Physical Review X最新文献_第7页

Transition to Collective Motion in Nonreciprocal Active Matter: Coarse Graining Agent-Based Models into Fluctuating Hydrodynamics 非互易活性物质向集体运动的过渡：基于粗粒化主体的波动流体动力学模型

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-30 DOI: 10.1103/physrevx.15.041015

David Martin, Daniel Seara, Yael Avni, Michel Fruchart, Vincenzo Vitelli

Two hallmarks of nonequilibrium systems, from active colloids to animal herds, are agent motility and nonreciprocal interactions. Their interplay creates feedback loops that lead to complex spatiotemporal dynamics crucial to understand and control the nonlinear response of active systems. Here, we introduce a minimal model that captures these two features at the microscopic scale while admitting an exact hydrodynamic theory valid also in the fully nonlinear regime. Using statistical mechanics techniques, we exactly coarse-grain our nonreciprocal microscopic model into a fluctuating hydrodynamics and use dynamical systems insights to analyze the resulting equations. In the absence of motility, we find two transitions to oscillatory phases occurring via distinct mechanisms: a Hopf bifurcation and a saddle node on invariant circle bifurcation. In the presence of motility, this rigorous approach, complemented by numerical simulations, allows us to quantitatively assess the hitherto neglected impact of interspecies nonreciprocity on a paradigmatic transition in active matter: the emergence of collective motion. When nonreciprocity is weak, we show that flocking is accelerated and bands tend to synchronize with a spatial overlap controlled by nonlinearities. When nonreciprocity is strong, flocking is superseded by a chase and rest dynamical phase, where each species alternates between a chasing state, when they propagate, and a resting state, when they stand still. Phenomenological models with linear nonreciprocal couplings fail to predict the chase and rest phase, which illustrates the usefulness of our exact coarse-graining procedure. Finally, we demonstrate how fluctuations in finite systems can be harnessed to characterize microscopic nonreciprocity from macroscopic time-correlation functions, even in phases where nonreciprocal interactions do not affect the thermodynamic steady state.

从活跃的胶体到动物群，非平衡系统的两个标志是物质运动性和非互反相互作用。它们的相互作用产生反馈回路，导致复杂的时空动力学，这对于理解和控制主动系统的非线性响应至关重要。在这里，我们引入了一个最小模型，在微观尺度上捕捉这两个特征，同时承认在完全非线性状态下也有效的精确水动力理论。使用统计力学技术，我们精确地将我们的非互易微观模型粗粒度化为波动流体动力学，并使用动力系统的见解来分析所得方程。在没有运动的情况下，我们发现振荡相位的两个转变通过不同的机制发生：Hopf分岔和不变圆分岔上的鞍节点。在运动性存在的情况下，这种严谨的方法，辅以数值模拟，使我们能够定量地评估迄今为止被忽视的物种间非互易性对活跃物质范式转变的影响：集体运动的出现。当非互易性较弱时，我们的研究表明，在非线性控制的空间重叠下，群集加速，条带趋于同步。当非互易性很强时，群集被追逐和休息动态阶段所取代，在这个阶段，每个物种在追逐状态（繁殖时）和休息状态（静止时）之间交替。具有线性非互易耦合的现象学模型不能预测追逐和休息阶段，这说明了我们精确的粗粒度过程的有用性。最后，我们展示了如何利用有限系统的波动来表征宏观时间相关函数的微观非互易性，即使在非互易相互作用不影响热力学稳态的阶段。

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引用次数: 0

Clustering of Conditional Mutual Information and Quantum Markov Structure at Arbitrary Temperatures 任意温度下条件互信息聚类与量子马尔可夫结构

