Physical Review最新文献_第2页

Reconfigurable neural spiking in bias field free spin Hall nano-oscillator 偏置场自由自旋霍尔纳米振荡器中的可重构神经尖峰

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physrevb.108.184411

Sourabh Manna, Rohit Medwal, Rajdeep Singh Rawat

{"title":"Reconfigurable neural spiking in bias field free spin Hall nano-oscillator","authors":"Sourabh Manna, Rohit Medwal, Rajdeep Singh Rawat","doi":"10.1103/physrevb.108.184411","DOIUrl":"https://doi.org/10.1103/physrevb.108.184411","url":null,"abstract":"In this paper, we theoretically investigate neuronlike spiking dynamics in an elliptic ferromagnet (FM)/heavy metal bilayer-based spin Hall nano-oscillator (SHNO) in a bias field free condition, very suitable for practical realization of brain-inspired computing schemes. We demonstrate regular periodic spiking with tunable frequency as well as the leaky integrate-and-fire (LIF) behavior in a single SHNO by manipulating the pulse features of input current. The frequency of regular periodic spiking is tunable in a range of 0.5--0.96 GHz (460 MHz bandwidth) through adjusting the magnitude of constant input DC current density. We further demonstrate the reconfigurability of spiking dynamics in response to a time-varying input accomplished by continuously increasing the input current density as a linear function of time. Macrospin theory and micromagnetic simulation provide insight into the origin of bias field free auto-oscillation and the spiking phenomena in our SHNO. In addition, we discuss how the shape anisotropy of the elliptic FM influence the bias field free auto-oscillation characteristics, including threshold current, frequency, and transition from in-plane to out-of-plane precession. The SHNO operates $<{10}^{12}phantom{rule{0.16em}{0ex}}mathrm{A}/{mathrm{m}}^{2}$ input current density and exhibits a large auto-oscillation amplitude, ensuring high output power. We show that the threshold current density can be reduced by decreasing the ellipticity of the FM layer as well as enhancing the perpendicular magnetic anisotropy. These findings highlight the potential of bias field free elliptic SHNO in designing power-efficient spiking neuron-based neuromorphic hardware.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"41 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134900662","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}

引用次数: 0

Epistasis and pleiotropy shape biophysical protein subspaces associated with drug resistance 上位性和多效性形成与耐药相关的生物物理蛋白亚空间

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreve.108.054408

C. Brandon Ogbunugafor, Rafael F. Guerrero, Miles D. Miller-Dickson, Eugene I. Shakhnovich, Matthew D. Shoulders

{"title":"Epistasis and pleiotropy shape biophysical protein subspaces associated with drug resistance","authors":"C. Brandon Ogbunugafor, Rafael F. Guerrero, Miles D. Miller-Dickson, Eugene I. Shakhnovich, Matthew D. Shoulders","doi":"10.1103/physreve.108.054408","DOIUrl":"https://doi.org/10.1103/physreve.108.054408","url":null,"abstract":"Protein space is a rich analogy for genotype-phenotype maps, where amino acid sequence is organized into a high-dimensional space that highlights the connectivity between protein variants. It is a useful abstraction for understanding the process of evolution, and for efforts to engineer proteins towards desirable phenotypes. Few mentions of protein space consider how protein phenotypes can be described in terms of their biophysical components, nor do they rigorously interrogate how forces like epistasis---describing the nonlinear interaction between mutations and their phenotypic consequences---manifest across these components. In this study, we deconstruct a low-dimensional protein space of a bacterial enzyme (dihydrofolate reductase; DHFR) into ``subspaces'' corresponding to a set of kinetic and thermodynamic traits [${k}_{mathrm{cat}}, {K}_{M}, {K}_{i}$, and ${T}_{m}$ (melting temperature)]. We then examine how combinations of three mutations (eight alleles in total) display pleiotropy, or unique effects on individual subspace traits. We examine protein spaces across three orthologous DHFR enzymes (Escherichia coli, Listeria grayi, and Chlamydia muridarum), adding a genotypic context dimension through which epistasis occurs across subspaces. In doing so, we reveal that protein space is a deceptively complex notion, and that future applications to bioengineering should consider how interactions between amino acid substitutions manifest across different phenotypic subspaces.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"42 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134900655","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}

