Pub Date : 2024-09-19DOI: 10.1103/physrevapplied.22.034046
Lidiia Ushii, Andrei Slavin, Roman Verba
Nonreciprocity of propagation of surface acoustic waves (SAWs) in the microwave frequency band can be achieved using the magnetoelastic interaction of SAWs with spin waves (SWs) propagating in magnetic heterostructures. Recent works have shown that the ultimate isolation of a counterpropagating hybridized SAW/SW is achieved in heterostructures consisting of a synthetic antiferromagnet—a ferromagnetic (FM) bilayer with antiferromagnetic Ruderman-Kittel-Kasuya-Yosida interlayer coupling—placed on top of a piezoelectric acoustic waveguide. In this work, we study in detail a more practical and technologically simpler system based on an FM bilayer, where layers are coupled by only dipole-dipole interaction, and having noncollinear magnetizations of the FM layers. A weak in-plane anisotropy with noncollinear easy axes in the layers is shown to be the only essential factor for the realization of strongly nonreciprocal propagation of a hybridized SAW/SW. We formulate requirements for the relative orientation of the layer’s magnetizations and wave propagation direction necessary to realize an efficient SAW isolator, and demonstrate examples of SAW transmission characteristics which prove the possibility of achieving an isolation exceeding 50 dB for a submillimeter-long FM bilayer with insertion losses of just a few decibels more than those of a pure SAW device. In addition to relative fabrication simplicity, the proposed magnetoelastic heterostructure exhibits a reasonable robustness in respect to deviations in the anisotropy axes and/or bias field directions—an important benefit for device mass production.
利用声表面波与在磁性异质结构中传播的自旋波（SW）之间的磁弹性相互作用，可以实现声表面波在微波频段的非互易传播。最近的研究表明，在由合成反铁磁体--具有反铁磁性 Ruderman-Kittel-Kasuya-Yosida 层间耦合的铁磁（FM）双层结构--放置在压电声波导顶部的异质结构中，可以实现反传播杂化 SAW/SW 的最终隔离。在这项工作中，我们详细研究了一个基于调频双电层的更实用、技术上更简单的系统，其中各层仅通过偶极-偶极相互作用耦合，并且调频层的磁化不共线。研究表明，各层中具有非共线易轴的微弱面内各向异性是实现混合声表面波/声表面波强非对等传播的唯一基本因素。我们提出了实现高效声表面波隔离器所需的层磁化相对方向和波传播方向的要求，并演示了声表面波传输特性的示例，证明亚毫米长的调频双层膜可以实现超过 50 dB 的隔离度，而插入损耗仅比纯声表面波器件高出几个分贝。除了相对简单的制造工艺外，所提出的磁弹性异质结构对各向异性轴和/或偏置场方向的偏差表现出合理的鲁棒性--这对器件的大规模生产具有重要的好处。
{"title":"Nonreciprocity of surface acoustic waves coupled to spin waves in a ferromagnetic bilayer with noncollinear layer magnetizations","authors":"Lidiia Ushii, Andrei Slavin, Roman Verba","doi":"10.1103/physrevapplied.22.034046","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034046","url":null,"abstract":"Nonreciprocity of propagation of surface acoustic waves (SAWs) in the microwave frequency band can be achieved using the magnetoelastic interaction of SAWs with spin waves (SWs) propagating in magnetic heterostructures. Recent works have shown that the ultimate isolation of a counterpropagating hybridized SAW/SW is achieved in heterostructures consisting of a synthetic antiferromagnet—a ferromagnetic (FM) bilayer with antiferromagnetic Ruderman-Kittel-Kasuya-Yosida interlayer coupling—placed on top of a piezoelectric acoustic waveguide. In this work, we study in detail a more practical and technologically simpler system based on an FM bilayer, where layers are coupled by only dipole-dipole interaction, and having noncollinear magnetizations of the FM layers. A weak in-plane anisotropy with noncollinear easy axes in the layers is shown to be the only essential factor for the realization of strongly nonreciprocal propagation of a hybridized SAW/SW. We formulate requirements for the relative orientation of the layer’s magnetizations and wave propagation direction necessary to realize an efficient SAW isolator, and demonstrate examples of SAW transmission characteristics which prove the possibility of achieving an isolation exceeding 50 dB for a submillimeter-long FM bilayer with insertion losses of just a few decibels more than those of a pure SAW device. In addition to relative fabrication simplicity, the proposed magnetoelastic heterostructure exhibits a reasonable robustness in respect to deviations in the anisotropy axes and/or bias field directions—an important benefit for device mass production.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248047","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}
