Pub Date : 2024-08-08DOI: 10.1103/physrevapplied.22.024025
M. Khalifa, P. Feldmann, J. Salfi
Parametric converters are parametric amplifiers that mix two spatially separate nondegenerate modes and are commonly used for amplifying and squeezing microwave signals in quantum computing and sensing. In Josephson parametric converters, the strong localized nonlinearity of the Josephson junction limits the amplification and squeezing, as well as the dynamic range, in current devices. In contrast, a weak distributed nonlinearity can provide higher gain and dynamic range, when implemented as a kinetic inductance (KI) nanowire of a dirty superconductor, and has additional benefits such as resilience to magnetic field, higher-temperature operation, and simplified fabrication. Here, we propose, demonstrate, and analyze the performance of a KI parametric converter that relies on the weak distributed nonlinearity of a Nb-Ti-N KI nanowire. The device utilizes three-wave mixing induced by a dc current bias. We demonstrate its operation as a nondegenerate parametric amplifier with high phase-sensitive gain, reaching two-mode amplification and deamplification of approximately 30 dB for two resonances separated by 0.8 GHz, in excellent agreement with our theory of the device. We observe a dynamic range of dBm at 30 dB gain. Our device can significantly broaden applications of quantum-limited signal processing devices including phase-preserving amplification and two-mode squeezing.
参量转换器是一种参量放大器，它混合了两个空间上独立的非退行模式，通常用于放大和挤压量子计算和传感中的微波信号。在约瑟夫森参数转换器中，约瑟夫森结的强局部非线性限制了当前设备的放大和挤压以及动态范围。与此相反，弱分布式非线性可以提供更高的增益和动态范围，当作为脏超导体的动电感（KI）纳米线实现时，还具有抗磁场、更高温度操作和简化制造等额外优势。在此，我们提出、演示并分析了一种 KI 参数转换器的性能，该转换器依赖于 Nb-Ti-N KI 纳米线的微弱分布式非线性。该器件利用直流电流偏压诱导的三波混合。我们展示了它作为具有高相位敏感增益的非衰减参量放大器的运行情况，在两个相隔 0.8 GHz 的谐振中，它的双模放大和去放大率约为 30 dB，与我们的器件理论非常吻合。我们观察到 30 dB 增益时的动态范围为 -108 dBm。我们的器件可以大大拓宽量子限幅信号处理器件的应用范围，包括保相放大和双模挤压。
{"title":"Kinetic inductance parametric converter","authors":"M. Khalifa, P. Feldmann, J. Salfi","doi":"10.1103/physrevapplied.22.024025","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024025","url":null,"abstract":"Parametric converters are parametric amplifiers that mix two spatially separate nondegenerate modes and are commonly used for amplifying and squeezing microwave signals in quantum computing and sensing. In Josephson parametric converters, the strong localized nonlinearity of the Josephson junction limits the amplification and squeezing, as well as the dynamic range, in current devices. In contrast, a weak distributed nonlinearity can provide higher gain and dynamic range, when implemented as a kinetic inductance (KI) nanowire of a dirty superconductor, and has additional benefits such as resilience to magnetic field, higher-temperature operation, and simplified fabrication. Here, we propose, demonstrate, and analyze the performance of a KI parametric converter that relies on the weak distributed nonlinearity of a Nb-Ti-N KI nanowire. The device utilizes three-wave mixing induced by a dc current bias. We demonstrate its operation as a nondegenerate parametric amplifier with high phase-sensitive gain, reaching two-mode amplification and deamplification of approximately 30 dB for two resonances separated by 0.8 GHz, in excellent agreement with our theory of the device. We observe a dynamic range of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>−</mo><mn>108</mn></math> dBm at 30 dB gain. Our device can significantly broaden applications of quantum-limited signal processing devices including phase-preserving amplification and two-mode squeezing.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"22 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949311","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 : 2024-08-08DOI: 10.1103/physrevapplied.22.024020
Matteo Castellani, Owen Medeiros, Reed A. Foster, Alessandro Buzzi, Marco Colangelo, Joshua C. Bienfang, Alessandro Restelli, Karl K. Berggren
