Topology is an important determinant of the behavior of a great number of condensed-matter systems, but until recently it has played a minor role in elasticity. We develop a theory for the deformations of a class of twisted non-Euclidean sheets, which have a symmetry based on the celebrated Bonnet isometry. We show that nonorientability is an obstruction to realizing the symmetry globally, and it induces a geometric phase that captures a memory analogous to a previously identified one in 2D metamaterials. However, we show that orientable ribbons can also obstruct realizing the symmetry globally. This new obstruction is mediated by how the unit normal vector winds around the centerline of the ribbon and provides conditions for constructing soft modes of deformation compatible with the topology of multiply twisted connected ribbons.

Several excitable systems, such as the heart, self-organize into complex spatiotemporal patterns that involve wave collisions and rotating vortices. The dynamics between these structures are incompletely understood. Here we establish a comprehensive topological framework in three spatial dimensions. Conduction blocks are identified as phase defect surfaces, on which three types of closed curves move and carry a topological vector charge. Our framework not only sheds new light on twistons and hybrid reentry but also predicts new states: a Möbius scroll wave and conduction block surfaces that can split, branch, or contain multiple filaments. We hypothesize that the latter play a role in cardiac arrhythmias.

Active movement is essential for the survival of microorganisms like bacteria, algae, and unicellular parasites. In three dimensions, both swimming and gliding microorganisms often exhibit helical trajectories. One such case are malaria parasites gliding through 3D hydrogels, for which we find that the internal correlation time for the stochastic process generating propulsion is similar to the time taken for one helical turn. Motivated by this experimental finding, here we theoretically analyze the case of finite internal correlation time for microorganisms with helical trajectories as chiral active particles with an Ornstein-Uhlenbeck process for torque. We present an analytical solution which is in very good agreement with computer simulations. We then show that, for this type of internal noise, chirality and rotation increase the persistence of motion and results in helical trajectories that have a larger long-time mean squared displacement than straight trajectories at the same propulsion speed. Finally, we provide experimental evidence for this prediction for the case of malaria parasites.

We report on the realization of an efficient solid-state spin-wave quantum memory, with on-demand readout, using the full atomic frequency comb (AFC) scheme in a ${\mathrm{Pr}}^{3+}:{\mathrm{Y}}_2{\mathrm{SiO}}_5$ crystal embedded in an impedance-matched cavity. We demonstrate operation at the single-photon level by storing weak coherent states with an efficiency up to $(40\pm 2)\%$ and a signal-to-noise ratio of 14 for an input photon number of 0.42 photons per pulse. We also investigated the enhancement of the incoherent noise due to the impedance-matched cavity and characterized the quantum memory performance, showing a two-way transfer from excited to spin states and back of up to 83%. Finally, we confirmed the quantum nature of our memory by storing nonclassical states of light, i.e., a heralded single photon from a nondegenerate spontaneous parametric down-conversion source, and achieved nonclassical correlations between the heralding and the stored-and-retrieved photon. These results demonstrate that impedance-matched AFC spin-wave quantum memories with on-demand readout can be used for experiments involving the storage of photonic quantum states. They also open the door to solid-state on-demand quantum memories with very high efficiencies, serving as a key resource for quantum networks and quantum repeaters.

Entanglement has the ability to enhance the transmission of classical information over a quantum channel. However, fully harvesting this advantage typically requires complex entangling measurements, which are challenging to implement and scale with the system’s size. In this Letter, we consider a natural quantum information primitive known as a random access code in which the message to be communicated is selected stochastically. We introduce a protocol that leverages high-dimensional entanglement to perform this task perfectly, without requiring quantum interference between particles at the measurement station. We experimentally demonstrate how this unlocks implementation in the high-dimensional regime through an optical setup using eight-dimensional entanglement and multioutcome detection, providing a practical solution for stochastic communication and a robust method for certifying the dimensionality of entanglement in communication experiments.

We report a study of the hadronic transitions ${\chi }_{bJ}(2P)\to \omega \mathrm{\Upsilon }(1S)$, with $\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0$, using $28.2\times {10}^6\mathrm{\Upsilon }(3S)$ mesons recorded by the Belle detector. We present the first evidence for the near-threshold transition ${\chi }_{b0}(2P)\to \omega \mathrm{\Upsilon }(1S)$, the analog of the near-threshold charm sector decay ${\chi }_{c1}(3872)\to \omega J/\psi$, with a branching fraction of $\mathcal{B}({\chi }_{b0}(2P)\to \omega \mathrm{\Upsilon }(1S))=(0.55\pm 0.19\pm 0.07)\%$. We also obtain branching fractions of $\mathcal{B}({\chi }_{b1}(2P)\to \omega \mathrm{\Upsilon }(1S))=({2.39}_{-0.19}^{+0.20}\pm 0.24)\%$ and $\mathcal{B}({\chi }_{b2}(2P)\to \omega \mathrm{\Upsilon }(1S))=({0.47}_{-0.12}^{+0.13}\pm 0.06)\%$, confirming the measurement of the $\omega$ transitions of the $J=1,2P$–wave states. The ratio for the $J=2$ to $J=1$ transitions is also measured and found to differ by 3.3 standard deviations from the expected value in the QCD multipole expansion.