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-16 DOI: 10.1103/9hx7-pzxw

Tomotaka Kuwahara

Recent investigations have unveiled exotic quantum phases that elude characterization by simple bipartite correlation functions. In these phases, long-range entanglement arising from tripartite correlations plays a central role. Consequently, the study of multipartite correlations has become a focal point in modern physics. Here, conditional mutual information (CMI) is one of the most well-established information-theoretic measures, adept at encapsulating the essence of various exotic phases, including topologically ordered ones. Within the realm of quantum many-body physics, it has been a long-sought goal to establish a quantum analog to the Hammersley-Clifford theorem that bridges the two concepts of the Gibbs state and the Markov network. This theorem posits that the correlation length of CMI remains short-range across all thermal equilibrium quantum phases. In this work, we demonstrate that CMI exhibits exponential decay with respect to distance, with its correlation length increasing polynomially with respect to the inverse temperature. While this clustering theorem has previously been believed to hold for high temperatures devoid of thermal phase transitions, it has remained elusive at low temperatures, where genuine long-range entanglement is corroborated to exist by the quantum topological order. Our findings unveil that, even at low temperatures, a broad class of tripartite entanglement cannot manifest in the long-range regime. To achieve the proof, we establish a comprehensive formalism for analyzing the locality of effective Hamiltonians on subsystems, commonly known as the “entanglement Hamiltonian” or “Hamiltonian of mean force.” As one outcome of our analyses, we enhance the prior clustering theorem concerning bipartite entanglement. In essence, we investigate genuine bipartite entanglement that extends beyond the limitations of the positive-partial-transpose class.

最近的研究揭示了奇异的量子相，它们无法用简单的二部相关函数来表征。在这些阶段中，由三方相关引起的远程纠缠起着核心作用。因此，多方相关的研究已成为现代物理学的一个焦点。在这里，条件互信息（CMI）是最完善的信息论度量之一，它擅长于封装各种奇异相位的本质，包括拓扑有序的相位。在量子多体物理领域，建立一个类似汉默斯利-克利福德定理的量子模拟是一个长期追求的目标，该定理连接了吉布斯态和马尔可夫网络这两个概念。该定理假定CMI的相关长度在所有热平衡量子相中保持短范围。在这项工作中，我们证明了CMI相对于距离呈指数衰减，其相关长度相对于逆温度呈多项式增长。虽然这个聚类定理先前被认为适用于没有热相变的高温，但在低温下它仍然难以捉摸，在低温下，真正的远程纠缠被量子拓扑秩序证实存在。我们的发现揭示了，即使在低温下，大范围的三方纠缠也不能在长程状态下表现出来。为了实现证明，我们建立了一个综合的形式来分析子系统上有效哈密顿量的局部性，通常称为“纠缠哈密顿量”或“平均力哈密顿量”。作为我们分析的一个结果，我们改进了关于二部纠缠的先验聚类定理。实质上，我们研究了超越正偏转置类限制的真二部纠缠。

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引用次数: 0

Entangled Dual-Comb Spectroscopy 纠缠双梳光谱

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-15 DOI: 10.1103/plh2-cr8s

Abdulkarim Hariri, Shuai Liu, Haowei Shi, Quntao Zhuang, Xudong Fan, Zheshen Zhang

Optical frequency combs have emerged as a cornerstone for a wide range of areas, including spectroscopy, ranging, optical clocks, time and frequency transfer, waveform synthesis, and communications. However, quantum-mechanical fluctuations of the optical carrier impose fundamental performance limits on the precision of classical optical frequency combs, particularly in their use for interferometry and spectroscopy. Entanglement, as a quintessential quantum resource, allows for surpassing the fundamental limits of classical systems. Here, we introduce entanglement into the realm of optical frequency combs, formulating entangled dual-comb spectroscopy (EDCS) that surmounts the fundamental limits of classical DCS. EDCS capitalizes on tailored entangled structures across the frequency comb, enabling simultaneous detection of all comb lines below the standard quantum limit of classical DCS. Applying EDCS in gas detection, we achieve a 2.6-dB enhancement in signal-to-noise ratio and a 1.7-fold reduction in integration time over classical DCS, rendering EDCS particularly suited for dynamic chemical and biological sensing, where fast, precise measurements subject to power constraints are required. EDCS opens a new avenue for exploiting quantum frequency combs, underscoring their prospects in a plethora of applications in precision metrology, spectroscopy, and timekeeping.