Decreasing the number of cables that bring heat into the cryostat is a critical issue for all cryoelectronic devices. In particular, arrays of superconducting nanowire single-photon detectors (SNSPDs) could require more than readout lines. Performing signal-processing operations at low temperatures could be a solution. Nanocryotrons, superconducting nanowire three-terminal devices, are good candidates for integrating sensing and electronics on the same technological platform as SNSPDs in photon-counting applications. In this work, we demonstrate that it is possible to read out, process, encode, and store the output of SNSPDs using exclusively superconducting nanowires patterned on niobium nitride thin films. In particular, we present the design and development of a nanocryotron ripple counter that detects input voltage spikes and converts the number of pulses to an -digit value. The counting base can be tuned from 2 to higher values, enabling higher maximum counts without enlarging the circuit. As a proof of principle, we first experimentally demonstrate the building block of the counter, an integer- frequency divider with ranging from 2 to 5. Then, we demonstrate photon-counting operations at 405 nm and 1550 nm by coupling an SNSPD with a two-digit nanocryotron counter partially integrated on chip. The two-digit counter can operate in either base 2 or base 3, with a bit-error rate lower than and a count rate of . We simulate circuit architectures for integrated readout of the counter state and we evaluate the capabilities of reading out an SNSPD megapixel array that would collect up to counts per second. The results of this work, combined with our recent publications on a nanocryotron shift register and logic gates, pave the way for the development of nanocryotron processors, from which multiple superconducting platforms may benefit.
{"title":"Nanocryotron ripple counter integrated with a superconducting nanowire single-photon detector for megapixel arrays","authors":"Matteo Castellani, Owen Medeiros, Reed A. Foster, Alessandro Buzzi, Marco Colangelo, Joshua C. Bienfang, Alessandro Restelli, Karl K. Berggren","doi":"10.1103/physrevapplied.22.024020","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024020","url":null,"abstract":"Decreasing the number of cables that bring heat into the cryostat is a critical issue for all cryoelectronic devices. In particular, arrays of superconducting nanowire single-photon detectors (SNSPDs) could require more than <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>6</mn></msup></math> readout lines. Performing signal-processing operations at low temperatures could be a solution. Nanocryotrons, superconducting nanowire three-terminal devices, are good candidates for integrating sensing and electronics on the same technological platform as SNSPDs in photon-counting applications. In this work, we demonstrate that it is possible to read out, process, encode, and store the output of SNSPDs using exclusively superconducting nanowires patterned on niobium nitride thin films. In particular, we present the design and development of a nanocryotron ripple counter that detects input voltage spikes and converts the number of pulses to an <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math>-digit value. The counting base can be tuned from 2 to higher values, enabling higher maximum counts without enlarging the circuit. As a proof of principle, we first experimentally demonstrate the building block of the counter, an integer-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math> frequency divider with <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math> ranging from 2 to 5. Then, we demonstrate photon-counting operations at 405 nm and 1550 nm by coupling an SNSPD with a two-digit nanocryotron counter partially integrated on chip. The two-digit counter can operate in either base 2 or base 3, with a bit-error rate lower than <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math> and a count rate of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>7</mn></msup><mspace width=\"0.2em\"></mspace><msup><mrow><mrow><mi mathvariant=\"normal\">s</mi></mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. We simulate circuit architectures for integrated readout of the counter state and we evaluate the capabilities of reading out an SNSPD megapixel array that would collect up to <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>12</mn></msup></math> counts per second. The results of this work, combined with our recent publications on a nanocryotron shift register and logic gates, pave the way for the development of nanocryotron processors, from which multiple superconducting platforms may benefit.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"28 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949313","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 : 2024-08-08DOI: 10.1103/physrevapplied.22.024024
G. Laloy-Borgna, L. Vovard, A. Rohfritsch, L. Wang, J. Ngo, M. Perier, A. Drainville, F. Prat, M. Lafond, C. Lafon, S. Catheline
