Pub Date : 2024-09-12DOI: 10.1103/physrevapplied.22.034032
Ivan S. Sushchev, Daniil S. Bulavkin, Kirill E. Bugai, Anna S. Sidelnikova, Dmitriy A. Dvoretskiy
This paper presents a theoretical and experimental demonstration of a security analysis of a Trojan-horse attack (THA) on a real-world quantum key distribution (QKD) system. We show that the upper bound on the information leakage depends solely on the fidelity between the states of the adversary. We find the lower bound for fidelity between THA states in both the polarization- and phase-coding BB84 protocols, considering both pure and mixed states. Our bounds depend only on the mean photon number per pulse available to an adversary. We also present an experimental analysis of a QKD system, including optical time-domain reflectometry measurements with centimeter resolution and spectral transmittance measurements for optical defense elements ranging from 1100 to 1800 nm with a noise floor lower than dB. Finally, by considering the optimal attack, we obtain the value of the mean photon number per pulse available to an adversary and calculate the key leakage that needs to be eliminated during the privacy amplification procedure.
{"title":"Trojan-horse attack on a real-world quantum key distribution system: Theoretical and experimental security analysis","authors":"Ivan S. Sushchev, Daniil S. Bulavkin, Kirill E. Bugai, Anna S. Sidelnikova, Dmitriy A. Dvoretskiy","doi":"10.1103/physrevapplied.22.034032","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034032","url":null,"abstract":"This paper presents a theoretical and experimental demonstration of a security analysis of a Trojan-horse attack (THA) on a real-world quantum key distribution (QKD) system. We show that the upper bound on the information leakage depends solely on the fidelity between the states of the adversary. We find the lower bound for fidelity between THA states in both the polarization- and phase-coding BB84 protocols, considering both pure and mixed states. Our bounds depend only on the mean photon number per pulse available to an adversary. We also present an experimental analysis of a QKD system, including optical time-domain reflectometry measurements with centimeter resolution and spectral transmittance measurements for optical defense elements ranging from 1100 to 1800 nm with a noise floor lower than <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>−</mo><mn>100</mn></math> dB. Finally, by considering the optimal attack, we obtain the value of the mean photon number per pulse available to an adversary and calculate the key leakage that needs to be eliminated during the privacy amplification procedure.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"31 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185204","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 : 2024-09-12DOI: 10.1103/physrevapplied.22.034034
Bhawna Sahni, Aftab Alam
Double half-Heusler (HH) alloys are a new class of compounds that can be seen as transmuted versions of two single half-Heusler alloys with higher flexibility of tunability of their properties. Here, we report a detailed study of the thermoelectric (TE) properties of two double HH alloys ( = , ), using first-principles calculation. These alloys exhibit a rich phase diagram with the possibility of tetragonal, cubic, and solid-solution phases. As such, a comparative study of the TE properties of all these phases is highly desired. The simulated band gap, obtained using a hybrid functional, of the ordered phase of and lies in the range 0.24–0.4 and 0.17–0.59 eV, respectively, while, for the disordered phase, it lies in between 0.05 and 0.06 eV. A simulated TE figure of merit () as high as 2.02 and 2.45 is obtained for and , respectively. In both compounds, electronic transport plays the dominant role in achieving the promising values. We believe this study will attract the attention not only of experimentalists but also of theoreticians from the thermoelectric community to further investigate similar double HH alloys.