光学频率梳已成为广泛领域的基石，包括光谱学，测距，光学时钟，时间和频率传输，波形合成和通信。然而，光学载流子的量子力学波动对经典光学频率梳的精度施加了基本的性能限制，特别是在干涉测量和光谱学中。纠缠作为一种典型的量子资源，允许超越经典系统的基本限制。在这里，我们将纠缠引入光学频率梳领域，制定了纠缠双梳光谱（EDCS），超越了经典DCS的基本限制。EDCS利用频率梳上定制的纠缠结构，能够同时检测低于经典DCS标准量子限制的所有梳线。将EDCS应用于气体检测，我们实现了2.6 db的信噪比增强，并将集成时间减少了1.7倍，使EDCS特别适合动态化学和生物传感，这些传感需要在功率限制下进行快速，精确的测量。EDCS为开发量子频率梳开辟了一条新的途径，强调了它们在精密计量、光谱学和计时领域的大量应用前景。

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引用次数: 0

Nonequilibrium Relaxation and Odd-Even Effect in Finite-Temperature Electron Gases 有限温度电子气体中的非平衡弛豫和奇偶效应

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-14 DOI: 10.1103/ly37-5gdw

Eric Nilsson, Ulf Gran, Johannes Hofmann

Pauli blocking in Fermi liquids imposes strong phase-space constraints on quasiparticle lifetimes, leading to a well-known quadratic-in-temperature decay rate of quasiparticle modes at low temperatures. In two-dimensional systems, however, even longer-lived modes are predicted (dubbed “odd-parity” modes) that involve a collective deformation of the Fermi distribution. Here, we present an efficient method to evaluate the full spectrum of relaxational eigenmodes of a Fermi liquid within kinetic theory. We employ this method to study the experimentally relevant case of a Fermi liquid with screened Coulomb interactions and map out the decay rates of quasiparticle modes beyond the asymptotic low-temperature limit up to the Fermi temperature, thus covering the entire temperature range of typical experiments. We confirm the existence of anomalously long-lived odd-parity modes and provide a comprehensive classification and detailed analysis of the relaxation spectrum. In particular, we find that (i) the odd-parity effect in the decay rates extends to temperatures as large as T=0.15TF, (ii) there is only a small number of long-lived odd-parity modes, with an infinite number of remaining modes that show standard Fermi-liquid scaling, and (iii) the ratio between the odd- and even-parity lifetimes is tunable with the Coulomb interaction strength, in addition to temperature, which reflects a difference in the microscopic relaxation mechanism of the modes. Our findings provide a comprehensive description of the nonequilibrium relaxation behavior of two-dimensional electron gases and bridge a significant gap in our understanding of these systems.

费米液体中的泡利阻塞对准粒子寿命施加了强烈的相空间约束，导致准粒子模式在低温下的二次衰减率。然而，在二维系统中，甚至可以预测更长寿的模式（称为“奇宇称”模式），这些模式涉及费米分布的集体变形。在这里，我们提出了一种在动力学理论中评估费米液体弛豫本征模全谱的有效方法。我们利用该方法研究了具有屏蔽库仑相互作用的费米液体的实验相关情况，并绘制了超过渐近低温极限直至费米温度的准粒子模式的衰减速率，从而覆盖了典型实验的整个温度范围。我们证实了异常长寿命奇宇称模式的存在，并提供了弛豫谱的全面分类和详细分析。特别地，我们发现(i)衰变率中的奇宇称效应延伸到T=0.15TF的温度，（ii）只有少数长寿命的奇宇称模式，其余无限数量的模式显示标准费米-液体标度，以及（iii）奇偶宇称寿命与库仑相互作用强度之间的比例是可调的，除了温度，这反映了模式的微观弛豫机制的差异。我们的发现提供了二维电子气体的非平衡弛豫行为的全面描述，并弥补了我们对这些系统的理解的重大差距。

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引用次数: 0

Experimental Demonstration of High-Fidelity Logical Magic States from Code Switching 码交换中高保真逻辑状态的实验演示