Satellite-based quantum communication is a promising approach for establishing global-scale quantum networks. In free-space quantum channels, single-mode-fiber coupling plays a crucial role in increasing the signal-to-noise ratio of daylight quantum key distribution (QKD) and ensuring compatibility with standard fiber-based QKD protocols. However, consistently achieving high efficiency and stable single-mode-fiber coupling under strong atmospheric turbulence remains an ongoing experimental challenge. In this study, we experimentally demonstrate an adaptive method based on convolutional neural networks capable of directly estimating phase information from a single defocused image. We developed a convolutional neural network to establish the relationship between intensity distribution and phase information of turbulent distortions. We demonstrate the real-time performance of our deep-learning adaptive method in increasing single-mode-fiber coupling efficiency across various turbulence scales and quantify turbulence frequencies. Notably, the method proved highly effective in strong-turbulence scenarios, with frequencies reaching up to 200 Hz, leading to a significant increase in single-mode-fiber coupling efficiency. We demonstrate the corrective capability of our adaptive method for strong turbulence, enabled by the generalization of the convolutional neural network. Our results offer an efficient solution for daytime free-space QKD applications.
{"title":"Experimental demonstration of deep-learning-enabled adaptive optics","authors":"Hao-Bin Fu, Zu-Yang Wan, Yu-huai Li, Bo Li, Zhen Rong, Gao-Qiang Wang, Juan Yin, Ji-Gang Ren, Wei-Yue Liu, Sheng-Kai Liao, Yuan Cao, Cheng-Zhi Peng","doi":"10.1103/physrevapplied.22.034047","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034047","url":null,"abstract":"Satellite-based quantum communication is a promising approach for establishing global-scale quantum networks. In free-space quantum channels, single-mode-fiber coupling plays a crucial role in increasing the signal-to-noise ratio of daylight quantum key distribution (QKD) and ensuring compatibility with standard fiber-based QKD protocols. However, consistently achieving high efficiency and stable single-mode-fiber coupling under strong atmospheric turbulence remains an ongoing experimental challenge. In this study, we experimentally demonstrate an adaptive method based on convolutional neural networks capable of directly estimating phase information from a single defocused image. We developed a convolutional neural network to establish the relationship between intensity distribution and phase information of turbulent distortions. We demonstrate the real-time performance of our deep-learning adaptive method in increasing single-mode-fiber coupling efficiency across various turbulence scales and quantify turbulence frequencies. Notably, the method proved highly effective in strong-turbulence scenarios, with frequencies reaching up to 200 Hz, leading to a significant increase in single-mode-fiber coupling efficiency. We demonstrate the corrective capability of our adaptive method for strong turbulence, enabled by the generalization of the convolutional neural network. Our results offer an efficient solution for daytime free-space QKD applications.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248061","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}
We propose and demonstrate a static quantum dot on a potential hilltop to generate and analyze ballistic hot electrons along a quantum Hall edge channel well above the chemical potential. High-energy resolution associated with discrete energy levels is attractive for studying hot-electron dynamics. In particular, the energy distribution function of hot electrons weakly coupled to cold electrons is investigated to reveal spectral diffusion with energy relaxation. The analysis allows us to estimate the maximum energy exchange per scattering, which is a key parameter to describe interacting electrons in the edge channel.