{"title":"Double half-Heusler alloys X2Ni2InSb (X = Zr, Hf) with promising thermoelectric performance: The role of varying structural phases","authors":"Bhawna Sahni, Aftab Alam","doi":"10.1103/physrevapplied.22.034034","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034034","url":null,"abstract":"Double half-Heusler (HH) alloys are a new class of compounds that can be seen as transmuted versions of two single half-Heusler alloys with higher flexibility of tunability of their properties. Here, we report a detailed study of the thermoelectric (TE) properties of two double HH alloys <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>X</mi><mn>2</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub><mi>InSb</mi></math> (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>X</mi></math> = <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Hf</mi></math>, <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Zr</mi></math>), using first-principles calculation. These alloys exhibit a rich phase diagram with the possibility of tetragonal, cubic, and solid-solution phases. As such, a comparative study of the TE properties of all these phases is highly desired. The simulated band gap, obtained using a hybrid functional, of the ordered phase of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Hf</mi><mn>2</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub><mi>InSb</mi></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Zr</mi><mn>2</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub><mi>InSb</mi></math> lies in the range 0.24–0.4 and 0.17–0.59 eV, respectively, while, for the disordered phase, it lies in between 0.05 and 0.06 eV. A simulated TE figure of merit (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Z</mi><mi>T</mi></math>) as high as 2.02 and 2.45 is obtained for <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Hf</mi><mn>2</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub><mi>InSb</mi></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Zr</mi><mn>2</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub><mi>InSb</mi></math>, respectively. In both compounds, electronic transport plays the dominant role in achieving the promising <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Z</mi><mi>T</mi></math> values. We believe this study will attract the attention not only of experimentalists but also of theoreticians from the thermoelectric community to further investigate similar double HH alloys.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"71 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185327","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 : 2024-09-11DOI: 10.1103/physrevapplied.22.034024
Mingze Wu, Junhui Li, Bingjie Xu, Song Yu, Yichen Zhang
Discrete-modulated continuous-variable quantum key distribution offers a pragmatic solution, greatly simplifying experimental procedures, while retaining robust integration with classical optical communication. Theoretical analyses have progressively validated the comprehensive security of this protocol, paving the way for practical experimentation. However, imperfect sources in practical implementations introduce noise. The traditional approach is to assume that eavesdroppers can control all of the source noise, which overestimates the ability of eavesdroppers and underestimates the secret-key rate. Some parts of source noise are intrinsic and cannot be manipulated by the eavesdropper, so they can be seen as trusted noise. We tailor a trusted-noise model specifically for the discrete-modulated protocol and upgrade the security analysis accordingly. Simulation results demonstrate that this approach successfully mitigates the negative impact of an imperfect source on system performance, while maintaining security of the protocol. Furthermore, our method can be used in conjunction with a trusted-detector-noise model, effectively reducing the influence of both source noise and detector noise in the experimental setup. This is a meaningful contribution to the practical deployment of discrete-modulated-continuous-variable-quantum-key-distribution systems.
{"title":"Trusted-source-noise model of discrete-modulated continuous-variable quantum key distribution","authors":"Mingze Wu, Junhui Li, Bingjie Xu, Song Yu, Yichen Zhang","doi":"10.1103/physrevapplied.22.034024","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034024","url":null,"abstract":"Discrete-modulated continuous-variable quantum key distribution offers a pragmatic solution, greatly simplifying experimental procedures, while retaining robust integration with classical optical communication. Theoretical analyses have progressively validated the comprehensive security of this protocol, paving the way for practical experimentation. However, imperfect sources in practical implementations introduce noise. The traditional approach is to assume that eavesdroppers can control all of the source noise, which overestimates the ability of eavesdroppers and underestimates the secret-key rate. Some parts of source noise are intrinsic and cannot be manipulated by the eavesdropper, so they can be seen as trusted noise. We tailor a trusted-noise model specifically for the discrete-modulated protocol and upgrade the security analysis accordingly. Simulation results demonstrate that this approach successfully mitigates the negative impact of an imperfect source on system performance, while maintaining security of the protocol. Furthermore, our method can be used in conjunction with a trusted-detector-noise model, effectively reducing the influence of both source noise and detector noise in the experimental setup. This is a meaningful contribution to the practical deployment of discrete-modulated-continuous-variable-quantum-key-distribution systems.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"310 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224191","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 : 2024-09-11DOI: 10.1103/physrevapplied.22.034027
M.P. Rosseto, S. Hurley, E.K. Lenzi, D.-K. Yang, R.S. Zola
Helical twists exist in liquid crystals as a result of the addition of chiral dopants or boundary conditions and play a role in several liquid-crystal phenomena and devices. To date, various methodologies have been explored, albeit with varying degrees of precision and complexity, often resulting in the measurement of just one parameter, such as helical sense. However, a consensus on the optimal technique remains elusive. We developed a technique to determine the total twist angle and handedness of the twist by using optical transmission spectroscopy. We present the theoretical background and experimental technique and test it against some other results and results from data published elsewhere. Furthermore, we investigate the use of three naturally occurring terpenoid materials as chiral dopants for liquid crystals and determine the helical handedness using the spectroscopy method.
