Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033260
Peter K. Morse, Paul J. Steinhardt, Salvatore Torquato
In previous work [Phys. Rev. X5, 021020 (2015)] it was shown that stealthy hyperuniform systems can be regarded as hard spheres in Fourier space in the sense that the structure factor is exactly zero in a spherical region around the origin in analogy with the pair-correlation function of real-space hard spheres. While this earlier work focused on spatial dimensions , here we extend the analysis to higher dimensions in order to make connections to high-dimensional sphere packings and the mean-field theory of glasses. We exploit this correspondence to confirm that the densest Fourier-space hard-sphere system is that of a Bravais lattice in contrast to real-space hard spheres, whose densest configuration is conjectured to be disordered. In passing, we give a concise form for the position of the first Bragg peak. We also extend the virial series previously suggested for disordered stealthy hyperuniform systems to higher dimensions in order to predict spatial decorrelation as a function of dimension. This prediction is then borne out by numerical simulations of disordered stealthy hyperuniform ground states in dimensions , which have only recently been made possible due to a highly parallelized algorithm.
先前的工作[Phys. Rev. X 5, 021020 (2015)]表明，隐身超均匀系统可被视为傅里叶空间的硬球，即在原点周围的球形区域中，结构因子恰好为零，这与现实空间硬球的对相关函数类似。早先的研究集中于空间维度 d=1-4，而在这里我们将分析扩展到更高的维度，以便与高维球体堆积和玻璃均场理论建立联系。我们利用这种对应关系证实了最致密的傅立叶空间硬球系统是布拉维晶格系统，而不是实空间硬球，后者的最致密构型被猜测为无序的。我们顺便给出了第一个布拉格峰位置的简明形式。我们还将之前提出的无序隐形超均匀系统的病毒序列扩展到更高维度，以预测空间不相关性是维度的函数。这一预测随后被维数为 d=2-8 的无序隐身超均匀基态的数值模拟所证实，由于采用了高度并行化的算法，这一模拟最近才得以实现。
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Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033257
Albert J. Pool, Alejandro D. Somoza, Conor Mc Keever, Michael Lubasch, Birger Horstmann
For the solution of time-dependent nonlinear differential equations, we present variational quantum algorithms (VQAs) that encode both space and time in qubit registers. The spacetime encoding enables us to obtain the entire time evolution from a single ground-state computation. We describe a general procedure to construct efficient quantum circuits for the cost function evaluation required by VQAs. To mitigate the barren plateau problem during the optimization, we propose an adaptive multigrid strategy. The approach is illustrated for the nonlinear Burgers equation. We classically optimize quantum circuits to represent the desired ground-state solutions, run them on IBM Q System One and Quantinuum System Model H1, and demonstrate that current quantum computers are capable of accurately reproducing the exact results.
为了求解随时间变化的非线性微分方程，我们提出了在量子位寄存器中同时对空间和时间进行编码的变分量子算法（VQAs）。时空编码使我们能够从一次地面状态计算中获得整个时间演化过程。我们描述了构建高效量子电路的一般程序，以实现 VQAs 所需的代价函数评估。为了缓解优化过程中的贫瘠高原问题，我们提出了一种自适应多网格策略。该方法针对非线性布尔格斯方程进行了说明。我们对量子电路进行了经典优化，以表示所需的基态解，并在 IBM Q System One 和 Quantinuum System Model H1 上运行这些电路，证明当前的量子计算机能够准确地再现精确结果。
{"title":"Nonlinear dynamics as a ground-state solution on quantum computers","authors":"Albert J. Pool, Alejandro D. Somoza, Conor Mc Keever, Michael Lubasch, Birger Horstmann","doi":"10.1103/physrevresearch.6.033257","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033257","url":null,"abstract":"For the solution of time-dependent nonlinear differential equations, we present variational quantum algorithms (VQAs) that encode both space and time in qubit registers. The spacetime encoding enables us to obtain the entire time evolution from a single ground-state computation. We describe a general procedure to construct efficient quantum circuits for the cost function evaluation required by VQAs. To mitigate the barren plateau problem during the optimization, we propose an adaptive multigrid strategy. The approach is illustrated for the nonlinear Burgers equation. We classically optimize quantum circuits to represent the desired ground-state solutions, run them on IBM Q System One and Quantinuum System Model H1, and demonstrate that current quantum computers are capable of accurately reproducing the exact results.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033256
Anying Feng, Jun Xu, Xiangming Hu
Spin squeezing has important applications in the field of quantum metrology and quantum information processing. Here we propose that coherent population trapping is well suitable for establishing cavity dissipation mechanism and generating a spin-squeezed state. An ensemble of double -type atoms is placed inside the two-mode optical cavity, where one subsystem is driven resonantly by two strong control fields to form a dark resonance and the other subsystem is coupled by two cavity vacuum fields and two external fields with large detunings. Due to the dark resonance, the atoms are trapped in a dark state and one has the maximal coherence between the two ground states. Two double off-resonance stimulated Raman scattering interactions are induced between fields and dressed atoms to establish a dissipative quantum dynamical process based on a collective cavity reservoir. As a result, strong stable spin squeezing is generated, which is verified by our numerical and analytical results.
