奇数模依赖性打破了暗态对称性，导致与奇数模的有害绝热重叠随着（g/Δc）2 的增长而增加。因此，采用多模互连施加的弱耦合，SATD 在运行速度和对非相干误差的敏感性方面都有显著改善。
{"title":"Enhanced quantum state transfer and Bell-state generation over long-range multimode interconnects via superadiabatic transitionless driving","authors":"Moein Malekakhlagh, Timothy Phung, Daniel Puzzuoli, Kentaro Heya, Neereja Sundaresan, Jason Orcutt","doi":"10.1103/physrevapplied.22.024006","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024006","url":null,"abstract":"Achieving high-fidelity direct two-qubit gates over meter-scale quantum interconnects is challenging, in part due to the multimode nature of such systems. One alternative scheme is to combine local operations with remote quantum state transfer or remote entanglement. Here, we theoretically study quantum state transfer and entanglement generation for two distant qubits, equipped with tunable interactions, over a common multimode interconnect. We model the performance of the superadiabatic transitionless driving (SATD) protocol for adiabatic passage and demonstrate various favorable improvements over the standard method. In particular, by suppressing leakage to a select (resonant) interconnect mode, SATD breaks the speed-limit relation imposed by the qubit-interconnect interaction <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>g</mi></math>, where instead the operation time is limited by leakage to the adjacent modes, i.e., the free spectral range <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"normal\">Δ</mi><mi>c</mi></msub></math> of the interconnect, allowing for fast operations even with weak <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>g</mi></math>. Furthermore, we identify a multimode error mechanism for Bell-state generation using such adiabatic protocols, in which the even/odd modal dependence of qubit-interconnect interaction breaks down the dark-state symmetry, leading to detrimental adiabatic overlap with the odd modes growing as <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo stretchy=\"false\">(</mo><mi>g</mi><mo>/</mo><msub><mi mathvariant=\"normal\">Δ</mi><mi>c</mi></msub><msup><mo stretchy=\"false\">)</mo><mn>2</mn></msup></math>. Therefore, adopting a weak coupling, imposed by a multimode interconnect, SATD provides a significant improvement in terms of operation speed and consequently sensitivity to incoherent error.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"46 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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