{"title":"Determination of helical twist in liquid crystals: Examples and terpenoids as chiral dopants","authors":"M.P. Rosseto, S. Hurley, E.K. Lenzi, D.-K. Yang, R.S. Zola","doi":"10.1103/physrevapplied.22.034027","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034027","url":null,"abstract":"Helical twists exist in liquid crystals as a result of the addition of chiral dopants or boundary conditions and play a role in several liquid-crystal phenomena and devices. To date, various methodologies have been explored, albeit with varying degrees of precision and complexity, often resulting in the measurement of just one parameter, such as helical sense. However, a consensus on the optimal technique remains elusive. We developed a technique to determine the total twist angle and handedness of the twist by using optical transmission spectroscopy. We present the theoretical background and experimental technique and test it against some other results and results from data published elsewhere. Furthermore, we investigate the use of three naturally occurring terpenoid materials as chiral dopants for liquid crystals and determine the helical handedness using the spectroscopy method.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"62 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224194","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}
Growing interest in acoustic topological insulators arises from their robust edge states, which are resistant to defects and backscattering. Traditionally, the edge states of topological insulators are believed to be nearly immune to subwavelength-sized defects. As a result, there have been few studies focusing on utilizing defects to enhance wave control. Here, we investigate the impact of introducing periodic defects into acoustic pseudospin systems on the band structures and extend our analysis to nonperiodic structures. We discover that even a single subwavelength defect can significantly affect the topological boundary states, providing a platform for controlling and switching pseudospin edge states using defects. Expanding on this discovery, we develop a broadband topological sound switch (TSS) that achieves a high transmission ratio before and after switching by simply rotating a single scatterer. Additionally, we design three topological logic gates based on this TSS and experimentally verify their functionality. Our theory and experiments demonstrate that the spatial arrangement of defects can serve as a means of manipulating sound waves, potentially advancing acoustic computing and information processing.
{"title":"Topological logical elements based on defect-mediated sound-wave manipulation","authors":"Shi-Feng Li, Jie-Yu Lu, Cui-Yu-Yang Zhou, Xin-Ye Zou, Jian-Chun Cheng","doi":"10.1103/physrevapplied.22.034025","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034025","url":null,"abstract":"Growing interest in acoustic topological insulators arises from their robust edge states, which are resistant to defects and backscattering. Traditionally, the edge states of topological insulators are believed to be nearly immune to subwavelength-sized defects. As a result, there have been few studies focusing on utilizing defects to enhance wave control. Here, we investigate the impact of introducing periodic defects into acoustic pseudospin systems on the band structures and extend our analysis to nonperiodic structures. We discover that even a single subwavelength defect can significantly affect the topological boundary states, providing a platform for controlling and switching pseudospin edge states using defects. Expanding on this discovery, we develop a broadband topological sound switch (TSS) that achieves a high transmission ratio before and after switching by simply rotating a single scatterer. Additionally, we design three topological logic gates based on this TSS and experimentally verify their functionality. Our theory and experiments demonstrate that the spatial arrangement of defects can serve as a means of manipulating sound waves, potentially advancing acoustic computing and information processing.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"36 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185207","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 : 2024-09-11DOI: 10.1103/physrevapplied.22.034026
Yabin Jin, Wenjun Li, Bahram Djafari-Rouhani, Daniel Torrent, Yanxun Xiang, Fu-Zhen Xuan
We explore the exceptional points (EPs) in mass-spring oscillators with time-varying stiffness. The second-order EPs result from the coalescences of the fundamental and harmonic eigenmodes that can be achieved by a time modulation of the spring stiffness. The occurrence of EPs is first demonstrated in a theoretical model by solving the eigenvalue problem with the state-space method. The signature of the EP can be seen in the response spectrum when the system is subjected to an external excitation. The undamped and damped cases are both considered in this mass-spring oscillator, and the impact of the damping ratio and modulation amplitude on the EPs is systematically investigated. Based on an analogy of the equation of motion with the Mathieu differential equation, we discuss the stability of the undamped time-varying system under different modulation parameters and explore its connection to the EP phenomenon. As a typical property of a second-order EP, the square-root dependence of the frequency splitting response to a perturbation is studied by introducing an added mass. In a second part, the above theoretical concepts are established by simulation methods in an elastic solid mass-spring model and an equivalent time-varying stiffness is realized by shunting a piezoelectric patch with switch-controlled external negative capacitance circuits. This work should pave the way for applications of crack or perturbation detection in elastic media and inspire other elastic wave modulation functions in time-varying systems.
