Functional imaging equipment based on miniaturized atomic magnetometers with array arrangement exhibits promising prospects in biomagnetic scenarios. However, crosstalk from the modulated magnetic field between adjacent sensors degrades the imaging accuracy. To address this issue, this study proposes an all-optical dual-axis zero-field atomic magnetometer using light-shift modulation. We utilize an acousto-optic modulator to modulate a detuned circularly polarized beam for pumping the atomic spin ensembles. This beam allows for the optical modulation of spin polarization and meanwhile generates a light-shift modulation, effectively replacing the conventional magnetic field modulation. By using a probe beam to detect the optical rotation angle perpendicular to the direction of the pump beam, we construct an all-optical configuration of a longitudinally modulated atomic magnetometer, enabling dual-axis magnetic field measurements. Experimental results demonstrate dual-axis sensitivities of 29 and , respectively. This method eliminates the need for conventional coil-based magnetic field modulation, thereby paving the way for potential applications in magnetocardiography and magnetoencephalography.
{"title":"All-optical dual-axis zero-field atomic magnetometer using light-shift modulation","authors":"Xiaoyu Li, Bangcheng Han, Kaixuan Zhang, Ziao Liu, Shuying Wang, Yifan Yan, Jixi Lu","doi":"10.1103/physrevapplied.21.014023","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014023","url":null,"abstract":"Functional imaging equipment based on miniaturized atomic magnetometers with array arrangement exhibits promising prospects in biomagnetic scenarios. However, crosstalk from the modulated magnetic field between adjacent sensors degrades the imaging accuracy. To address this issue, this study proposes an all-optical dual-axis zero-field atomic magnetometer using light-shift modulation. We utilize an acousto-optic modulator to modulate a detuned circularly polarized beam for pumping the atomic spin ensembles. This beam allows for the optical modulation of spin polarization and meanwhile generates a light-shift modulation, effectively replacing the conventional magnetic field modulation. By using a probe beam to detect the optical rotation angle perpendicular to the direction of the pump beam, we construct an all-optical configuration of a longitudinally modulated atomic magnetometer, enabling dual-axis magnetic field measurements. Experimental results demonstrate dual-axis sensitivities of 29 and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>15</mn><mspace width=\"0.2em\"></mspace><mi>fT</mi><mo>/</mo><msup><mi>Hz</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math>, respectively. This method eliminates the need for conventional coil-based magnetic field modulation, thereby paving the way for potential applications in magnetocardiography and magnetoencephalography.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"23 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139475823","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 : 2024-01-12DOI: 10.1103/physrevapplied.21.014021
G. Liu, A. Lingenfelter, V.R. Joshi, N.E. Frattini, V.V. Sivak, S. Shankar, M.H. Devoret
We present a way to achieve fully directional, quantum-limited phase-preserving amplification in a four-port, four-mode superconducting Josephson circuit by utilizing interference between six parametric processes that couple all four modes. Full directionality, defined as the reverse isolation surpassing forward gain between the matched input and output ports of the amplifier, ensures its robustness against impedance mismatch that might be present at its output port during applications. Unlike existing directional phase-preserving amplifiers, both the minimal backaction and the quantum-limited added noise of this amplifier remains unaffected by noise incident on its output port. In addition, the matched input and output ports allow direct on-chip integration of these amplifiers with other circuit QED components, facilitating scaling up of superconducting quantum processors.