自旋挤压在量子计量学和量子信息处理领域有着重要的应用。在这里，我们提出相干种群捕获非常适合建立腔耗散机制和产生自旋挤压态。一个由 N 个双Λ型原子组成的原子团被置于双模光腔内，其中一个Λ子系统由两个强控制场驱动形成暗共振，另一个Λ子系统由两个腔真空场和两个大调谐的外部场耦合。由于暗共振，原子被困在暗态中，其中一个原子在两个基态之间具有最大的相干性。场和被掺杂的原子之间会产生两个双关共振刺激拉曼散射相互作用，从而建立起一个基于集体腔库的耗散量子动力学过程。因此，产生了强烈稳定的自旋挤压，我们的数值和分析结果验证了这一点。
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Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033262
Charles Emmett Maher, Salvatore Torquato
Formulating order metrics that sensitively quantify the degree of order/disorder in many-particle systems in -dimensional Euclidean space across length scales is an outstanding challenge in physics, chemistry, and materials science. Since an infinite set of -particle correlation functions is required to fully characterize a system, one must settle for a reduced set of structural information, in practice. We initiate a program to use the local number variance associated with a spherical sampling window of radius (which encodes pair correlations) and an integral measure derived from it that depends on two specified radial distances and . Across the first three space dimensions (), we find these metrics can sensitively describe and categorize the degree of order/disorder of 41 different models of antihyperuniform, nonhyperuniform, disordered hyperuniform, and ordered hyperuniform many-particle systems at a specified length scale . Using our local variance metrics, we demonstrate the importance of assessing order/disorder with respect to a specific value of . These local order metrics could also aid in the inverse design of structures with prescribed length-scale-specific degrees of order/disorder that yield desired physical properties. In future work, it would be fruitful to explore the use of higher-order moments of the number of points within a spherical window of radius [S. Torquato et al., Phys. Rev. X11, 021028 (2021)] to devise even more sensitive order metrics.
在 d 维欧几里得空间 Rd 跨长度尺度上，制定能灵敏量化多粒子系统有序/无序程度的有序度量是物理学、化学和材料科学领域的一项突出挑战。由于要全面描述一个系统的特征，需要无穷多的 n 粒子相关函数集，因此在实践中，我们必须满足于结构信息集的减少。我们启动了一个程序，使用与半径为 R 的球形采样窗口相关的局部数量方差 σN2(R)（它编码了粒子对相关性），以及从它衍生出的积分量 ΣN(Ri,Rj)，它取决于两个指定的径向距离 Ri 和 Rj。在前三个空间维度（d=1,2,3）上，我们发现这些度量可以灵敏地描述和分类 41 种不同模型的有序/无序程度，包括指定长度尺度 R 下的反超均匀、非超均匀、无序超均匀和有序超均匀多粒子系统。利用我们的局部方差度量，我们证明了评估与特定 R 值相关的有序/无序的重要性。这些局部有序度量还有助于反向设计具有规定长度尺度特定有序/无序度的结构，从而产生所需的物理特性。在未来的工作中，探索使用半径为 R 的球窗内点数的高阶矩[S. Torquato 等人，Phys. Rev. X 11, 021028 (2021)]来设计更加灵敏的有序度量标准将是富有成效的。
{"title":"Local order metrics for many-particle systems across length scales","authors":"Charles Emmett Maher, Salvatore Torquato","doi":"10.1103/physrevresearch.6.033262","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033262","url":null,"abstract":"Formulating order metrics that sensitively quantify the degree of order/disorder in many-particle systems in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-dimensional Euclidean space <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi mathvariant=\"double-struck\">R</mi><mi>d</mi></msup></math> across length scales is an outstanding challenge in physics, chemistry, and materials science. Since an infinite set of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>n</mi></math>-particle correlation functions is required to fully characterize a system, one must settle for a reduced set of structural information, in practice. We initiate a program to use the