我们探讨了具有时变刚度的质量弹簧振荡器中的异常点（EPs）。二阶 EP 源自基波和谐波特征模态的凝聚，可通过对弹簧刚度进行时间调制来实现。通过使用状态空间法求解特征值问题，我们首先在理论模型中证明了 EP 的发生。当系统受到外部激励时，可以从响应谱中看到 EP 的特征。该质量弹簧振荡器同时考虑了无阻尼和有阻尼两种情况，并系统地研究了阻尼比和调制幅度对 EP 的影响。基于运动方程与马修微分方程的类比，我们讨论了无阻尼时变系统在不同调制参数下的稳定性，并探讨了其与 EP 现象的联系。作为二阶 EP 的典型特性，我们通过引入附加质量研究了频率分裂响应对扰动的平方根依赖性。在第二部分中，通过在弹性固体质量弹簧模型中的模拟方法建立了上述理论概念，并通过用开关控制的外部负电容电路分流压电贴片实现了等效时变刚度。这项工作将为弹性介质中裂纹或扰动检测的应用铺平道路，并对时变系统中的其他弹性波调制功能有所启发。
{"title":"Exceptional points in time-varying oscillators with enhanced sensing sensitivity","authors":"Yabin Jin, Wenjun Li, Bahram Djafari-Rouhani, Daniel Torrent, Yanxun Xiang, Fu-Zhen Xuan","doi":"10.1103/physrevapplied.22.034026","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034026","url":null,"abstract":"We explore the exceptional points (EPs) in mass-spring oscillators with time-varying stiffness. The second-order EPs result from the coalescences of the fundamental and harmonic eigenmodes that can be achieved by a time modulation of the spring stiffness. The occurrence of EPs is first demonstrated in a theoretical model by solving the eigenvalue problem with the state-space method. The signature of the EP can be seen in the response spectrum when the system is subjected to an external excitation. The undamped and damped cases are both considered in this mass-spring oscillator, and the impact of the damping ratio and modulation amplitude on the EPs is systematically investigated. Based on an analogy of the equation of motion with the Mathieu differential equation, we discuss the stability of the undamped time-varying system under different modulation parameters and explore its connection to the EP phenomenon. As a typical property of a second-order EP, the square-root dependence of the frequency splitting response to a perturbation is studied by introducing an added mass. In a second part, the above theoretical concepts are established by simulation methods in an elastic solid mass-spring model and an equivalent time-varying stiffness is realized by shunting a piezoelectric patch with switch-controlled external negative capacitance circuits. This work should pave the way for applications of crack or perturbation detection in elastic media and inspire other elastic wave modulation functions in time-varying systems.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"8 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185206","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}
Semiconductor - junctions with depletion zones have gained widespread use as a conventional way to give rise to electron asymmetric transmission. However, the approach is not applicable to monolayer graphene due to its characteristic feature of zero band gap. Asymmetric transmission in ballistic graphene therefore remains elusive to date. Here a simple approach based on the engineering of a four-layer array of quantum dots is proposed. Despite the array having few layers, it has the combined functionality of electron metasurfaces and band-gap materials with the symmetry breaking of spatial inversion, the extraordinary properties enabling electron asymmetric transmission. Our results open up the possibility of realizing electronic units dependent on the one-way effect and show great application potential with nearly perfect efficiency and simple design.