我们提出了一种在四端口、四模式超导约瑟夫森电路中实现全定向、量子限相保留放大的方法，即利用耦合所有四种模式的六个参量过程之间的干扰。全方向性是指放大器匹配的输入和输出端口之间的反向隔离度超过正向增益，这确保了放大器在应用过程中能够抵御输出端口可能存在的阻抗失配。与现有的定向保相放大器不同，该放大器的最小反向作用和量子限制附加噪声均不受输出端口噪声的影响。此外，匹配的输入和输出端口允许这些放大器与其他电路 QED 组件直接进行片上集成，从而促进了超导量子处理器的扩展。
{"title":"Fully directional quantum-limited phase-preserving amplifier","authors":"G. Liu, A. Lingenfelter, V.R. Joshi, N.E. Frattini, V.V. Sivak, S. Shankar, M.H. Devoret","doi":"10.1103/physrevapplied.21.014021","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014021","url":null,"abstract":"We present a way to achieve fully directional, quantum-limited phase-preserving amplification in a four-port, four-mode superconducting Josephson circuit by utilizing interference between six parametric processes that couple all four modes. Full directionality, defined as the reverse isolation surpassing forward gain between the matched input and output ports of the amplifier, ensures its robustness against impedance mismatch that might be present at its output port during applications. Unlike existing directional phase-preserving amplifiers, both the minimal backaction and the quantum-limited added noise of this amplifier remains unaffected by noise incident on its output port. In addition, the matched input and output ports allow direct on-chip integration of these amplifiers with other circuit QED components, facilitating scaling up of superconducting quantum processors.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"30 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464375","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 : 2024-01-12DOI: 10.1103/physrevapplied.21.014020
Kexin Zeng, Yawen Luo, Like Zhang, Huayao Tu, Yanxiang Luo, Xuan Zhang, Bin Fang, Zhongming Zeng
Magnetic-tunnel-junction- (MTJ) based spintronic devices have demonstrated significant potential in neuromorphic computing. Here, we report an artificial synapse, which can be modulated by rf signals directly based on the nanoscale MTJs with perpendicular magnetic anisotropy (PMA). To utilize multiple rf signals in parallel, we take an approach to change the resonance frequencies of MTJs by changing the PMA between the free layer and barrier, which can expand the application range of rf signal processing. Moreover, we experimentally demonstrate that MTJs with PMA can serve as an rf synapse with adjustable positive and negative weights. We have achieved effective classification of rf signals with an accuracy exceeding 96% through experimental results as synaptic weights, comparable to that of equivalent software-based neural networks. This work may pave the way for the development of rf-oriented hardware artificial neural networks.
{"title":"Radio-frequency-modulated artificial synapses based on magnetic tunnel junctions with perpendicular magnetic anisotropy","authors":"Kexin Zeng, Yawen Luo, Like Zhang, Huayao Tu, Yanxiang Luo, Xuan Zhang, Bin Fang, Zhongming Zeng","doi":"10.1103/physrevapplied.21.014020","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014020","url":null,"abstract":"Magnetic-tunnel-junction- (MTJ) based spintronic devices have demonstrated significant potential in neuromorphic computing. Here, we report an artificial synapse, which can be modulated by rf signals directly based on the nanoscale MTJs with perpendicular magnetic anisotropy (PMA). To utilize multiple rf signals in parallel, we take an approach to change the resonance frequencies of MTJs by changing the PMA between the <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Co</mi><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><mi>Fe</mi><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><mrow><mrow><mi mathvariant=\"normal\">B</mi></mrow></mrow></math> free layer and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Mg</mi><mi mathvariant=\"normal\">O</mi></math> barrier, which can expand the application range of rf signal processing. Moreover, we experimentally demonstrate that MTJs with PMA can serve as an rf synapse with adjustable positive and negative weights. We have achieved effective classification of rf signals with an accuracy exceeding 96% through experimental results as synaptic weights, comparable to that of equivalent software-based neural networks. This work may pave the way for the development of rf-oriented hardware artificial neural networks.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"256 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464234","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 : 2024-01-12DOI: 10.1103/physrevapplied.21.014022
Mingrui Xu, Chunzhen Li, Yuntao Xu, Hong X. Tang
Microwave-to-optical transducers are integral to the future of superconducting quantum computing, as they would enable scaling and long-distance communication of superconducting quantum processors through optical-fiber links. However, optically induced microwave noise poses a significant challenge in achieving quantum transduction between microwave and optical frequencies. In this work, we study light-induced microwave noise in an integrated electro-optical transducer harnessing the Pockels effect of thin-film lithium niobate. We reveal three sources of added noise with distinctive time constants ranging from sub- to milliseconds. Our results provide insights into the mechanisms and corresponding mitigation strategies for light-induced microwave noise in superconducting microwave-optical transducers and pave the way toward realizing the ultimate goal of quantum transduction.