local number variance <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msubsup><mi>σ</mi><mi>N</mi><mn>2</mn></msubsup><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math> associated with a spherical sampling window of radius <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>R</mi></math> (which encodes pair correlations) and an integral measure derived from it <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">Σ</mi><mi>N</mi></msub><mrow><mo>(</mo><msub><mi>R</mi><mi>i</mi></msub><mo>,</mo><msub><mi>R</mi><mi>j</mi></msub><mo>)</mo></mrow></mrow></math> that depends on two specified radial distances <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>R</mi><mi>i</mi></msub></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>R</mi><mi>j</mi></msub></math>. Across the first three space dimensions (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>d</mi><mo>=</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mn>3</mn></mrow></math>), we find these metrics can sensitively describe and categorize the degree of order/disorder of 41 different models of antihyperuniform, nonhyperuniform, disordered hyperuniform, and ordered hyperuniform many-particle systems at a specified length scale <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>R</mi></math>. Using our local variance metrics, we demonstrate the importance of assessing order/disorder with respect to a specific value of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>R</mi></math>. These local order metrics could also aid in the inverse design of structures with prescribed length-scale-specific degrees of order/disorder that yield desired physical properties. In future work, it would be fruitful to explore the use of higher-order moments of the number of points within a spherical window of radius <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>R</mi></mrow></math> [S. Torquato <i>et al.</i>, <span>Phys. Rev. X</span> <b>11</b>, 021028 (2021)] to devise even more sensitive order metrics.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.l032057
Eloy Piñol, Th. K. Mavrogordatos, Dustin Keys, Romain Veyron, Piotr Sierant, Miguel Angel García-March, Samuele Grandi, Morgan W. Mitchell, Jan Wehr, Maciej Lewenstein
The Gorini-Kossakowski-Sudarshan-Lindblad master equation (ME) governs the density matrix of open quantum systems (OQSs). When an OQS is subjected to weak continuous measurement, its state evolves as a stochastic quantum trajectory, whose statistical average solves the ME. The ensemble of such trajectories is termed an unraveling of the ME. We propose a method to operationally distinguish unravelings produced by the same ME in different measurement scenarios, using nonlinear averages of observables over trajectories. We apply the method to the paradigmatic quantum nonlinear system of resonance fluorescence in a two-level atom. We compare the Poisson-type unraveling, induced by direct detection of photons scattered from the two-level emitter, and the Wiener-type unraveling, induced by phase-sensitive detection of the emitted field. We show that a quantum-trajectory-averaged variance is able to distinguish these measurement scenarios. We evaluate the performance of the method, which can be readily extended to more complex OQSs, under a range of realistic experimental conditions.