{"title":"Asymmetric transmission of electrons in ballistic graphene","authors":"Xin Tong, Ling Zhou, Ruihuang Zhao, Jiaxin Wang, Jinhu Luo, Junjie Du","doi":"10.1103/physrevapplied.22.l031003","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.l031003","url":null,"abstract":"Semiconductor <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>p</mi></math>-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>n</mi></math> junctions with depletion zones have gained widespread use as a conventional way to give rise to electron asymmetric transmission. However, the approach is not applicable to monolayer graphene due to its characteristic feature of zero band gap. Asymmetric transmission in ballistic graphene therefore remains elusive to date. Here a simple approach based on the engineering of a four-layer array of quantum dots is proposed. Despite the array having few layers, it has the combined functionality of electron metasurfaces and band-gap materials with the symmetry breaking of spatial inversion, the extraordinary properties enabling electron asymmetric transmission. Our results open up the possibility of realizing electronic units dependent on the one-way effect and show great application potential with nearly perfect efficiency and simple design.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"8 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224192","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 : 2024-09-10DOI: 10.1103/physrevapplied.22.l031004
Johann Ostmeyer, Tahereh Nematiaram, Alessandro Troisi, Pavel Buividovich
We present a first-principles numerical study of charge transport in a realistic two-dimensional tight-binding model of organic molecular semiconductors. We use the hybrid Monte Carlo (HMC) algorithm to simulate the full quantum dynamics of phonons and either single or multiple charge carriers without any tunable parameters. We introduce a number of algorithmic improvements, including efficient Metropolis updates for phonon fields based on analytical insights, which lead to negligible autocorrelation times and allow sub-per-mille precisions to be reached at a low computational cost of CPU hours. Our simulations produce charge-mobility estimates that are in good agreement with experiments and that also justify the phenomenological transient localization approach.
我们介绍了对有机分子半导体二维紧密结合模型中电荷传输的第一原理数值研究。我们使用混合蒙特卡洛（HMC）算法模拟声子和单个或多个电荷载流子的全部量子动力学，而无需任何可调参数。我们引入了一系列算法改进，包括基于分析见解的声子场高效 Metropolis 更新，这使得自相关时间可以忽略不计，并能以 O(1) 个 CPU 小时的低计算成本达到亚微米精度。我们的模拟得出的电荷流动性估计值与实验结果非常吻合，也证明了现象学瞬态定位方法的正确性。
{"title":"First-principles quantum Monte Carlo study of charge-carrier mobility in organic molecular semiconductors","authors":"Johann Ostmeyer, Tahereh Nematiaram, Alessandro Troisi, Pavel Buividovich","doi":"10.1103/physrevapplied.22.l031004","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.l031004","url":null,"abstract":"We present a first-principles numerical study of charge transport in a realistic two-dimensional tight-binding model of organic molecular semiconductors. We use the hybrid Monte Carlo (HMC) algorithm to simulate the full quantum dynamics of phonons and either single or multiple charge carriers without any tunable parameters. We introduce a number of algorithmic improvements, including efficient Metropolis updates for phonon fields based on analytical insights, which lead to negligible autocorrelation times and allow sub-per-mille precisions to be reached at a low computational cost of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mrow><mi mathvariant=\"script\">O</mi></mrow></mrow><mo></mo><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math> CPU hours. Our simulations produce charge-mobility estimates that are in good agreement with experiments and that also justify the phenomenological transient localization approach.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"59 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185208","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 : 2024-09-10DOI: 10.1103/physrevapplied.22.034021
Lin Cheng, Sheng-Chen Liu, Liang-You Peng, Qihuang Gong
The ability to perform entangling operations in parallel with a low error is essential for a large-scale fault-tolerant quantum computer. However, for trapped-ion systems, it is a challenging task due to the crosstalk resulting from the collective motional modes. Here, we develop a highly paralleled quantum circuit demonstrating a logical qubit based on the Steane code and study the impact of the crosstalk error on the performance of the fault-tolerant protocol. We show that the crosstalk indeed greatly destroys the fault-tolerant property of the quantum error correction. To achieve the break-even point with encoded qubits, we identify the suppression requirement of the crosstalk error to be less than for the Steane code. Furthermore, to mitigate the crosstalk below the fault-tolerant threshold, we propose a highly efficient optimization scheme by utilizing the programmable optical tweezer array. Overall, we make an elegant combination of the pulse-control optimization of parallel gate operations with the fault-tolerant protocol on the error-protected universal quantum computer.