Pancreatic ductal adenocarcinoma is a devastating disease with very low survival rates 5 years after diagnosis. The main reason for this dismal prognosis is the thick stroma which both protects tumor cells from drug penetration and supports tumor development. Ultrasound inertial cavitation is a promising treatment with potential for stromal disruption, enhancing tumor cells’ sensitivity to chemical agents and biomodulators. Our goal was to develop a dedicated microelastography setup allowing us to measure the elasticity of in vitro tumor models called spheroids. In a second step, the impact of cavitation treatment on their mechanical properties was assessed. A transcranial magnetic stimulation clinical device was used to induce shear waves in the spheroids containing magnetic nanoparticles. Using an inverted optical microscope, particle imaging velocimetry, and noise correlation algorithms, the shear wave velocity, indicative of the medium’s elasticity, could be measured. Shear waves generated by the magnetic pulse inside the spheroids were detected and their velocity was measured using noise correlation elastography. This allowed the estimation of the spheroids’ elasticity. Cavitation treatment softened them significantly, and the impact of the exposure conditions and the spheroids’ composition have been studied. In the future, such a method could be used to monitor cavitation treatments. In addition, since it is now well established that mechanical constraints and elasticity play an important role in tumor growth, it is of great interest to measure the elasticity of tumor models to better understand the mechanisms of tumor growth.
{"title":"Magnetic microelastography for evaluation of ultrasound-induced softening of pancreatic cancer spheroids","authors":"G. Laloy-Borgna, L. Vovard, A. Rohfritsch, L. Wang, J. Ngo, M. Perier, A. Drainville, F. Prat, M. Lafond, C. Lafon, S. Catheline","doi":"10.1103/physrevapplied.22.024024","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024024","url":null,"abstract":"Pancreatic ductal adenocarcinoma is a devastating disease with very low survival rates 5 years after diagnosis. The main reason for this dismal prognosis is the thick stroma which both protects tumor cells from drug penetration and supports tumor development. Ultrasound inertial cavitation is a promising treatment with potential for stromal disruption, enhancing tumor cells’ sensitivity to chemical agents and biomodulators. Our goal was to develop a dedicated microelastography setup allowing us to measure the elasticity of <i>in vitro</i> tumor models called spheroids. In a second step, the impact of cavitation treatment on their mechanical properties was assessed. A transcranial magnetic stimulation clinical device was used to induce shear waves in the spheroids containing magnetic nanoparticles. Using an inverted optical microscope, particle imaging velocimetry, and noise correlation algorithms, the shear wave velocity, indicative of the medium’s elasticity, could be measured. Shear waves generated by the magnetic pulse inside the spheroids were detected and their velocity was measured using noise correlation elastography. This allowed the estimation of the spheroids’ elasticity. Cavitation treatment softened them significantly, and the impact of the exposure conditions and the spheroids’ composition have been studied. In the future, such a method could be used to monitor cavitation treatments. In addition, since it is now well established that mechanical constraints and elasticity play an important role in tumor growth, it is of great interest to measure the elasticity of tumor models to better understand the mechanisms of tumor growth.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"74 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949312","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 : 2024-08-08DOI: 10.1103/physrevapplied.22.024026
Elizabeth Robertson, Luisa Esguerra, Leon Meßner, Guillermo Gallego, Janik Wolters
Efficient optical quantum memories are a milestone required for several quantum technologies, including repeater-based quantum key distribution and on-demand multiphoton generation. We present an efficiency optimization of an optical electromagnetically induced transparency (EIT) memory experiment in a warm cesium vapor using a genetic algorithm and analyze the resulting wave forms. The control pulse is represented either as a Gaussian or free-form pulse and the results from the optimization are compared. We see an improvement factor of 3(7)% when using optimized free-form pulses. By limiting the allowed pulse energy in a solution, we show an energy-based optimization giving a 30% reduction in energy, with minimal efficiency loss.