{"title":"Light-induced microwave noise in superconducting microwave-optical transducers","authors":"Mingrui Xu, Chunzhen Li, Yuntao Xu, Hong X. Tang","doi":"10.1103/physrevapplied.21.014022","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014022","url":null,"abstract":"Microwave-to-optical transducers are integral to the future of superconducting quantum computing, as they would enable scaling and long-distance communication of superconducting quantum processors through optical-fiber links. However, optically induced microwave noise poses a significant challenge in achieving quantum transduction between microwave and optical frequencies. In this work, we study light-induced microwave noise in an integrated electro-optical transducer harnessing the Pockels effect of thin-film lithium niobate. We reveal three sources of added noise with distinctive time constants ranging from sub-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>100</mn><mspace width=\"0.2em\"></mspace><mi>ns</mi></math> to milliseconds. Our results provide insights into the mechanisms and corresponding mitigation strategies for light-induced microwave noise in superconducting microwave-optical transducers and pave the way toward realizing the ultimate goal of quantum transduction.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"20 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464269","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 : 2024-01-11DOI: 10.1103/physrevapplied.21.014018
Víctor Zapatero, Marcos Curty
The passive approach to quantum key distribution (QKD) eliminates all optical modulators and random number generators from QKD systems reaching an enhanced simplicity, immunity to modulator side channels, and potentially higher repetition rates. In this work, we provide finite-key security bounds for a fully passive decoy-state Bennett-Brassard 1984 (BB84) protocol, considering a recently presented passive QKD source. With our analysis, the attainable secret-key rate is comparable to that of the perfect parameter-estimation limit, in fact differing from the key rate of the active approach by less than one order of magnitude. This demonstrates the practicality of fully passive QKD solutions.
{"title":"Finite-key security of passive quantum key distribution","authors":"Víctor Zapatero, Marcos Curty","doi":"10.1103/physrevapplied.21.014018","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014018","url":null,"abstract":"The passive approach to quantum key distribution (QKD) eliminates all optical modulators and random number generators from QKD systems reaching an enhanced simplicity, immunity to modulator side channels, and potentially higher repetition rates. In this work, we provide finite-key security bounds for a fully passive decoy-state Bennett-Brassard 1984 (BB84) protocol, considering a recently presented passive QKD source. With our analysis, the attainable secret-key rate is comparable to that of the perfect parameter-estimation limit, in fact differing from the key rate of the active approach by less than one order of magnitude. This demonstrates the practicality of fully passive QKD solutions.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"5 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464268","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 : 2024-01-11DOI: 10.1103/physrevapplied.21.014019
X. Zhang, Z. Zhu, N.P. Ong, J.R. Petta
Spin-photon coupling presents an enticing opportunity for the long-range coupling of spin qubits. The spin-photon coupling rate, , is proportional to the charge-photon coupling rate, . To move deeper into the strong-coupling regime, can be enhanced by fabricating high-impedance cavities using high-kinetic-inductance films. Here, we report dc transport and microwave response investigations of niobium nitride () films of different thicknesses. The kinetic inductance increases rapidly as the film thickness is reduced below 50 nm and for 15-nm films we measure a sheet kinetic inductance . As an application of the high-kinetic-inductance films, we fabricate compact filters that are commonly used to reduce microwave leakage in circuit quantum electrodynamics (cQED) devices. These filters feature up to 60 dB of attenuation near typical cavity resonance frequencies of GHz.