引用次数: 0

Enhanced chiral edge currents and orbital magnetic moment in chiral d -wave superconductors from mesoscopic finite-size effects 介观有限尺寸效应下手性d波超导体中增强的手性边缘电流和轨道磁矩

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physrevb.108.174505

P. Holmvall, A. M. Black-Schaffer

{"title":"Enhanced chiral edge currents and orbital magnetic moment in chiral d -wave superconductors from mesoscopic finite-size effects","authors":"P. Holmvall, A. M. Black-Schaffer","doi":"10.1103/physrevb.108.174505","DOIUrl":"https://doi.org/10.1103/physrevb.108.174505","url":null,"abstract":"Chiral superconductors spontaneously break time-reversal symmetry and host topologically protected edge modes, supposedly generating chiral edge currents which are typically taken as a characteristic fingerprint of chiral superconductivity. However, recent studies have shown that the total edge current in two dimensions (2D) often vanishes for all chiral superconductors except for chiral $p$-wave, especially at low temperatures, thus severely impeding potential experimental verification and characterization of these superconductors. In this work, we use the quasiclassical theory of superconductivity to study mesoscopic disk-schaped chiral $d$-wave superconductors. We find that mesoscopic finite-size effects cause a dramatic enhancement of the total charge current and orbital magnetic moment (OMM), even at low temperatures. We study how these quantities scale with temperature, spontaneous Meissner screening, and system radius $mathcal{R}ensuremath{in}[5,200]{ensuremath{xi}}_{0}$ with superconducting coherence length ${ensuremath{xi}}_{0}$. We find a general $1/mathcal{R}$ scaling in the total charge current and OMM for sufficiently large systems, but this breaks down in small systems, instead producing a local maximum at $mathcal{R}ensuremath{approx}10--20{ensuremath{xi}}_{0}$ due to mesoscopic finite-size effects. These effects also cause a spontaneous charge-current reversal opposite to the chirality below $mathcal{R}<10{ensuremath{xi}}_{0}$. Our work highlights mesoscopic systems as a route to experimentally verify chiral $d$-wave superconductivity, measurable with magnetometry.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"36 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134954094","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}

引用次数: 0

Extended states in one-dimensional aperiodic lattices with linearly varying patches 具有线性变化斑块的一维非周期格中的扩展态

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physrevb.108.184201

Longyan Gong

引用次数: 0

Effective mass and interaction energy of heavy Bose polarons at unitarity 重玻色极化子的有效质量和相互作用能

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreva.108.l051301

Nikolay Yegovtsev, Victor Gurarie

引用次数: 2

Enhanced optomechanical interaction in an unbalanced Michelson-Sagnac interferometer 非平衡Michelson-Sagnac干涉仪中增强的光-力相互作用

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreva.108.053507

Alexandr Karpenko, Mikhail Korobko, Sergey P. Vyatchanin

{"title":"Enhanced optomechanical interaction in an unbalanced Michelson-Sagnac interferometer","authors":"Alexandr Karpenko, Mikhail Korobko, Sergey P. Vyatchanin","doi":"10.1103/physreva.108.053507","DOIUrl":"https://doi.org/10.1103/physreva.108.053507","url":null,"abstract":"Quantum optomechanical systems enable the study of fundamental questions on the quantum nature of massive objects. For that a strong coupling between light and mechanical motion is required, which presents a challenge for massive objects. In particular, large interferometric sensors with low-frequency oscillators are difficult to bring into the quantum regime. Here we propose unbalancing the central beam splitter in the Michelson-Sagnac interferometer, which allows us to boost the optomechanical coupling strength compared with a balanced beam splitter. This unbalancing allows us to enhance the cooperative action of two types of optomechanical coupling present in the system: dissipative and dispersive. We analyze two different configurations, in which the optomechanical cavity is formed by the mirror for the laser pump field (power recycling) and by the mirror for the signal field (signal recycling). We show that the imbalance of the beam splitter allows us to dramatically increase the optical cooling of the test-mass motion. We also formulate the conditions for observing quantum radiation-pressure noise and ponderomotive squeezing. Our configuration could serve as the basis for more complex modifications of the interferometer that would utilize the enhanced coupling strength. This would allow us to efficiently reach the quantum state of large test masses, opening the way to studying the fundamental aspects of quantum mechanics and the experimental search for quantum gravity.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"34 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134901349","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}