{"title":"Machine-learning optimal control pulses in an optical quantum memory experiment","authors":"Elizabeth Robertson, Luisa Esguerra, Leon Meßner, Guillermo Gallego, Janik Wolters","doi":"10.1103/physrevapplied.22.024026","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024026","url":null,"abstract":"Efficient optical quantum memories are a milestone required for several quantum technologies, including repeater-based quantum key distribution and on-demand multiphoton generation. We present an efficiency optimization of an optical electromagnetically induced transparency (EIT) memory experiment in a warm cesium vapor using a genetic algorithm and analyze the resulting wave forms. The control pulse is represented either as a Gaussian or free-form pulse and the results from the optimization are compared. We see an improvement factor of 3(7)% when using optimized free-form pulses. By limiting the allowed pulse energy in a solution, we show an energy-based optimization giving a 30% reduction in energy, with minimal efficiency loss.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"75 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949310","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 : 2024-08-07DOI: 10.1103/physrevapplied.22.024018
Wenhai Liang, Shuman Du, Renjing Chen, Chengru Wu, Xiong Shen, Peng Wang, Jun Liu, Ruxin Li
Spatial gaps between sub-beams in high-peak-power lasers with tiled-aperture-based coherent beam combining (TACBC) give rise to relatively strong sidelobes and impair the power in bucket (PIB) at far field. To address the aforementioned issue, spatial chirp is employed in this paper to fill the gaps and further enhance PIB. With two sub-beams, both simulations and experiments indicate that spatial chirp can boost PIB by 1.8 times at a gap-beam width ratio of 0.2. The same enhancement is observed in simulations even when four sub-beams are considered. To put it briefly, the spatial-chirp-assisted TACBC approach holds the potential in boosting focal intensity during constructing tens to hundreds of petawatt (PW) lasers.
{"title":"Power-in-bucket enhancement in tiled-aperture coherent beam combining through inducing spatial chirp","authors":"Wenhai Liang, Shuman Du, Renjing Chen, Chengru Wu, Xiong Shen, Peng Wang, Jun Liu, Ruxin Li","doi":"10.1103/physrevapplied.22.024018","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024018","url":null,"abstract":"Spatial gaps between sub-beams in high-peak-power lasers with tiled-aperture-based coherent beam combining (TACBC) give rise to relatively strong sidelobes and impair the power in bucket (PIB) at far field<b>.</b> To address the aforementioned issue, spatial chirp is employed in this paper to fill the gaps and further enhance PIB. With two sub-beams, both simulations and experiments indicate that spatial chirp can boost PIB by 1.8 times at a gap-beam width ratio of 0.2. The same enhancement is observed in simulations even when four sub-beams are considered. To put it briefly, the spatial-chirp-assisted TACBC approach holds the potential in boosting focal intensity during constructing tens to hundreds of petawatt (PW) lasers.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"6 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949314","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 : 2024-08-07DOI: 10.1103/physrevapplied.22.024016
Anthony D’Addario, Johnathan Kuan, Noah F. Opondo, Ozan Erturk, Tao Zhou, Sunil A. Bhave, Martin V. Holt, Gregory D. Fuchs
Bulk-mode acoustic waves in a crystalline material exert lattice strain through the thickness of the sample, which couples to the spin Hamiltonian of defect-based qubits such as the nitrogen-vacancy (N-V) center defect in diamond. This mechanism has previously been harnessed for unconventional quantum spin control, spin decoherence protection, and quantum sensing. Bulk-mode acoustic wave devices are also important in the microelectronics industry as microwave filters. A key challenge in both applications is a lack of appropriate operando microscopy tools for quantifying and visualizing gigahertz-frequency dynamic strain. In this work, we directly image acoustic strain within N-V center-coupled diamond thin-film bulk acoustic wave resonators using stroboscopic scanning hard x-ray diffraction microscopy at the Advanced Photon Source. The far-field scattering patterns of the nanofocused x-ray diffraction encode strain information entirely through the illuminated thickness of the resonator. These patterns have a real-space spatial variation that is consistent with the bulk strain’s expected modal distribution and a momentum-space angular variation from which the strain amplitude can be quantitatively deduced. We also perform optical measurements of strain-driven Rabi precession of of the N-V center spin ensemble, providing an additional quantitative measurement of the strain amplitude. As a result, we directly measure one of the six N-V spin-stress coupling parameters, MHz/GPa, by correlating these measurements at the same spatial position and applied microwave power. Our results demonstrate a unique technique for directly imaging ac lattice strain in micromechanical structures and provide a direct measurement of a fundamental constant for the N-V center defect spin Hamiltonian.