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-14 DOI: 10.1103/dck4-x9c2

Lucas Daguerre, Robin Blume-Kohout, Natalie C. Brown, David Hayes, Isaac H. Kim

Preparation of high-fidelity logical magic states has remained as a necessary but daunting step towards building a large-scale fault-tolerant quantum computer. One approach is to fault-tolerantly prepare a magic state in one code and then switch to another, a method known as code switching. We experimentally demonstrate this protocol on an ion-trap quantum processor, yielding a logical magic state encoded in an error-correcting code with state-of-the-art logical fidelity. Our experiment is based on the first demonstration of code switching between color codes, from the fifteen-qubit quantum Reed-Muller code to the seven-qubit Steane code. We prepare an encoded magic state in the Steane code with 82.58% probability, with an infidelity of at most 5.1(2.7)×10−4. The reported infidelity is lower than the leading infidelity of the physical operations utilized in the protocol by a factor of at least 2.7, indicating the quantum processor is below the pseudothreshold. Furthermore, we create two copies of the magic state in the same quantum processor and perform a logical Bell basis measurement for a sample-efficient certification of the encoded magic state. The high-fidelity magic state can be combined with the already-demonstrated fault-tolerant Clifford gates, state preparation, and measurement of the 2D color code, completing a universal set of fault-tolerant computational primitives with logical error rates equal or better than the physical two-qubit error rate.

准备高保真的逻辑魔法状态仍然是构建大规模容错量子计算机的必要但艰巨的一步。一种方法是在一段代码中容错地准备一个神奇状态，然后切换到另一段代码，这种方法称为代码切换。我们在离子阱量子处理器上实验证明了这种协议，产生了一个用最先进的逻辑保真度的纠错码编码的逻辑魔法状态。我们的实验是基于第一次在颜色代码之间进行代码切换的演示，从15量子位量子Reed-Muller代码到7量子位Steane代码。我们在Steane代码中准备了一个编码的魔法状态，概率为82.58%，不忠度不超过5.1（2.7）×10−4。报告的不忠比协议中使用的物理操作的主要不忠低至少2.7倍，表明量子处理器低于伪阈值。此外，我们在同一量子处理器中创建了魔法状态的两个副本，并执行逻辑贝尔基测量，以对编码的魔法状态进行采样效率认证。高保真神奇状态可以与已经演示的容错Clifford门、状态准备和2D色码的测量相结合，完成一组通用的容错计算原语，其逻辑错误率等于或优于物理双量子位错误率。

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引用次数: 0

Beyond Homes Scaling: Disorder, the Planckian Bound, and a New Universality 超越家园尺度：无序，普朗克界限，和一个新的普遍性

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-08 DOI: 10.1103/xbv7-3s3h

D. M. Broun, Vivek Mishra, J. S. Dodge, P. J. Hirschfeld

Beginning with high-Tc cuprate materials, it has been observed that many superconductors exhibit so-called “Homes scaling,” in which the zero-temperature superfluid density ρs0 is proportional to the product of the normal-state dc conductivity and the superconducting transition temperature σdcTc. For conventional, s-wave superconductors, such scaling has been shown to be a natural consequence of elastic-scattering disorder, not only in the extreme dirty limit, but across a broad range of scattering parameters. Here we show that when an analogous calculation is carried out for elastic scattering in d-wave superconductors, a stark contrast emerges, with ρs0∝(σdcTc)2 in the dirty limit, in apparent violation of Homes scaling. Within a simple approximate Migdal-Eliashberg treatment of inelastic scattering, we show how the observed Homes scaling is recovered. The normal-state behavior of near-optimally-doped cuprates is dominated by inelastic scattering, but significant deviations from Homes scaling occur for disorder-dominated cuprate systems, such as underdoped YBa2Cu3O6.333 and overdoped La2−xSrxCuO4, and in very clean materials with little inelastic scattering, such as Sr2