{"title":"Crosstalk suppression of parallel gates for fault-tolerant quantum computation with trapped ions via optical tweezers","authors":"Lin Cheng, Sheng-Chen Liu, Liang-You Peng, Qihuang Gong","doi":"10.1103/physrevapplied.22.034021","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034021","url":null,"abstract":"The ability to perform entangling operations in parallel with a low error is essential for a large-scale fault-tolerant quantum computer. However, for trapped-ion systems, it is a challenging task due to the crosstalk resulting from the collective motional modes. Here, we develop a highly paralleled quantum circuit demonstrating a logical qubit based on the Steane code and study the impact of the crosstalk error on the performance of the fault-tolerant protocol. We show that the crosstalk indeed greatly destroys the fault-tolerant property of the quantum error correction. To achieve the break-even point with encoded qubits, we identify the suppression requirement of the crosstalk error to be less than <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> for the Steane code. Furthermore, to mitigate the crosstalk below the fault-tolerant threshold, we propose a highly efficient optimization scheme by utilizing the programmable optical tweezer array. Overall, we make an elegant combination of the pulse-control optimization of parallel gate operations with the fault-tolerant protocol on the error-protected universal quantum computer.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"62 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224224","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}
A novel high-energy electron radiography system combined with an active plasma lens (APL) has been designed for the first time and validated by simulation studies. The system consists of a 50-MeV electron linear accelerator followed by a 3-cm-long capillary with a discharge current up to hundreds of amperes. With the APL, the distance from the object plane to the imaging plane can be reduced from 5 m to 45 cm with a magnification factor (MF) of 20, and pictures with 1.1- spatial resolution can be obtained. The effects of lens chromatic aberrations, imaging blurring, and the uniformity of the plasma discharge current are shown to be significant in obtaining a high-spatial-resolution radiograph, which have been discussed in this work. Such a plasma-based imaging lens has a high tolerance for chromatic aberrations, is suitable for imaging thick target materials, and has radial symmetric focusing and adjustable focusing gradients. Furthermore, a cascaded high-MF radiography system based on APLs has been proposed to improve spatial resolution.
{"title":"High-energy electron radiography system with low chromatic aberrations based on active plasma lenses","authors":"Jie-Jie Lan, Quan-Tang Zhao, Zhang-Hu Hu, Zhao-Hui Ran, Wang-Wen Xu, Hao-Yuan Li, Jia Li, Shu-Chun Cao, Rui Cheng, Yong-Tao Zhao, Zi-Min Zhang, You-Nian Wang","doi":"10.1103/physrevapplied.22.034022","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.034022","url":null,"abstract":"A novel high-energy electron radiography system combined with an active plasma lens (APL) has been designed for the first time and validated by simulation studies. The system consists of a 50-MeV electron linear accelerator followed by a 3-cm-long capillary with a discharge current up to hundreds of amperes. With the APL, the distance from the object plane to the imaging plane can be reduced from 5 m to 45 cm with a magnification factor (MF) of 20, and pictures with 1.1-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext fontfamily=\"times\">μ</mtext><mrow><mi mathvariant=\"normal\">m</mi></mrow></math> spatial resolution can be obtained. The effects of lens chromatic aberrations, imaging blurring, and the uniformity of the plasma discharge current are shown to be significant in obtaining a high-spatial-resolution radiograph, which have been discussed in this work. Such a plasma-based imaging lens has a high tolerance for chromatic aberrations, is suitable for imaging thick target materials, and has radial symmetric focusing and adjustable focusing gradients. Furthermore, a cascaded high-MF radiography system based on APLs has been proposed to improve spatial resolution.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"71 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185209","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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