{"title":"Static quantum dot on a large potential hilltop for generating and analyzing hot electrons in the quantum Hall regime","authors":"Ryo Oishi, Yuto Hongu, Tokuro Hata, Chaojing Lin, Takafumi Akiho, Koji Muraki, Toshimasa Fujisawa","doi":"10.1103/physrevapplied.22.034043","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034043","url":null,"abstract":"We propose and demonstrate a static quantum dot on a potential hilltop to generate and analyze ballistic hot electrons along a quantum Hall edge channel well above the chemical potential. High-energy resolution associated with discrete energy levels is attractive for studying hot-electron dynamics. In particular, the energy distribution function of hot electrons weakly coupled to cold electrons is investigated to reveal spectral diffusion with energy relaxation. The analysis allows us to estimate the maximum energy exchange per scattering, which is a key parameter to describe interacting electrons in the edge channel.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248048","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}
Using modulation transfer spectroscopy, we achieve the frequency stabilization of a high-power 3-W blue laser at the wavelength of 420 nm to the <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Rb</mi></math> <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>5</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math>–<math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>6</mn><msub><mi>P</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math> transition. The in-loop frequency stability of this laser is <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>1.8</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>11</mn></mrow></msup><mo>/</mo><msqrt><mi>τ</mi></msqrt></math>, reaching <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>1.7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>12</mn></mrow></msup></math> at 100 s and <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>13</mn></mrow></msup></math> at 1000 s. An external power feedback loop is established using an acousto-optic modulator, employing the zeroth-order diffracted light for power stabilization, achieving an in-loop power stability of <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>1.0</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> at 1 s. Moreover, the continuous mode-hop free interval of this high-power laser can simultaneously cover the <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>5</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math>–<math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mn>6</mn><msub><mi>P</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math> transitions of <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi></mi><mn>85</mn></msup><mtext>Rb</mtext></math> and <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi></mi><mn>87</mn></msup><mtext>Rb</mtext></math>, with successful locking achieved for both isotopes, providing a comprehensive analysis of the <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Rb</mi></math> atomic transitions in the blue spectral region. As an application, this 3-W 420-nm laser with excellent power and frequency stabilities is used as a repumping source for diffuse laser cooling of <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi></mi><mn>87</mn></msup><mtext>Rb</mtext></math> atoms, realizing a one-meter-long cold-atom cloud. This paves the way for using blue-light cooling to realize a cold-<math disp
{"title":"Power-stabilized 3-W blue laser locked to the 420-nm transition in rubidium","authors":"Jia Zhang, Xiaolei Guan, Xun Gao, Zhiyang Wang, Xiaomin Qin, Zijie Liu, Hangbo Shi, Jianxiang Miao, Tiantian Shi, Jingbiao Chen","doi":"10.1103/physrevapplied.22.034045","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034045","url":null,"abstract":"Using modulation transfer spectroscopy, we achieve the frequency stabilization of a high-power 3-W blue laser at the wavelength of 420 nm to the <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Rb</mi></math> <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>5</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math>–<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>6</mn><msub><mi>P</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math> transition. The in-loop frequency stability of this laser is <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>1.8</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>11</mn></mrow></msup><mo>/</mo><msqrt><mi>τ</mi></msqrt></math>, reaching <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>1.7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>12</mn></mrow></msup></math> at 100 s and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>13</mn></mrow></msup></math> at 1000 s. An external power feedback loop is established using an acousto-optic modulator, employing the zeroth-order diffracted light for power stabilization, achieving an in-loop power stability of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>1.0</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> at 1 s. Moreover, the continuous mode-hop free interval of this high-power laser can simultaneously cover the <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>5</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math>–<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>6</mn><msub><mi>P</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math> transitions