Understanding the mechanism of high-temperature superconductivity is among the most important problems in physics, one for which quantum simulation can provide new insights. However, it remains challenging to characterize superconductivity in existing cold-atom quantum simulation platforms. Here, we introduce a protocol for measuring a broad class of observables in fermionic quantum gas microscopes, including long-range superconducting pairing correlations (after a repulsive-to-attractive mapping). The protocol only requires global controls followed by site-resolved particle number measurements—capabilities that have been already demonstrated in multiple experiments—and is designed by analyzing the Hilbert space of fermions on two sites. The protocol is sample-efficient and we further optimize our pulses for robustness to experimental imperfections such as lattice inhomogeneity. Our Letter introduces a general tool for manipulating quantum states on optical lattices, enhancing their ability to tackle problems such as high-temperature superconductivity.

We apply a recently developed theory of the nonphononic vibrational density of states (DOS) in glasses to investigate the impact of local frozen-in stresses on the low-temperature specific heat. Using a completely harmonic description we show that the hybridization of the local nonphononic vibrational excitations with the waves leads to a low-frequency DOS, in excess to the Debye one, which varies linearly with frequency up to a certain crossover frequency, and then becomes constant. The actual value of the crossover depends of the ratio between the local stresses and the shear modulus. This excess DOS leads to a low-temperature specific heat with an apparent temperature exponent, which is between one and two, as observed experimentally. We discuss how these findings may be utilized for the characterization of glassy materials. We further compare our findings, which only rely on harmonic interactions, with the predictions of other theories, which invoke anharmonic interactions and tunneling for explaining the low-temperature behavior of the specific heat.

The quantum loop and dimer models are archetypal correlated systems with local constraints. With natural foundations in statistical mechanics, they are of direct relevance to various important physical concepts and systems, such as topological order, lattice gauge theories, geometric frustrations, or more recently Rydberg array quantum simulators. However, how the thermal fluctuations interact with constraints has not been explored in the important class of nonbipartite geometries. Here we study, via unbiased quantum Monte Carlo simulations and field theoretical analysis, the finite-temperature phase diagram of the quantum loop model on the triangular lattice. We discover that the recently identified, “hidden” vison plaquette (VP) quantum crystal [X. Ran et al., Hidden orders and phase transitions for the fully packed quantum loop model on the triangular lattice, Commun. Phys. 7, 207 (2024)] experiences a finite-temperature continuous transition, which smoothly connects to the $(2+1)\mathrm{d}$ Cubic* quantum critical point separating the VP and ${\mathbb{Z}}_2$ quantum spin liquid phases. This finite-temperature phase transition acquires a unique property of “remnants of fractionalization” at finite temperature, in that, both the cubic order parameter—the plaquette loop resonance—and its constituent—the vison field—exhibit independent criticality signatures. This phase transition is connected to a three-state Potts transition between the lattice nematic phase and the high-temperature disordered phase. We discuss the relevance of our results for current experiments on quantum simulation platforms.

The coexistence of topological bands around the Fermi level ($E_{\mathrm{F}}$) and superconductivity provides a fundamental platform for exploring their interplay. However, few materials inherently display both properties. In this Letter, we demonstrate the coexistence of topological surface states at the $E_{\mathrm{F}}$ and superconductivity in ${\mathrm{NiTe}}_2$ single crystals, a material hitherto not recognized as superconducting. Quasiparticle interference measurements performed via scanning tunneling microscopy suggest the presence of topological surface states at the $E_{\mathrm{F}}$, which is further corroborated by density functional theory simulations. Experimental evidence for superconductivity is provided via electronic transport measurements and specific heat capacity analyses. Our results suggest that ${\mathrm{NiTe}}_2$ represents a promising platform for investigating the rich interplay between topological states and superconductivity.

Chiral phonons have recently been established to emerge in systems containing intrinsically chiral atomic structures or magnetic systems. Here we show that such intriguing chiral phonons can also be induced in nonmagnetic Kagome lattices that lack atomic structural chirality but harbor electronic chirality rooted in the presence of loop current order. This central finding is demonstrated using two types of loop current order, the restricted chiral flux phase characterized by a pure imaginary charge bond order and the more generalized chiral flux phase characterized by a complex charge bond order, as typified in layered $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A=\mathrm{Cs}$, Rb, K). At a mechanistic level, the time-reversal symmetry breaking caused by the electronic chirality is shown to pronouncedly influence their vibrational properties through electron-phonon coupling. The electronic chirality in either chiral flux phase is accompanied by a nonzero molecular Berry curvature, which in turn manifests as a nonlocal effective magnetic field of vectorial nature acting on the phonons. Consequently, the double degeneracy at each Brillouin zone corner is lifted, empowering chirality to the phonon modes. This Letter provides an indispensable component toward a more complete understanding of various chiral collective electronic phenomena in such structurally achiral systems.