从高tc铜材料开始，人们观察到许多超导体表现出所谓的“家园尺度”，其中零温度超流体密度ρs0与正常状态直流电导率和超导转变温度σdcTc的乘积成正比。对于传统的s波超导体，这种缩放已经被证明是弹性散射无序的自然结果，不仅在极端脏极限，而且在广泛的散射参数范围内。这里我们表明，当对d波超导体中的弹性散射进行类似计算时，出现了鲜明的对比，ρ so0∝(σdcTc)2在脏极限中，明显违反了Homes标度。在非弹性散射的简单近似Migdal-Eliashberg处理中，我们展示了如何恢复观察到的Homes缩放。接近最佳掺杂的铜酸盐的正常状态行为是由非弹性散射主导的，但对于无序主导的铜酸盐体系，如欠掺杂的YBa2Cu3O6.333和过掺杂的La2−xSrxCuO4，以及非常干净的材料，如Sr2RuO4，非弹性散射很少，则会出现明显的偏离home标度。我们提出了一个修正的分析，其中原始Homes标度图的两个轴都由德鲁德等离子体质量ωp，D2归一化，并表明出现了一个新的通用标度，其中脏s波和脏d波超导体的超流体分数合并到一个点，在这个点上，普朗克边界上发生了正常状态散射。综合结果为超导体的序参量对称性、散射强度和特性分类提供了一种新的工具。虽然我们的模型是从费米液体假设开始的，但它对未掺杂铜酸盐的描述却出奇地好。

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引用次数: 0

Experimental Signatures of a New Channel of the Deuteron-Deuteron Reaction at Very Low Energy 极低能量氘核-氘核反应新通道的实验特征

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-07 DOI: 10.1103/chlp-b215

R. Dubey, K. Czerski, Gokul Das H., A. Kowalska, N. Targosz-Sleczka, M. Kaczmarski, M. Valat

The discovery of a new, e+e− reaction channel in deuteron-deuteron (DD) fusion at very low energies might have major implications for understanding primordial and stellar nucleosynthesis, where electron-positron reaction channels are typically not considered. It could also enable research on metal hydride fusion, potentially paving the way for the design and construction of next-generation fusion energy sources. Following the first experimental indications of electron emission, we present here an extensive experimental study confirming emission of high-energy electrons from DD reaction at very low energy. A simultaneous use of Si charged particle detectors of different thicknesses and large-volume NaI(Tl) and HPGe detectors has allowed the determination of the branching ratios between emitted protons, neutrons, and e+e− pairs for deuteron energies down to 5 keV. The high-energy positrons could be unambiguously detected by their bremsstrahlung spectra and annihilation radiation, supported by the eant4 Monte Carlo simulations. The theoretical calculations, based on a destructive interference between the threshold resonance and the known broad resonance in He4, agree very well with experimentally observed increase of branching ratios for lowering projectile energies. The partial width of the threshold resonance for the internal e+e− pair creation should be at least 10 times larger than that of the proton channel.

在极低能量的氘核-氘核（DD）聚变中发现了一个新的e+e−反应通道，这可能对理解原始和恒星核合成具有重大意义，在这些地方通常不考虑电子-正电子反应通道。它还可以促进金属氢化物聚变的研究，为下一代聚变能源的设计和建造铺平道路。继电子发射的第一个实验指示之后，我们在这里提出了一个广泛的实验研究，证实了DD反应在非常低的能量下发射高能电子。同时使用不同厚度的Si带电粒子探测器和大体积的NaI（Tl）和HPGe探测器，可以确定氘核能量低至5 keV时发射的质子、中子和e+e -对之间的分支比。高能正电子可以通过它们的轫致辐射光谱和湮灭辐射明确地探测到，并得到了eant4蒙特卡罗模拟的支持。理论计算基于He4中阈值共振和已知宽共振之间的破坏性干涉，与实验观察到的分支比的增加对降低弹射能量的影响非常吻合。内部e+e−对产生的阈值共振的部分宽度应至少大于质子通道的10倍。

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引用次数: 0

Heralded Entanglement of On-Demand Spin-Wave Solid-State Quantum Memories for Multiplexed Quantum Network Links 多路量子网络链路中按需自旋波固态量子存储器的预示纠缠