of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi></mi><mn>85</mn></msup><mtext>Rb</mtext></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi></mi><mn>87</mn></msup><mtext>Rb</mtext></math>, with successful locking achieved for both isotopes, providing a comprehensive analysis of the <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Rb</mi></math> atomic transitions in the blue spectral region. As an application, this 3-W 420-nm laser with excellent power and frequency stabilities is used as a repumping source for diffuse laser cooling of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi></mi><mn>87</mn></msup><mtext>Rb</mtext></math> atoms, realizing a one-meter-long cold-atom cloud. This paves the way for using blue-light cooling to realize a cold-<math disp","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248012","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 : 2024-09-18DOI: 10.1103/physrevapplied.22.034044
M.A. Wolfe, Brighton X. Coe, Justin S. Edwards, Tyler J. Kovach, Thomas McJunkin, Benjamin Harpt, D.E. Savage, M.G. Lagally, R. McDermott, Mark Friesen, Shimon Kolkowitz, M.A. Eriksson
Optical illumination of quantum dot qubit devices at cryogenic temperatures, while not well studied, is often used to recover operating conditions after undesired shocking events or charge injection. Here, we demonstrate systematic threshold-voltage shifts in a dopant-free / field-effect transistor using a near-infrared (780-nm) laser diode. We find that illumination under an applied gate voltage can be used to set a specific, stable, and reproducible threshold voltage that, over a wide range in gate bias, is equal to that gate bias. Outside this range, the threshold voltage can still be tuned, although the resulting threshold voltage is no longer equal to the applied gate bias during illumination. We present a simple and intuitive model that provides a mechanism for the tunability in the gate bias. The model presented also explains why cryogenic illumination is successful at resetting quantum dot qubit devices after undesired charging events.
{"title":"Control of threshold voltages in Si/Si0.7Ge0.3 quantum devices via optical illumination","authors":"M.A. Wolfe, Brighton X. Coe, Justin S. Edwards, Tyler J. Kovach, Thomas McJunkin, Benjamin Harpt, D.E. Savage, M.G. Lagally, R. McDermott, Mark Friesen, Shimon Kolkowitz, M.A. Eriksson","doi":"10.1103/physrevapplied.22.034044","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034044","url":null,"abstract":"Optical illumination of quantum dot qubit devices at cryogenic temperatures, while not well studied, is often used to recover operating conditions after undesired shocking events or charge injection. Here, we demonstrate systematic threshold-voltage shifts in a dopant-free <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Si</mi></math>/<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Si</mi></math><math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi></mi><mrow><mn>0.7</mn></mrow></msub></math><math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Ge</mi></math><math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi></mi><mrow><mn>0.3</mn></mrow></msub></math> field-effect transistor using a near-infrared (780-nm) laser diode. We find that illumination under an applied gate voltage can be used to set a specific, stable, and reproducible threshold voltage that, over a wide range in gate bias, is equal to that gate bias. Outside this range, the threshold voltage can still be tuned, although the resulting threshold voltage is no longer equal to the applied gate bias during illumination. We present a simple and intuitive model that provides a mechanism for the tunability in the gate bias. The model presented also explains why cryogenic illumination is successful at resetting quantum dot qubit devices after undesired charging events.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248013","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 : 2024-09-17DOI: 10.1103/physrevapplied.22.034041
Pierre Azam, Robin Kaiser
Machine learning is becoming a widely used technique with impressive growth due to the diversity of problems of societal interest for which it can offer practical solutions. This increase of applications and required resources start to become limited by present-day hardware technologies. Indeed, novel machine learning subjects such as large language models or high-resolution image recognition raise the question of large computing time and energy cost of the required computation. In this context, optical platforms have been designed for several years with the goal of developing more efficient hardware for machine learning. Among different explored platforms, optical free-space propagation offers various advantages: parallelism, low energy cost, and computational speed. Here, we present a new design combining the strong and tunable nonlinear properties of a light beam propagating through a hot atomic vapor with an extreme learning machine model. We numerically and experimentally demonstrate the enhancement of the training using such free-space nonlinear propagation on an MNIST image classification task. We point out different experimental hyperparameters that can be further optimized to improve the accuracy of the platform.