{"title":"High-impedance superconducting resonators and on-chip filters for circuit quantum electrodynamics with semiconductor quantum dots","authors":"X. Zhang, Z. Zhu, N.P. Ong, J.R. Petta","doi":"10.1103/physrevapplied.21.014019","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014019","url":null,"abstract":"Spin-photon coupling presents an enticing opportunity for the long-range coupling of spin qubits. The spin-photon coupling rate, <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>g</mi><mi>s</mi></msub></math>, is proportional to the charge-photon coupling rate, <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>g</mi><mi>c</mi></msub></math>. To move deeper into the strong-coupling regime, <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>g</mi><mi>c</mi></msub></math> can be enhanced by fabricating high-impedance cavities using high-kinetic-inductance films. Here, we report dc transport and microwave response investigations of niobium nitride (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Nb</mi><mi mathvariant=\"normal\">N</mi></math>) films of different thicknesses. The kinetic inductance increases rapidly as the film thickness is reduced below 50 nm and for 15-nm <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Nb</mi><mi mathvariant=\"normal\">N</mi></math> films we measure a sheet kinetic inductance <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>L</mi><mrow><mi>k</mi><mo>,</mo><mi>S</mi></mrow></msub><mo>=</mo><mn>41.2</mn><mspace width=\"0.2em\"></mspace><mtext>pH</mtext><mo>/</mo><mi>◻</mi></math>. As an application of the high-kinetic-inductance films, we fabricate compact <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>L</mi><mi>C</mi></math> filters that are commonly used to reduce microwave leakage in circuit quantum electrodynamics (cQED) devices. These filters feature up to 60 dB of attenuation near typical cavity resonance frequencies of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>f</mi><mi>c</mi></msub><mo>=</mo><mn>8</mn></math> GHz.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"84 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139420641","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 : 2024-01-11DOI: 10.1103/physrevapplied.21.014017
Amir Jafargholi, Romain Fleury, Mohammad Hossein Mazaheri, Jalaledin Tayebpour
This paper presents a solution to overcome the inherently limited bandwidth of substrate-integrated waveguide (SIW) slot antennas. It is analytically shown that by decreasing the permittivity of a dielectric loaded slot antenna, the resulting bandwidth increases significantly, where the widest bandwidth can be achieved when the permittivity of the dielectric is less than unity. To demonstrate this concept, a rectangular SIW slot is loaded by an array of thin wires to realize the desired low-index metamaterials (MTMs), which consequently results in a single-layer, compact, and cost-effective structure. We have measured an impedance bandwidth of 36.2%, covering the millimeter-wave (mmWave) frequency range of 19.7–28.4 GHz. The radiation efficiency is above 90%, providing at least 7.5 decibels relative to isotropic (dBi) gain through the entire frequency band, making it a potential candidate for industrial, scientific and medical (ISM) and/or automotive radar ( GHz) and 5G ( GHz). Measurements show that the proposed antenna not only has a broad impedance bandwidth but also an improved radiation bandwidth.