戈里尼-科萨科夫斯基-苏达山-林德布拉德主方程（ME）控制着开放量子系统（OQS）的密度矩阵。当开放量子系统受到弱连续测量时，其状态会演变为随机量子轨迹，其统计平均值求解了主方程。这种轨迹的集合被称为 ME 的解蔽。我们提出了一种方法，利用轨迹上观测值的非线性平均值，从操作上区分不同测量情景下由相同 ME 产生的解译。我们将该方法应用于两级原子共振荧光的典型量子非线性系统。我们比较了由直接探测从两级发射器散射的光子而诱发的泊松型解开和由相敏探测发射场而诱发的维纳型解开。我们证明，量子轨迹平均方差能够区分这些测量情况。我们评估了该方法在一系列现实实验条件下的性能，该方法可随时扩展到更复杂的 OQS。
{"title":"Telling different unravelings apart via nonlinear quantum-trajectory averages","authors":"Eloy Piñol, Th. K. Mavrogordatos, Dustin Keys, Romain Veyron, Piotr Sierant, Miguel Angel García-March, Samuele Grandi, Morgan W. Mitchell, Jan Wehr, Maciej Lewenstein","doi":"10.1103/physrevresearch.6.l032057","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032057","url":null,"abstract":"The Gorini-Kossakowski-Sudarshan-Lindblad master equation (ME) governs the density matrix of open quantum systems (OQSs). When an OQS is subjected to weak continuous measurement, its state evolves as a stochastic quantum trajectory, whose statistical average solves the ME. The ensemble of such trajectories is termed an unraveling of the ME. We propose a method to operationally distinguish unravelings produced by the same ME in different measurement scenarios, using nonlinear averages of observables over trajectories. We apply the method to the paradigmatic quantum nonlinear system of resonance fluorescence in a two-level atom. We compare the Poisson-type unraveling, induced by direct detection of photons scattered from the two-level emitter, and the Wiener-type unraveling, induced by phase-sensitive detection of the emitted field. We show that a quantum-trajectory-averaged variance is able to distinguish these measurement scenarios. We evaluate the performance of the method, which can be readily extended to more complex OQSs, under a range of realistic experimental conditions.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033259
Ryo Watanabe, Hiroshi Ueda
Tensor network (TN) states, including entanglement renormalization (ER), can encompass a wider variety of entangled states. When the entanglement structure of the quantum state of interest is nonuniform in real space, accurately representing the state with a limited number of degrees of freedom hinges on appropriately configuring the TN to align with the entanglement pattern. However, a proposal has yet to show a structural search of ER due to its high computational cost and the lack of flexibility in its algorithm. In this study, we conducted an optimal structural search of TN, including ER, based on the reconstruction of their local structures with respect to variational energy. First, we demonstrated that our algorithm for the spin- tetramer singlets model could calculate exact ground energy using the multiscale entanglement renormalization ansatz (MERA) structure as an initial TN structure. Subsequently, we applied our algorithm to the random XY models with the two initial structures: MERA and the suitable structure underlying the strong disordered renormalization group. We found that, in both cases, our algorithm achieves improvements in variational energy, fidelity, and entanglement entropy. The degree of improvement in these quantities is superior in the latter case compared to the former, suggesting that utilizing an existing TN design method as a preprocessing step is important for maximizing our algorithm's performance.
{"title":"Automatic structural search of tensor network states including entanglement renormalization","authors":"Ryo Watanabe, Hiroshi Ueda","doi":"10.1103/physrevresearch.6.033259","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033259","url":null,"abstract":"Tensor network (TN) states, including entanglement renormalization (ER), can encompass a wider variety of entangled states. When the entanglement structure of the quantum state of interest is nonuniform in real space, accurately representing the state with a limited number of degrees of freedom hinges on appropriately configuring the TN to align with the entanglement pattern. However, a proposal has yet to show a structural search of ER due to its high computational cost and the lack of flexibility in its algorithm. In this study, we conducted an optimal structural search of TN, including ER, based on the reconstruction of their local structures with respect to variational energy. First, we demonstrated that our algorithm for the spin-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> tetramer singlets model could calculate exact ground energy using the multiscale entanglement renormalization ansatz (MERA) structure as an initial TN structure. Subsequently, we applied our algorithm to the random XY models with the two initial structures: MERA and the suitable structure underlying the strong disordered renormalization group. We found that, in both cases, our algorithm achieves improvements in variational energy, fidelity, and entanglement entropy. The degree of improvement in these quantities is superior in the latter case compared to the former, suggesting that utilizing an existing TN design method as a preprocessing step is important for maximizing our algorithm's performance.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We analyze a quantized pumping in a nonlinear non-Hermitian photonic system with nonadiabatic driving. The photonic system is made of a waveguide array, where the distances between adjacent waveguides are modulated. It is described by the Su-Schrieffer-Heeger model together with a saturated nonlinear gain term and a linear loss term. A topological interface state between the topological and the trivial phases is stabilized by the combination of a saturated nonlinear gain term and a linear loss term. We study the pumping of the topological interface state. We define the transfer-speed ratio by the ratio of the pumping speed of the center of mass of the wave packet to the driving speed of the topological interface. It is quantized topologically as in the adiabatic limit. It remains to be quantized dynamically unless the driving is not too fast even in the nonadiabatic regime. On the other hand, the wave packet collapses and there is no quantized pumping when the driving is too fast. In addition, the stability against disorder is more enhanced by stronger nonlinearity.