{"title":"Optically accelerated extreme learning machine using hot atomic vapors","authors":"Pierre Azam, Robin Kaiser","doi":"10.1103/physrevapplied.22.034041","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034041","url":null,"abstract":"Machine learning is becoming a widely used technique with impressive growth due to the diversity of problems of societal interest for which it can offer practical solutions. This increase of applications and required resources start to become limited by present-day hardware technologies. Indeed, novel machine learning subjects such as large language models or high-resolution image recognition raise the question of large computing time and energy cost of the required computation. In this context, optical platforms have been designed for several years with the goal of developing more efficient hardware for machine learning. Among different explored platforms, optical free-space propagation offers various advantages: parallelism, low energy cost, and computational speed. Here, we present a new design combining the strong and tunable nonlinear properties of a light beam propagating through a hot atomic vapor with an extreme learning machine model. We numerically and experimentally demonstrate the enhancement of the training using such free-space nonlinear propagation on an MNIST image classification task. We point out different experimental hyperparameters that can be further optimized to improve the accuracy of the platform.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248014","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 : 2024-09-17DOI: 10.1103/physrevapplied.22.034042
Chengyuan Cai, Zubiao Zhang, Ji Zou, Gerrit E. W. Bauer, Tao Yu
We address the photonic spin-orbit coupling known from nano-optics and plasmonics in the microwave regime. The spin and momentum of microwaves emitted by an excited magnetic particle are locked by with a fixed chirality when evanescent along . This field excites magnons in a nearby magnetic film in the form of directional beams that rotate with the magnetization direction. The exchange of these magnons between two distant nanomagnets leads to a highly tunable strong coupling and entangles their excited states.
我们探讨了微波体系中纳米光学和等离子体学中已知的光子自旋轨道耦合。受激磁性粒子发射的微波的自旋 S 和动量 q 被 q⋅S=0 锁定，当沿 n^⊥q 蒸发时，具有固定的手性 n^⋅（S^×q^）=1。这个磁场会在附近的磁性薄膜中激发出磁子，这些磁子以定向束的形式随磁化方向旋转。这些磁子在两个相距甚远的纳米磁体之间的交换导致了高度可调的强耦合，并使它们的激发态纠缠在一起。
{"title":"Spin-orbit-locked coupling of localized microwaves to magnons","authors":"Chengyuan Cai, Zubiao Zhang, Ji Zou, Gerrit E. W. Bauer, Tao Yu","doi":"10.1103/physrevapplied.22.034042","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034042","url":null,"abstract":"We address the photonic spin-orbit coupling known from nano-optics and plasmonics in the microwave regime. The spin <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">S</mi></mrow></math> and momentum <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">q</mi></mrow></math> of microwaves emitted by an excited magnetic particle are locked by <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">q</mi></mrow><mo>⋅</mo><mrow><mi mathvariant=\"bold\">S</mi></mrow><mo>=</mo><mn>0</mn></math> with a fixed chirality <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mover><mrow><mi mathvariant=\"bold\">n</mi></mrow><mo stretchy=\"false\">^</mo></mover></mrow><mo>⋅</mo><mo stretchy=\"false\">(</mo><mrow><mover><mi mathvariant=\"bold\">S</mi><mo stretchy=\"false\">^</mo></mover></mrow><mo>×</mo><mrow><mover><mi mathvariant=\"bold\">q</mi><mo stretchy=\"false\">^</mo></mover></mrow><mo stretchy=\"false\">)</mo><mo>=</mo><mn>1</mn></math> when evanescent along <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mover><mrow><mi mathvariant=\"bold\">n</mi></mrow><mo stretchy=\"false\">^</mo></mover></mrow><mo>⊥</mo><mrow><mi mathvariant=\"bold\">q</mi></mrow></math>. This field excites magnons in a nearby magnetic film in the form of directional beams that rotate with the magnetization direction. The exchange of these magnons between two distant nanomagnets leads to a highly tunable strong coupling and entangles their excited states.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248052","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 : 2024-09-16DOI: 10.1103/physrevapplied.22.034038
Lautaro Labarca, Othmane Benhayoune-Khadraoui, Alexandre Blais, Adrian Parra-Rodriguez
We provide a systematic method for constructing effective dispersive Lindblad master equations to describe weakly anharmonic superconducting circuits coupled by a generic dissipationless nonreciprocal linear system, with effective coupling parameters and decay rates written in terms of the immittance parameters characterizing the coupler. This article extends the foundational work of Solgun et al. [IEEE Trans. Microw. Theory Techn. 67, 928 (2019)] for linear reciprocal couplers described by an impedance response. Notably, we expand the existing toolbox to incorporate nonreciprocal elements, account for direct stray coupling between immittance ports, circumvent potential singularities, and include collective dissipative effects that arise from interactions with external common environments. We illustrate the use of our results with a circuit of weakly anharmonic Josephson junctions coupled to a multiport nonreciprocal environment and a dissipative port. The results obtained here can be used for the design of complex superconducting quantum processors with nontrivial routing of quantum information, as well as analog quantum simulators of condensed matter systems.