{"title":"Enabling Wide Bandwidth in Substrate-Integrated Waveguide Slot Antennas by Using Low-Index Metamaterials","authors":"Amir Jafargholi, Romain Fleury, Mohammad Hossein Mazaheri, Jalaledin Tayebpour","doi":"10.1103/physrevapplied.21.014017","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014017","url":null,"abstract":"This paper presents a solution to overcome the inherently limited bandwidth of substrate-integrated waveguide (SIW) slot antennas. It is analytically shown that by decreasing the permittivity of a dielectric loaded slot antenna, the resulting bandwidth increases significantly, where the widest bandwidth can be achieved when the permittivity of the dielectric is less than unity. To demonstrate this concept, a rectangular SIW slot is loaded by an array of thin wires to realize the desired low-index metamaterials (MTMs), which consequently results in a single-layer, compact, and cost-effective structure. We have measured an impedance bandwidth <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo stretchy=\"false\">(</mo><mrow><mo stretchy=\"false\">|</mo></mrow><msub><mi>S</mi><mn>11</mn></msub><mrow><mo stretchy=\"false\">|</mo></mrow><mo><</mo><mo>−</mo><mn>10</mn><mspace width=\"0.2em\"></mspace><mi>dB</mi><mo stretchy=\"false\">)</mo></math> of 36.2%, covering the millimeter-wave (mmWave) frequency range of 19.7–28.4 GHz. The radiation efficiency is above 90%, providing at least 7.5 decibels relative to isotropic (dBi) gain through the entire frequency band, making it a potential candidate for industrial, scientific and medical (ISM) and/or automotive radar (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>24.125</mn><mtext>--</mtext><mn>24.25</mn></math> GHz) and 5G (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>24.25</mn><mtext>--</mtext><mn>28.35</mn></math> GHz). Measurements show that the proposed antenna not only has a broad impedance bandwidth but also an improved radiation bandwidth.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"13 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139423990","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 : 2024-01-10DOI: 10.1103/physrevapplied.21.014015
Rhys G. Povey, Ming-Han Chou, Gustav Andersson, Christopher R. Conner, Joel Grebel, Yash J. Joshi, Jacob M. Miller, Hong Qiao, Xuntao Wu, Haoxiong Yan, Andrew N. Cleland
In the field of quantum computation and communication, there is a compelling need for quantum coherent frequency conversion between microwave electronics and infrared optics. A promising platform for this is an optomechanical crystal resonator that uses simultaneous photonic and phononic crystals to create a colocalized cavity coupling an electromagnetic mode to an acoustic mode, which then via electromechanical interactions can undergo direct transduction to electronics. The majority of the work in this area has been on one-dimensional nanobeam resonators, which provide strong optomechanical couplings but, due to their geometry, suffer from an inability to dissipate heat produced by the laser pumping required for operation. Recently, a quasi-two-dimensional optomechanical crystal cavity has been developed in silicon, exhibiting similarly strong coupling with better thermalization but at a mechanical frequency above optimal qubit operating frequencies. Here, we adapt this design to gallium arsenide, a natural thin-film single-crystal piezoelectric that can incorporate electromechanical interactions, obtaining a mechanical resonant mode at that is ideal for superconducting qubits and demonstrating optomechanical coupling of .
{"title":"Two-dimensional optomechanical crystal resonator in gallium arsenide","authors":"Rhys G. Povey, Ming-Han Chou, Gustav Andersson, Christopher R. Conner, Joel Grebel, Yash J. Joshi, Jacob M. Miller, Hong Qiao, Xuntao Wu, Haoxiong Yan, Andrew N. Cleland","doi":"10.1103/physrevapplied.21.014015","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014015","url":null,"abstract":"In the field of quantum computation and communication, there is a compelling need for quantum coherent frequency conversion between microwave electronics and infrared optics. A promising platform for this is an optomechanical crystal resonator that uses simultaneous photonic and phononic crystals to create a colocalized cavity coupling an electromagnetic mode to an acoustic mode, which then via electromechanical interactions can undergo direct transduction to electronics. The majority of the work in this area has been on one-dimensional nanobeam resonators, which provide strong optomechanical couplings but, due to their geometry, suffer from an inability to dissipate heat produced by the laser pumping required for operation. Recently, a quasi-two-dimensional optomechanical crystal cavity has been developed in silicon, exhibiting