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-03 DOI: 10.1103/wvv1-6lg8

Jonathan Hänni, Alberto E. Rodríguez-Moldes, Félicien Appas, Soeren Wengerowsky, Dario Lago-Rivera, Markus Teller, Samuele Grandi, Hugues de Riedmatten

The ability to distribute heralded entanglement between distant matter nodes is a primitive for the implementation of large-scale quantum networks. Some of the most crucial requirements for future applications include high heralding rates at telecom wavelengths, multiplexed operation, and on-demand retrieval of stored excitations for synchronization of separate quantum links. Despite tremendous progress in various physical systems, the demonstration of telecom-heralded entanglement between quantum nodes featuring both multiplexed operation and on-demand retrieval remains elusive. In this work, we combine narrow band parametric photon-pair sources and solid-state quantum memories based on rare-earth doped crystals to demonstrate telecom-heralded entanglement between spatially separated spin-wave quantum memories with fully adjustable recall time and temporal multiplexing of 15 modes. In a first experiment, the storage in the spin state is conditioned on the entanglement heralding. We take advantage of the control over readout pulse phase to achieve feedforward conditional phase shifts on the stored photons depending on which heralding detector clicked. We exploit this effect to double the entanglement heralding rate for a given quantum state up to 510counts/s, with an associated detection rate of 0.32 counts/s and measured positive concurrence by up to 6 standard deviations. In a second experiment, we simulate the communication time of a long-distance link by implementing an unconditional storage scheme with a dead time of 100 μs. We take advantage of temporal multiplexing to increase the entanglement rates by a factor of 15 with respect to single mode storage, reaching a value of 22 counts/s per heralding detector. These results establish our architecture as a prime candidate for the implementation of scalable high-rate quantum network links.

在遥远的物质节点之间分布预示纠缠的能力是实现大规模量子网络的基本条件。未来应用的一些最关键的要求包括电信波长的高预告率，多路复用操作，以及为同步单独的量子链路而按需检索存储的激发。尽管在各种物理系统中取得了巨大的进步，但电信预示的量子节点之间的纠缠，具有多路复用操作和按需检索的演示仍然难以捉摸。在这项工作中，我们结合了窄带参数光子对源和基于稀土掺杂晶体的固态量子存储器，以证明具有完全可调回忆时间和15种模式的时间复用的空间分离自旋波量子存储器之间的电信预示纠缠。在第一个实验中，自旋态的存储以纠缠预示为条件。我们利用对读出脉冲相位的控制来实现存储光子的前馈条件相移，这取决于哪个预示探测器点击。我们利用这一效应将给定量子态的纠缠预示率提高了一倍，达到510counts/s，相关检测率为0.32 counts/s，并测量了高达6个标准差的正并发性。在第二个实验中，我们通过实现死区时间为100 μs的无条件存储方案来模拟远程链路的通信时间。我们利用时间复用将纠缠率提高到单模存储的15倍，达到每个预警检测器22个计数/秒的值。这些结果使我们的架构成为实现可扩展的高速量子网络链路的主要候选者。

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引用次数: 0

Sensing and Control of Single Trapped Electrons above 1 K 1k以上单捕获电子的传感与控制

IF 12.5 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-02 DOI: 10.1103/vcl7-73ms

K. E. Castoria, N. R. Beysengulov, G. Koolstra, H. Byeon, E. O. Glen, M. Sammon, S. A. Lyon, J. Pollanen, D. G. Rees

Electrons trapped on the surface of cryogenic substrates (liquid helium, solid neon, or hydrogen) are an emerging platform for quantum information processing made attractive by the inherent purity of the electron environment, the scalability of trapping devices, and the predicted long lifetime of electron spin states. Here we demonstrate the spatial control and detection of single electrons above the surface of liquid helium at temperatures above 1 K. A superconducting coplanar waveguide resonator is used to read out the charge state of an electron trap defined by gate electrodes beneath the helium surface. Dispersive frequency shifts are observed as the trap is loaded with electrons, from several tens down to single electrons. These frequency shifts are in good agreement with our theoretical model that treats each electron as a classical oscillator coupled to the cavity field. This sensitive charge readout scheme can aid efforts to develop large-scale quantum processors that require the high cooling powers available in cryostats operating above 1 K.