我们提供了一种构建有效色散林德布拉德主方程的系统方法，以描述由通用无耗散非互易线性系统耦合的弱非谐波超导电路，其有效耦合参数和衰减率用表征耦合器的惰性参数来表示。本文扩展了 Solgun 等人 [IEEE Trans. Microw. Theory Techn.值得注意的是，我们扩展了现有的工具箱，纳入了非互易元素，考虑了互易端口之间的直接杂散耦合，规避了潜在的奇异性，并包含了与外部共同环境相互作用产生的集体耗散效应。我们用一个与多端口非互易环境和耗散端口耦合的弱非谐波约瑟夫森结电路来说明我们的结果的用途。这里获得的结果可用于设计复杂的超导量子处理器与量子信息的非线性路由，以及凝聚态系统的模拟量子模拟器。
{"title":"Toolbox for nonreciprocal dispersive models in circuit quantum electrodynamics","authors":"Lautaro Labarca, Othmane Benhayoune-Khadraoui, Alexandre Blais, Adrian Parra-Rodriguez","doi":"10.1103/physrevapplied.22.034038","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034038","url":null,"abstract":"We provide a systematic method for constructing effective dispersive Lindblad master equations to describe weakly anharmonic superconducting circuits coupled by a generic dissipationless nonreciprocal linear system, with effective coupling parameters and decay rates written in terms of the immittance parameters characterizing the coupler. This article extends the foundational work of Solgun <i>et al.</i> [IEEE Trans. Microw. Theory Techn. 67, 928 (2019)] for linear reciprocal couplers described by an impedance response. Notably, we expand the existing toolbox to incorporate nonreciprocal elements, account for direct stray coupling between immittance ports, circumvent potential singularities, and include collective dissipative effects that arise from interactions with external common environments. We illustrate the use of our results with a circuit of weakly anharmonic Josephson junctions coupled to a multiport nonreciprocal environment and a dissipative port. The results obtained here can be used for the design of complex superconducting quantum processors with nontrivial routing of quantum information, as well as analog quantum simulators of condensed matter systems.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248054","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 : 2024-09-16DOI: 10.1103/physrevapplied.22.034040
G.Y. Thiancourt, S.M. Ngom, N. Bardou, T. Devolder
The dispersion relation of spin waves can vary monotonically about the center of the Brillouin zone, allowing zero-momentum wavepackets to flow unidirectionally, which is of interest for applications. Techniques such as propagating-spin-wave spectroscopy are inoperative in such cases because of the difficulty to identify the spin-wave wavevector at a particular frequency within a spectrum. Here we present a method to analyze this case and apply it to acoustic spin waves in a synthetic antiferromagnet in the scissors state, in which we confirm that propagation parallel to the applied fields is unidirectional. Interestingly, we find that in this unidirectional situation, the phase accumulated by the spin waves propagating between two antennas is not proportional to the antenna spacing. It is also a function of the two other lengths of the problem: the antenna width and the spin-wave decay length. Accounting for them is required to avoid wavevector errors in the dispersion relations.