similarly strong coupling with better thermalization but at a mechanical frequency above optimal qubit operating frequencies. Here, we adapt this design to gallium arsenide, a natural thin-film single-crystal piezoelectric that can incorporate electromechanical interactions, obtaining a mechanical resonant mode at <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>f</mi><mi mathvariant=\"normal\">m</mi></msub><mo>≈</mo><mn>4.5</mn><mspace width=\"0.2em\"></mspace><mi>GHz</mi></math> that is ideal for superconducting qubits and demonstrating optomechanical coupling of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>g</mi><mi>om</mi></msub><mo>/</mo><mo stretchy=\"false\">(</mo><mn>2</mn><mi>π</mi><mo stretchy=\"false\">)</mo><mo>≈</mo><mn>650</mn><mspace width=\"0.2em\"></mspace><mi>kHz</mi></math>.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"41 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464139","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 : 2024-01-10DOI: 10.1103/physrevapplied.21.014014
Isaac Labrie-Boulay, Thomas Brian Winkler, Daniel Franzen, Alena Romanova, Hans Fangohr, Mathias Kläui
One of the most important magnetic spin structures is the topologically stabilized skyrmion quasiparticle. Its interesting physical properties make it a candidate for memory and efficient neuromorphic computation schemes. For device operation, the detection of the position, shape, and size of skyrmions is required and magnetic imaging is typically employed. A frequently used technique is magneto-optical Kerr microscopy, in which, depending on the sample’s material composition, temperature, material growing procedures, etc., the measurements suffer from noise, low contrast, intensity gradients, or other optical artifacts. Conventional image analysis packages require manual treatment, and a more automatic solution is required. We report a convolutional neural network specifically designed for segmentation problems to detect the position and shape of skyrmions in our measurements. The network is tuned using selected techniques to optimize predictions and, in particular, the number of detected classes is found to govern the performance. The results of this study show that a well-trained network is a viable method of automating data preprocessing in magnetic microscopy. The approach is easily extendable to other spin structures and other magnetic imaging methods.
{"title":"Machine-learning-based detection of spin structures","authors":"Isaac Labrie-Boulay, Thomas Brian Winkler, Daniel Franzen, Alena Romanova, Hans Fangohr, Mathias Kläui","doi":"10.1103/physrevapplied.21.014014","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014014","url":null,"abstract":"One of the most important magnetic spin structures is the topologically stabilized skyrmion quasiparticle. Its interesting physical properties make it a candidate for memory and efficient neuromorphic computation schemes. For device operation, the detection of the position, shape, and size of skyrmions is required and magnetic imaging is typically employed. A frequently used technique is magneto-optical Kerr microscopy, in which, depending on the sample’s material composition, temperature, material growing procedures, etc., the measurements suffer from noise, low contrast, intensity gradients, or other optical artifacts. Conventional image analysis packages require manual treatment, and a more automatic solution is required. We report a convolutional neural network specifically designed for segmentation problems to detect the position and shape of skyrmions in our measurements. The network is tuned using selected techniques to optimize predictions and, in particular, the number of detected classes is found to govern the performance. The results of this study show that a well-trained network is a viable method of automating data preprocessing in magnetic microscopy. The approach is easily extendable to other spin structures and other magnetic imaging methods.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"12 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139420498","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}