晶体材料中的体模声波会通过样品的厚度产生晶格应变，这种应变会耦合到基于缺陷的量子比特（如金刚石中的氮-隙（N-V）中心缺陷）的自旋哈密顿。这种机制曾被用于非常规量子自旋控制、自旋退相干保护和量子传感。体模声波器件作为微波滤波器在微电子工业中也很重要。这两种应用中的一个关键挑战是缺乏适当的操作显微镜工具来量化和可视化千兆赫频率动态应变。在这项工作中，我们利用先进光子源的频闪扫描硬 X 射线衍射显微镜，直接对 N-V 中心耦合金刚石薄膜体声波谐振器内的声应变进行成像。纳米聚焦 X 射线衍射的远场散射图案完全通过谐振器的照射厚度编码应变信息。这些图案的实空间空间变化与块体应变的预期模态分布一致，而动量空间角度变化则可从中定量推导出应变振幅。我们还对 N-V 中心自旋合集的应变驱动拉比前驱进行了光学测量，为应变振幅提供了额外的定量测量。因此，通过在相同空间位置和应用微波功率下进行相关测量，我们直接测量了六个 N-V 自旋应力耦合参数之一 b=2.73(2) MHz/GPa。我们的研究结果展示了一种直接成像微机械结构中交流晶格应变的独特技术，并提供了对 N-V 中心缺陷自旋哈密顿基本常数的直接测量。
{"title":"Stroboscopic x-ray diffraction microscopy of dynamic strain in diamond thin-film bulk acoustic resonators for quantum control of nitrogen-vacancy centers","authors":"Anthony D’Addario, Johnathan Kuan, Noah F. Opondo, Ozan Erturk, Tao Zhou, Sunil A. Bhave, Martin V. Holt, Gregory D. Fuchs","doi":"10.1103/physrevapplied.22.024016","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024016","url":null,"abstract":"Bulk-mode acoustic waves in a crystalline material exert lattice strain through the thickness of the sample, which couples to the spin Hamiltonian of defect-based qubits such as the nitrogen-vacancy (N-<i>V</i>) center defect in diamond. This mechanism has previously been harnessed for unconventional quantum spin control, spin decoherence protection, and quantum sensing. Bulk-mode acoustic wave devices are also important in the microelectronics industry as microwave filters. A key challenge in both applications is a lack of appropriate operando microscopy tools for quantifying and visualizing gigahertz-frequency dynamic strain. In this work, we directly image acoustic strain within N-<i>V</i> center-coupled diamond thin-film bulk acoustic wave resonators using stroboscopic scanning hard x-ray diffraction microscopy at the Advanced Photon Source. The far-field scattering patterns of the nanofocused x-ray diffraction encode strain information entirely through the illuminated thickness of the resonator. These patterns have a real-space spatial variation that is consistent with the bulk strain’s expected modal distribution and a momentum-space angular variation from which the strain amplitude can be quantitatively deduced. We also perform optical measurements of strain-driven Rabi precession of of the N-<i>V</i> center spin ensemble, providing an additional quantitative measurement of the strain amplitude. As a result, we directly measure one of the six N-<i>V</i> spin-stress coupling parameters, <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>b</mi><mo>=</mo><mn>2.73</mn><mo stretchy=\"false\">(</mo><mn>2</mn><mo stretchy=\"false\">)</mo></math> MHz/GPa, by correlating these measurements at the same spatial position and applied microwave power. Our results demonstrate a unique technique for directly imaging ac lattice strain in micromechanical structures and provide a direct measurement of a fundamental constant for the N-<i>V</i> center defect spin Hamiltonian.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"36 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949368","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 : 2024-08-07DOI: 10.1103/physrevapplied.22.024019
C.K. Safeer, Paul S. Keatley, Witold Skowroński, Jakub Mojsiejuk, Kay Yakushiji, Akio Fukushima, Shinji Yuasa, Daniel Bedau, Fèlix Casanova, Luis E. Hueso, Robert J. Hicken, Daniele Pinna, Gerrit van der Laan, Thorsten Hesjedal