{"title":"Unidirectional spin waves measured using propagating-spin-wave spectroscopy","authors":"G.Y. Thiancourt, S.M. Ngom, N. Bardou, T. Devolder","doi":"10.1103/physrevapplied.22.034040","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034040","url":null,"abstract":"The dispersion relation of spin waves can vary monotonically about the center of the Brillouin zone, allowing zero-momentum wavepackets to flow unidirectionally, which is of interest for applications. Techniques such as propagating-spin-wave spectroscopy are inoperative in such cases because of the difficulty to identify the spin-wave wavevector at a particular frequency within a spectrum. Here we present a method to analyze this case and apply it to acoustic spin waves in a synthetic antiferromagnet in the scissors state, in which we confirm that propagation parallel to the applied fields is unidirectional. Interestingly, we find that in this unidirectional situation, the phase accumulated by the spin waves propagating between two antennas is not proportional to the antenna spacing. It is also a function of the two other lengths of the problem: the antenna width and the spin-wave decay length. Accounting for them is required to avoid wavevector errors in the dispersion relations.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248049","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 : 2024-09-16DOI: 10.1103/physrevapplied.22.034039
Michal Mrnka, Thomas Whittaker, David B. Phillips, Euan Hendry, Will Whittow
The miniaturization of optical systems is an ongoing challenge across the electromagnetic spectrum. While the thickness of optical elements themselves can be reduced using advances in metamaterials, it is the voids between these elements—which are necessary parts of an optical system—that occupy most of the volume. Recently, a novel optical element coined a “spaceplate” has been proposed, which replaces a region of free space with a thinner optical element that emulates the free-space optical response function—thus having the potential to substantially shrink the volume of optical systems. While there have been a few proof-of-principle demonstrations of spaceplates, they have not yet been deployed in a real-world optical system. In this work, we use a bespoke-designed spaceplate to reduce the length of a gradient-index- (GRIN) lens microwave antenna. Our antenna is designed to operate at 23.5 GHz and the incorporation of a nonlocal metamaterial spaceplate enables the distance between the antenna feed and the GRIN lens to be reduced by almost a factor of 2. We find that the radiation patterns from a conventional and space-squeezed antenna are very similar, with a very low cross-polarization, and only a minor increase in the side-lobe levels when introducing the spaceplate. Our work represents a demonstration of a spaceplate integrated into a real-world optical system operating in microwave spectral region, highlighting the potential for this concept to reduce the physical size of systems in applications including imaging, spectroscopy, radar, and communications.
{"title":"Shrinking a gradient-index-lens antenna system with a spaceplate","authors":"Michal Mrnka, Thomas Whittaker, David B. Phillips, Euan Hendry, Will Whittow","doi":"10.1103/physrevapplied.22.034039","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034039","url":null,"abstract":"The miniaturization of optical systems is an ongoing challenge across the electromagnetic spectrum. While the thickness of optical elements themselves can be reduced using advances in metamaterials, it is the voids between these elements—which are necessary parts of an optical system—that occupy most of the volume. Recently, a novel optical element coined a “spaceplate” has been proposed, which replaces a region of free space with a thinner optical element that emulates the free-space optical response function—thus having the potential to substantially shrink the volume of optical systems. While there have been a few proof-of-principle demonstrations of spaceplates, they have not yet been deployed in a real-world optical system. In this work, we use a bespoke-designed spaceplate to reduce the length of a gradient-index- (GRIN) lens microwave antenna. Our antenna is designed to operate at 23.5 GHz and the incorporation of a nonlocal metamaterial spaceplate enables the distance between the antenna feed and the GRIN lens to be reduced by almost a factor of 2. We find that the radiation patterns from a conventional and space-squeezed antenna are very similar, with a very low cross-polarization, and only a minor increase in the side-lobe levels when introducing the spaceplate. Our work represents a demonstration of a spaceplate integrated into a real-world optical system operating in microwave spectral region, highlighting the potential for this concept to reduce the physical size of systems in applications including imaging, spectroscopy, radar, and communications.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248050","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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