引用次数: 0

Bottom-up approach to room-temperature quantum systems 室温量子系统的自底向上方法

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreva.108.053710

Bochao Wei, Chao Li, Ce Pei, Chandra Raman

引用次数: 0

Soliton approximation in continuum models of leader-follower behavior 领导-追随者行为连续模型中的孤子近似

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreve.108.054407

F. Terragni, W. D. Martinson, M. Carretero, P. K. Maini, L. L. Bonilla

{"title":"Soliton approximation in continuum models of leader-follower behavior","authors":"F. Terragni, W. D. Martinson, M. Carretero, P. K. Maini, L. L. Bonilla","doi":"10.1103/physreve.108.054407","DOIUrl":"https://doi.org/10.1103/physreve.108.054407","url":null,"abstract":"Complex biological processes involve collective behavior of entities (bacteria, cells, animals) over many length and time scales and can be described by discrete models that track individuals or by continuum models involving densities and fields. We consider hybrid stochastic agent-based models of branching morphogenesis and angiogenesis (new blood vessel creation from preexisting vasculature), which treat cells as individuals that are guided by underlying continuous chemical and/or mechanical fields. In these descriptions, leader (tip) cells emerge from existing branches and follower (stalk) cells build the new sprout in their wake. Vessel branching and fusion (anastomosis) occur as a result of tip and stalk cell dynamics. Coarse graining these hybrid models in appropriate limits produces continuum partial differential equations (PDEs) for endothelial cell densities that are more analytically tractable. While these models differ in nonlinearity, they produce similar equations at leading order when chemotaxis is dominant. We analyze this leading order system in a simple quasi-one-dimensional geometry and show that the numerical solution of the leading order PDE is well described by a soliton wave that evolves from vessel to source. This wave is an attractor for intermediate times until it arrives at the hypoxic region releasing the growth factor. The mathematical techniques used here thus identify common features of discrete and continuum approaches and provide insight into general biological mechanisms governing their collective dynamics.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"13 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134991293","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}

引用次数: 0

Nonequilibrium steady states in coupled asymmetric and symmetric exclusion processes 耦合不对称和对称不相容过程中的非平衡态

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreve.108.054122

Atri Goswami, Utsa Dey, Sudip Mukherjee

{"title":"Nonequilibrium steady states in coupled asymmetric and symmetric exclusion processes","authors":"Atri Goswami, Utsa Dey, Sudip Mukherjee","doi":"10.1103/physreve.108.054122","DOIUrl":"https://doi.org/10.1103/physreve.108.054122","url":null,"abstract":"We propose and study a one-dimensional (1D) model consisting of two lanes with open boundaries. One of the lanes executes diffusive and the other lane driven unidirectional or asymmetric exclusion dynamics, which are mutually coupled through particle exchanges in the bulk. We elucidate the generic nonuniform steady states in this model. We show that in a parameter regime, where hopping along the TASEP lane, diffusion along the SEP lane, and the exchange of particles between the TASEP and SEP lanes compete, the SEP diffusivity $D$ appears as a tuning parameter for both the SEP and TASEP densities for a given exchange rate in the nonequilibrium steady states of this model. Indeed, $D$ can be tuned to achieve phase coexistence in the asymmetric exclusion dynamics together with spatially smoothly varying density in the diffusive dynamics in the steady state. We obtain phase diagrams of the model using mean field theories, and corroborate and complement the results with stochastic Monte Carlo simulations. This model reduces to an isolated open totally asymmetric exclusion process (TASEP) and an open TASEP with bulk particle nonconserving Langmuir kinetics (LK), respectively, in the limits of vanishing and diverging particle diffusivity in the lane executing diffusive dynamics. Thus, this model works as an overarching general model, connecting both pure TASEPs and TASEPs with LK in different asymptotic limits. We further define phases in the SEP and obtain phase diagrams and show their correspondence with the TASEP phases. In addition to its significance as a 1D driven, diffusive model, this model also serves as a simple reduced model for cell biological transport by molecular motors undergoing diffusive and directed motion inside eukaryotic cells.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":"42 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134900656","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}

引用次数: 0

Generalized dynamical theories in phase space and the hydrogen atom 相空间与氢原子的广义动力学理论

Physical Review Pub Date : 2023-11-14 DOI: 10.1103/physreva.108.052212

Martin Plávala, Matthias Kleinmann

引用次数: 2