{"title":"Nonadiabatic nonlinear non-Hermitian quantized pumping","authors":"Motohiko Ezawa, Natsuko Ishida, Yasutomo Ota, Satoshi Iwamoto","doi":"10.1103/physrevresearch.6.033258","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033258","url":null,"abstract":"We analyze a quantized pumping in a nonlinear non-Hermitian photonic system with nonadiabatic driving. The photonic system is made of a waveguide array, where the distances between adjacent waveguides are modulated. It is described by the Su-Schrieffer-Heeger model together with a saturated nonlinear gain term and a linear loss term. A topological interface state between the topological and the trivial phases is stabilized by the combination of a saturated nonlinear gain term and a linear loss term. We study the pumping of the topological interface state. We define the transfer-speed ratio <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>ω</mi><mo>/</mo><mi mathvariant=\"normal\">Ω</mi></mrow></math> by the ratio of the pumping speed <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ω</mi></math> of the center of mass of the wave packet to the driving speed <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">Ω</mi></math> of the topological interface. It is quantized topologically as <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>ω</mi><mo>/</mo><mi mathvariant=\"normal\">Ω</mi><mo>=</mo><mn>1</mn></mrow></math> in the adiabatic limit. It remains to be quantized dynamically unless the driving is not too fast even in the nonadiabatic regime. On the other hand, the wave packet collapses and there is no quantized pumping when the driving is too fast. In addition, the stability against disorder is more enhanced by stronger nonlinearity.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.033263
Marlies Reher, Nicola A. Spaldin, Sophie F. Weber
We perform first-principles density functional calculations to elucidate structural, electronic, and magnetic properties at the interface of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers. This investigation is motivated by the fact that, despite the promise of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub><mo>−</mo><mi>Pt</mi></mrow></math> heterostructures in a variety of antiferromagnetic spintronic applications, many key structural, electronic, and magnetic properties at the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub><mo>−</mo><mi>Pt</mi></mrow></math> interface are poorly understood. We first analyze all inequivalent lateral interface alignments to determine the lowest energy interfacial structure. For all lateral alignments including the lowest energy one, we observe an accumulation of electrons at the interface between <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow></math> and Pt. We find an unexpected reversal of the magnetic moments of the interface Cr ions in the presence of Pt compared to surface Cr moments in vacuum-terminated <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow></mrow></math>. We also find that the heterostructure exhibits a magnetic proximity effect in the first three Pt layers at the interface with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow></math>, providing a mechanism by which the anomalous Hall effect can occur in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers. Our results provide the basis for a more nuanced interpretation of magnetotransport experiments on <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers and should inform future development of improved antiferromagnetic spintronic devices based on the <math xmlns="http://www.w3.org/1998/Math/Mat
{"title":"First-principles study of structural, electronic, and magnetic properties at the (0001)Cr2O3−(111)Pt interface","authors":"Marlies Reher, Nicola A. Spaldin, Sophie F. Weber","doi":"10.1103/physrevresearch.6.033263","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033263","url":null,"abstract":"We perform first-principles density functional calculations to elucidate structural, electronic, and magnetic properties at the interface of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers. This investigation is motivated by the fact that, despite the promise of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub><mo>−</mo><mi>Pt</mi></mrow></math> heterostructures in a variety of antiferromagnetic spintronic applications, many key structural, electronic, and magnetic properties at the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub><mo>−</mo><mi>Pt</mi></mrow></math> interface are poorly understood. We first analyze all inequivalent lateral interface alignments to determine the lowest energy interfacial structure. For all lateral alignments including the lowest energy one, we observe an accumulation of electrons at the interface between <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow></math> and Pt. We find an unexpected reversal of the magnetic moments of the interface Cr ions in the presence of Pt compared to surface Cr moments in vacuum-terminated <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow></mrow></math>. We also find that the heterostructure exhibits a magnetic proximity effect in the first three Pt layers at the interface with <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow></math>, providing a mechanism by which the anomalous Hall effect can occur in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers. Our results provide the basis for a more nuanced interpretation of magnetotransport experiments on <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mrow><mo>(</mo><mn>0001</mn><mo>)</mo></mrow><mrow><msub><mi>Cr</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>3</mn></msub></mrow><mo>−</mo><mrow><mo>(</mo><mn>111</mn><mo>)</mo></mrow><mi>Pt</mi></mrow></math> bilayers and should inform future development of improved antiferromagnetic spintronic devices based on the <math xmlns=\"http://www.w3.org/1998/Math/Mat","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1103/physrevresearch.6.l032056
Yuanjian Zheng, Michael A. Klatt, Hartmut Löwen
We show that dry scalar-order active field theories (AFTs) are universally hyperuniform, i.e., density fluctuations are anomalously suppressed in the long-time limit regardless of the integrability or functional form of the active contributions up to third order in gradient terms. These AFTs include active model B, active model , and effective Cahn-Hilliard models. Moreover, density variances and spectral densities are virtually indistinguishable from that of passive phase-separated hyperuniform fields. Higher moments of the density fluctuations, however, reveal activity-dependent higher-order correlations that are not captured by conventional two-point measures that characterize hyperuniformity.