Spin-orbit torque (SOT) has great potential application for developing next-generation magnetic random-access memory (MRAM). For efficient utilization of the SOT MRAM, most efforts have been focused on reducing power consumption by improving the SOT efficiency. Here, we report that inserting an ultrathin <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math> (or <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Pt</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math>) layer at the heavy-metal–ferromagnet interface is an effective strategy to increase the SOT efficiency. By performing spin-torque ferromagnetic magnetic resonance and second-harmonic Hall measurements, we found that the absolute values of the charge-to-spin conversion efficiency increase from 0.09 for annealed W-<math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Co</mi><mn>20</mn></msub><msub><mi>Fe</mi><mn>60</mn></msub><msub><mrow><mi mathvariant="normal">B</mi></mrow><mn>20</mn></msub></math> (CFB) sample to 0.15 for annealed <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">W</mi></mrow><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><mi>x</mi></mrow></msub></math>-CFB sample. The enhancement of the SOT efficiency can be attributed to the reduction of interfacial spin-memory loss at the annealed <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mi mathvariant="normal">W</mi></mrow></mrow><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math> (or <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Pt</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub><mo stretchy="false">)</mo><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><mi>CFB</mi></math> samples. Moreover, current-driven magnetization switching with a reduced critical current density has been achieved in the annealed <math display="inline" overflow="scroll" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mi mathvariant="normal">W</mi></mrow></mrow><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub><mstyle displaystyle="false" scriptlevel="0"><mtext>−</mtext></mstyle><mi>CFB</mi></math> samples. This study highlights the
自旋轨道力矩（SOT）在开发新一代磁性随机存取存储器（MRAM）方面具有巨大的应用潜力。为了有效利用 SOT MRAM，大多数人都致力于通过提高 SOT 效率来降低功耗。在此，我们报告了在重金属-铁磁体界面插入超薄 IrxMn1-x（或 PtxMn1-x）层是提高 SOT 效率的有效策略。通过自旋扭矩铁磁共振和二次谐波霍尔测量，我们发现电荷-自旋转换效率的绝对值从退火 W-Co20Fe60B20 (CFB) 样品的 0.09 提高到退火 W-IrxMn1-x-CFB 样品的 0.15。SOT 效率的提高可归因于退火 W-IrxMn1-x（或 PtxMn1-x）-CFB 样品界面自旋记忆损失的减少。此外，在退火的 W-IrxMn1-x-CFB 样品中还实现了临界电流密度降低的电流驱动磁化切换。这项研究强调了 IrxMn1-x（或 PtxMn1-x）插入层对提高 SOT 效率的重要作用，并提供了一种通过对 IrxMn1-x（或 PtxMn1-x）插入层进行纳米工程来提高 SOT 效率的策略，从而实现高能效 SOT 器件。
{"title":"Enhanced Spin-Orbit-Torque Efficiency inW−Co20Fe60B20Multilayers by Insertion of anIrxMn1−xorPtxMn1−xLayer","authors":"Qingtao Xia, Junda Qu, Tianren Luo, Dandan Zhang, Jin Cui, Houyi Cheng, Kewen Shi, Huaiwen Yang, Xueying Zhang, Qiang Li, Sylvain Eimer, Cong Wang, Dapeng Zhu, Weisheng Zhao","doi":"10.1103/physrevapplied.21.014016","DOIUrl":"https://doi.org/10.1103/physrevapplied.21.014016","url":null,"abstract":"Spin-orbit torque (SOT) has great potential application for developing next-generation magnetic random-access memory (MRAM). For efficient utilization of the SOT MRAM, most efforts have been focused on reducing power consumption by improving the SOT efficiency. Here, we report that inserting an ultrathin <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math> (or <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Pt</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math>) layer at the heavy-metal–ferromagnet interface is an effective strategy to increase the SOT efficiency. By performing spin-torque ferromagnetic magnetic resonance and second-harmonic Hall measurements, we found that the absolute values of the charge-to-spin conversion efficiency increase from 0.09 for annealed W-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Co</mi><mn>20</mn></msub><msub><mi>Fe</mi><mn>60</mn></msub><msub><mrow><mi mathvariant=\"normal\">B</mi></mrow><mn>20</mn></msub></math> (CFB) sample to 0.15 for annealed <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">W</mi></mrow><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><mi>x</mi></mrow></msub></math>-CFB sample. The enhancement of the SOT efficiency can be attributed to the reduction of interfacial spin-memory loss at the annealed <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mi mathvariant=\"normal\">W</mi></mrow></mrow><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub></math> (or <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Pt</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub><mo stretchy=\"false\">)</mo><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><mi>CFB</mi></math> samples. Moreover, current-driven magnetization switching with a reduced critical current density has been achieved in the annealed <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mi mathvariant=\"normal\">W</mi></mrow></mrow><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><msub><mi>Ir</mi><mi>x</mi></msub><msub><mi>Mn</mi><mrow><mn>1</mn><mtext>−</mtext><mi>x</mi></mrow></msub><mstyle displaystyle=\"false\" scriptlevel=\"0\"><mtext>−</mtext></mstyle><mi>CFB</mi></math> samples. This study highlights the ","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"54 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139423641","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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