捕获在低温底物（液氦、固体氖或氢）表面的电子是量子信息处理的新兴平台，由于电子环境的固有纯度、捕获设备的可扩展性以及电子自旋态的预期长寿命而具有吸引力。在这里，我们展示了液氦表面以上的单电子在1 K以上温度下的空间控制和探测。利用超导共面波导谐振器读出氦表面下由栅极电极定义的电子阱的电荷状态。当阱中装载电子时，可以观察到色散频移，从几十个电子到单个电子。这些频移很好地符合我们的理论模型，将每个电子视为耦合到腔场的经典振荡器。这种灵敏的电荷读出方案可以帮助开发大规模量子处理器，这些处理器需要在工作在1k以上的低温恒温器中提供高冷却功率。

引用次数: 0

Connectivity Structure and Dynamics of Nonlinear Recurrent Neural Networks. 非线性递归神经网络的连通性结构与动力学。

IF 15.7 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X

Pub Date : 2025-10-01 Epub Date: 2025-11-03 DOI: 10.1103/2jt7-c8cq

David G Clark, Owen Marschall, Alexander van Meegen, Ashok Litwin-Kumar

Studies of the dynamics of nonlinear recurrent neural networks often assume independent and identically distributed couplings, but large-scale connectomics data indicate that biological neural circuits exhibit markedly different connectivity properties. These include rapidly decaying singular-value spectra and structured singular-vector overlaps. Here, we develop a theory to analyze how these forms of structure shape high-dimensional collective activity in nonlinear recurrent neural networks. We first introduce the random-mode model, a random-matrix ensemble related to the singular-value decomposition that enables control over the spectrum and right-left mode overlaps. Then, using a novel path-integral calculation, we derive analytical expressions that reveal how connectivity structure affects features of collective dynamics: the dimension of activity, which quantifies the number of high-variance collective-activity fluctuations, and the temporal correlations that characterize the timescales of these fluctuations. We show that connectivity structure can be invisible in single-neuron activities while dramatically shaping collective activity. Furthermore, despite the nonlinear, high-dimensional nature of these networks, the dimension of activity depends on just two connectivity parameters-the variance of the couplings and the effective rank of the coupling matrix, which quantifies the number of dominant rank-one connectivity components. We contrast the effects of single-neuron heterogeneity and low dimensional connectivity, making predictions about how z-scoring data affects the dimension of activity. Finally, we demonstrate the presence of structured overlaps between left and right modes in the Drosophila connectome, incorporate them into the theory, and show how they further shape collective dynamics.

非线性递归神经网络的动力学研究通常假设独立和同分布的耦合，但大规模的连接组学数据表明，生物神经回路表现出明显不同的连接特性。这包括快速衰减的奇异值光谱和结构化的奇异向量重叠。在这里，我们发展了一个理论来分析这些形式的结构如何在非线性递归神经网络中塑造高维集体活动。我们首先介绍随机模式模型，这是一种与奇异值分解相关的随机矩阵集成，可以控制频谱和左右模式重叠。然后，使用一种新颖的路径积分计算，我们得出了揭示连通性结构如何影响集体动态特征的解析表达式：活动维度，量化了高方差集体活动波动的数量，以及表征这些波动的时间尺度的时间相关性。我们表明，连接结构在单个神经元活动中是不可见的，而在极大地影响集体活动。此外，尽管这些网络具有非线性、高维的性质，但活动的维度仅取决于两个连接参数——耦合的方差和耦合矩阵的有效秩，后者量化了排名第一的主要连接组件的数量。我们对比了单神经元异质性和低维连通性的影响，预测了z评分数据如何影响活动的维度。最后，我们证明了果蝇连接体中左右模式之间存在结构性重叠，并将其纳入理论，并展示了它们如何进一步塑造集体动力学。

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引用次数: 0

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