{"title":"Universal hyperuniformity in active field theories","authors":"Yuanjian Zheng, Michael A. Klatt, Hartmut Löwen","doi":"10.1103/physrevresearch.6.l032056","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032056","url":null,"abstract":"We show that dry scalar-order active field theories (AFTs) are universally hyperuniform, i.e., density fluctuations are anomalously suppressed in the long-time limit regardless of the integrability or functional form of the active contributions up to third order in gradient terms. These AFTs include active model B, active model <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">B</mi><mo>+</mo></mrow></math>, and effective Cahn-Hilliard models. Moreover, density variances and spectral densities are virtually indistinguishable from that of passive phase-separated hyperuniform fields. Higher moments of the density fluctuations, however, reveal activity-dependent higher-order correlations that are not captured by conventional two-point measures that characterize hyperuniformity.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1103/physrevresearch.6.l032054
D. Sarenac, G. Gorbet, Charles W. Clark, D. G. Cory, H. Ekinci, M. E. Henderson, M. G. Huber, D. S. Hussey, C. Kapahi, P. A. Kienzle, Y. Kim, A. M. Long, J. D. Parker, T. Shinohara, F. Song, D. A. Pushin
Neutron interferometry has played a distinctive role in fundamental science and characterization of materials. Moiré neutron interferometers are candidate next-generation instruments: they offer microscopy-like magnification of the signal, enabling direct camera recording of interference patterns across the full neutron wavelength spectrum. Here we demonstrate the extension of phase-grating moiré interferometry to two-dimensional geometries. Our fork-dislocation phase gratings reveal phase singularities in the moiré pattern, and we explore orthogonal moiré patterns with two-dimensional phase gratings. Our measurements of phase topologies and gravitationally induced phase shifts are in good agreement with theory. These techniques can be implemented in existing neutron instruments to advance interferometric analyses of emerging materials and precision measurements of fundamental constants.
{"title":"Phase and contrast moiré signatures in two-dimensional cone beam interferometry","authors":"D. Sarenac, G. Gorbet, Charles W. Clark, D. G. Cory, H. Ekinci, M. E. Henderson, M. G. Huber, D. S. Hussey, C. Kapahi, P. A. Kienzle, Y. Kim, A. M. Long, J. D. Parker, T. Shinohara, F. Song, D. A. Pushin","doi":"10.1103/physrevresearch.6.l032054","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032054","url":null,"abstract":"Neutron interferometry has played a distinctive role in fundamental science and characterization of materials. Moiré neutron interferometers are candidate next-generation instruments: they offer microscopy-like magnification of the signal, enabling direct camera recording of interference patterns across the full neutron wavelength spectrum. Here we demonstrate the extension of phase-grating moiré interferometry to two-dimensional geometries. Our fork-dislocation phase gratings reveal phase singularities in the moiré pattern, and we explore orthogonal moiré patterns with two-dimensional phase gratings. Our measurements of phase topologies and gravitationally induced phase shifts are in good agreement with theory. These techniques can be implemented in existing neutron instruments to advance interferometric analyses of emerging materials and precision measurements of fundamental constants.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142211170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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