Understanding the high-frequency transport characteristics of magnetic tunnel junctions (MTJs) is crucial for the development of fast-operating spintronics memories and radio frequency devices. Here, we present the study of a frequency-dependent capacitive current effect in -based MTJs and its influence on magnetization dynamics using a time-resolved magneto-optical Kerr effect technique. In our device, operating at gigahertz frequencies, we find a large displacement current of the order of mA, which does not break the tunnel barrier of the MTJ. Importantly, this current generates an Oersted field and spin-orbit torque, inducing magnetization dynamics. Our discovery holds promise for building robust MTJ devices operating under high current conditions, also highlighting the significance of capacitive impedance in high-frequency magnetotransport techniques.
{"title":"Magnetization dynamics driven by displacement currents across a magnetic tunnel junction","authors":"C.K. Safeer, Paul S. Keatley, Witold Skowroński, Jakub Mojsiejuk, Kay Yakushiji, Akio Fukushima, Shinji Yuasa, Daniel Bedau, Fèlix Casanova, Luis E. Hueso, Robert J. Hicken, Daniele Pinna, Gerrit van der Laan, Thorsten Hesjedal","doi":"10.1103/physrevapplied.22.024019","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024019","url":null,"abstract":"Understanding the high-frequency transport characteristics of magnetic tunnel junctions (MTJs) is crucial for the development of fast-operating spintronics memories and radio frequency devices. Here, we present the study of a frequency-dependent capacitive current effect in <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Co</mi><mi>Fe</mi><mi mathvariant=\"normal\">B</mi></mrow><mo>/</mo><mrow><mi>Mg</mi><mi mathvariant=\"normal\">O</mi></mrow></math>-based MTJs and its influence on magnetization dynamics using a time-resolved magneto-optical Kerr effect technique. In our device, operating at gigahertz frequencies, we find a large displacement current of the order of mA, which does not break the tunnel barrier of the MTJ. Importantly, this current generates an Oersted field and spin-orbit torque, inducing magnetization dynamics. Our discovery holds promise for building robust MTJ devices operating under high current conditions, also highlighting the significance of capacitive impedance in high-frequency magnetotransport techniques.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"2 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949366","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 : 2024-08-07DOI: 10.1103/physrevapplied.22.024017
Taha Y. Posos, Jack Cook, Sergey V. Baryshev
Large-area carbon-nanotube (CNT) cathodes made from yarns, films, or fibers have long been promising as next-generation electron sources for high-power rf and microwave-vacuum-electronic devices. However, experimental evidence has highlighted that spatial incoherence of the electron beam produced by such cathodes impeded the progress toward high brightness CNT electron sources and their practical applications. Indeed, typically large-area CNT fibers, films, or textiles emit stochastically across their physical surface at large emission angles and with large transverse spread, meaning large emittance and hence low brightness. In this work, using high-resolution field-emission microscopy, we demonstrate that conventional electroplating of hair-thick CNT fibers followed by a femtosecond laser cutting, producing an emitter surface, solves the described incoherent emission issues extremely well. Strikingly, it was observed that the entire (within the error margin) cathode surface of a radius of approximately emitted uniformly (with no hot spots) in the direction of the applied electric field. The normalized cathode emittance, i.e., on the fiber surface, was estimated as 26- with brightness of (or ) estimated for pulsed-mode operation.