We perform extensive simulations of the two-dimensional cavity-coupled electron gas in a modulating potential as a minimal model for cavity quantum materials. These simulations are enabled by a newly developed quantum-electrodynamical (QED) auxiliary-field quantum Monte Carlo method. We present a procedure to greatly reduce finite-size effects in such calculations. Based on our results, we show that a modified version of weak-coupling perturbation theory is remarkably accurate for a large parameter region. We further provide a simple parametrization of the light-matter correlation energy as a functional of the cavity parameters and the electronic density. These results provide a crucial step toward a numerical foundation for the development of the QED density functional theory, which was previously reliant on analytical approximations, to allow quantitative modeling of a wide range of systems with light-matter coupling.

We reveal a nonlinear magnetic dynamo in a Taylor-Couette flow at small magnetic Prandtl numbers $Pm\le 1$, which has been previously believed to exist only at higher $Pm\gtrsim 10$ in this flow. The amplitude of initial perturbations, $Pm$, and domain aspect ratio play a key role in the onset and evolution of the dynamo. It exists in two main states: a weak state dominated by large-scale modes and a strong, turbulent state with higher amplitude dominated by small-scale modes. These findings can be important for dynamo processes in various astrophysical objects with small $Pm$.

Recently, solar gamma rays produced by cosmic rays interacting with the solar atmosphere have been detected in the GeV to TeV energy range, revealing that cosmic rays are significantly affected by magnetic fields in the solar atmosphere. However, much of the observations remain unexplained by existing physical models. Using a semianalytic model, we demonstrate that magnetic fields at and below the photosphere with a large horizontal component could account for the approximately 1 TeV solar gamma rays observed by HAWC. This suggests that high-energy solar gamma rays could serve as a novel probe for magnetic fields beneath the photosphere, which in the future could help improve the understanding of solar magnetism, the key driver of space weather.

Phonon interactions from lattice anharmonicity govern thermal properties and heat transport in materials. These interactions are described by $n$th order interatomic force constants ($n$IFCs), which can be viewed as high-dimensional tensors correlating the motion of $n$ atoms, or equivalently encoding $n$-phonon scattering processes in momentum space. Here, we introduce a tensor decomposition to efficiently compress $n$IFCs for arbitrary order $n$. Using tensor learning, we find optimal low-rank approximations of $n$IFCs by solving the resulting optimization problem. Our approach reveals the inherent low dimensionality of phonon-phonon interactions and allows compression of the three- and four-IFC tensors by factors of up to ${10}^3–{10}^4$ while retaining high accuracy in calculations of phonon scattering rates and thermal conductivity. Calculations of thermal conductivity using the compressed $n$IFCs achieve a speedup by nearly 3 orders of magnitude with $>98\%$ accuracy relative to the reference uncompressed solution. These calculations include both three- and four-phonon scattering and are shown for a diverse range of materials (Si, HgTe, MgO, TiNiSn, and ${\mathrm{ZrO}}_2$). In addition to accelerating state-of-the-art thermal transport calculations, the method shown here paves the way for modeling strongly anharmonic materials and higher-order phonon interactions.

We derive many-body single and multireference wave functions for quantum Monte Carlo of periodic systems with an antisymmetric portion that explicitly integrates over the Brillouin zone of one-particle Bloch states. The wave functions are BCS-like determinants for singlets and Pfaffians for polarized states built with appropriate pair orbitals. This ab initio formalism is broadly applicable, e.g., to description of quasiparticle band gaps and optical excitations and to systems with complicated Fermi surfaces. It generalizes to spin-dependent interactions using two-component spinor pairs.

A magnetic impurity in a BCS superconductor induces the formation of a Shiba state and drives a local quantum phase transition. We generalize this concept to a one-dimensional superconductor with fractionalized excitations, where the dominant instability is superconducting. In this framework, conduction electrons fractionalize into gapless charge and gapped spin excitations. We show that magnetic impurity interacts exclusively with the spin degrees of freedom and induces a quantum phase transition. Furthermore, charge excitations influence dynamical observables, giving rise to the phenomenon we term the “fractionalized Shiba state.” At zero temperature, the tunneling spectrum exhibits universal power-law scaling with an exponent of $-1/2$ at half filling, stemming from the gapless charge modes that form a standard Luttinger liquid. Extending this analysis to finite temperatures reveals that the spectral features retain universal behavior at the critical point.