{"title":"Bright spatially coherent beam from carbon-nanotube fiber field-emission cathode","authors":"Taha Y. Posos, Jack Cook, Sergey V. Baryshev","doi":"10.1103/physrevapplied.22.024017","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024017","url":null,"abstract":"Large-area carbon-nanotube (CNT) cathodes made from yarns, films, or fibers have long been promising as next-generation electron sources for high-power rf and microwave-vacuum-electronic devices. However, experimental evidence has highlighted that spatial incoherence of the electron beam produced by such cathodes impeded the progress toward high brightness CNT electron sources and their practical applications. Indeed, typically large-area CNT fibers, films, or textiles emit stochastically across their physical surface at large emission angles and with large transverse spread, meaning large emittance and hence low brightness. In this work, using high-resolution field-emission microscopy, we demonstrate that conventional electroplating of hair-thick CNT fibers followed by a femtosecond laser cutting, producing an emitter surface, solves the described incoherent emission issues extremely well. Strikingly, it was observed that the entire (within the error margin) cathode surface of a radius of approximately <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>75</mn><mspace width=\"0.2em\"></mspace><mtext fontfamily=\"times\">μ</mtext><mtext>m</mtext></math> emitted uniformly (with no hot spots) in the direction of the applied electric field. The normalized cathode emittance, i.e., on the fiber surface, was estimated as 26-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>nm</mtext><mspace width=\"0.2em\"></mspace><mtext>rad</mtext></math> with brightness of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>></mo><msup><mn>10</mn><mn>16</mn></msup><mspace width=\"0.2em\"></mspace><mtext>A</mtext><mo>/</mo><mrow><msup><mtext>m</mtext><mn>2</mn></msup><mspace width=\"0.2em\"></mspace><msup><mtext>rad</mtext><mn>2</mn></msup></mrow></math> (or <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>></mo><msup><mn>10</mn><mn>7</mn></msup><mspace width=\"0.2em\"></mspace><mrow><mi mathvariant=\"normal\">A</mi></mrow><mspace width=\"0.2em\"></mspace><msup><mrow><mi mathvariant=\"normal\">m</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mspace width=\"0.2em\"></mspace><msup><mi>sr</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><mspace width=\"0.2em\"></mspace><msup><mrow><mi mathvariant=\"normal\">V</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>) estimated for pulsed-mode operation.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"75 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949367","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.22.024012
Randy Lafler, Mark L. Eickhoff, Scott C. Newey, Yamil Nieves Gonzalez, Kurt E. Stoltenberg, J. Frank Camacho, Mark A. Harris, Denis W. Oesch, Adrian J. Lewis, R. Nicholas Lanning
High-precision remote clock synchronization is crucial for many classical and quantum network applications. Evaluating options for space-Earth links, we find that traditional solutions may not produce the desired synchronization for low Earth orbits and unnecessarily complicate quantum networking architectures. Demonstrating an alternative, we use commercial off-the-shelf quantum photon sources and detection equipment to synchronize two remote clocks across our free-space testbed utilizing a method called two-way quantum time transfer (QTT). We reach picosecond-scale timing precision under very lossy and noisy channel conditions representative of daytime space-Earth links and software-emulated satellite motion. This work demonstrates how QTT is potentially relevant for daytime space-Earth quantum networking and/or providing high-precision timing in GPS-denied environments.
{"title":"Two-way quantum time transfer: a method for daytime space-Earth links","authors":"Randy Lafler, Mark L. Eickhoff, Scott C. Newey, Yamil Nieves Gonzalez, Kurt E. Stoltenberg, J. Frank Camacho, Mark A. Harris, Denis W. Oesch, Adrian J. Lewis, R. Nicholas Lanning","doi":"10.1103/physrevapplied.22.024012","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024012","url":null,"abstract":"High-precision remote clock synchronization is crucial for many classical and quantum network applications. Evaluating options for space-Earth links, we find that traditional solutions may not produce the desired synchronization for low Earth orbits and unnecessarily complicate quantum networking architectures. Demonstrating an alternative, we use commercial off-the-shelf quantum photon sources and detection equipment to synchronize two remote clocks across our free-space testbed utilizing a method called two-way quantum time transfer (QTT). We reach picosecond-scale timing precision under very lossy and noisy channel conditions representative of daytime space-Earth links and software-emulated satellite motion. This work demonstrates how QTT is potentially relevant for daytime space-Earth quantum networking and/or providing high-precision timing in GPS-denied environments.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"2 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949376","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.22.024013
Edward Butler-Caddle, K.D.G. Imalka Jayawardena, Anjana Wijesekara, Rebecca L. Milot, James Lloyd-Hughes
In perovskite solar cells, photovoltaic action is created by charge transport layers (CTLs) either side of the light-absorbing metal halide perovskite semiconductor. Hence, the rates for desirable charge extraction and unwanted interfacial recombination at the perovskite-CTL interfaces play a critical role for device efficiency. Here, the electrical properties of perovskite-CTL bilayer heterostructures are obtained using ultrafast terahertz and optical studies of the charge carrier dynamics after pulsed photoexcitation, combined with a physical model of charge carrier transport that includes the prominent Coulombic forces that arise after selective charge extraction into a CTL, and cross-interfacial recombination. The charge extraction velocity at the interface and the ambipolar diffusion coefficient within the perovskite are determined from the experimental decay profiles for heterostructures with three of the highest-performing CTLs, namely , PCBM and Spiro-OMeTAD. Definitive targets for the further improvement of devices are deduced: fullerenes deliver fast electron extraction, but suffer from a large rate constant for cross-interface recombination or hole extraction. Conversely, Spiro-OMeTAD exhibits slow hole extraction but does not increase the perovskite’s surface recombination rate, likely contributing to its success in solar cell devices.
{"title":"Distinguishing carrier transport and interfacial recombination at perovskite/transport-layer interfaces using ultrafast spectroscopy and numerical simulation","authors":"Edward Butler-Caddle, K.D.G. Imalka Jayawardena, Anjana Wijesekara, Rebecca L. Milot, James Lloyd-Hughes","doi":"10.1103/physrevapplied.22.024013","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024013","url":null,"abstract":"In perovskite solar cells, photovoltaic action is created by charge transport layers (CTLs) either side of the light-absorbing metal halide perovskite semiconductor. Hence, the rates for desirable charge extraction and unwanted interfacial recombination at the perovskite-CTL interfaces play a critical role for device efficiency. Here, the electrical properties of perovskite-CTL bilayer heterostructures are obtained using ultrafast terahertz and optical studies of the charge carrier dynamics after pulsed photoexcitation, combined with a physical model of charge carrier transport that includes the prominent Coulombic forces that arise after selective charge extraction into a CTL, and cross-interfacial recombination. The charge extraction velocity at the interface and the ambipolar diffusion coefficient within the perovskite are determined from the experimental decay profiles for heterostructures with three of the highest-performing CTLs, namely <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mtext>C</mtext><mn>60</mn></msub></math>, PCBM and Spiro-OMeTAD. Definitive targets for the further improvement of devices are deduced: fullerenes deliver fast electron extraction, but suffer from a large rate constant for cross-interface recombination or hole extraction. Conversely, Spiro-OMeTAD exhibits slow hole extraction but does not increase the perovskite’s surface recombination rate, likely contributing to its success in solar cell devices.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"14 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141949375","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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