The first measurements of the top- and antitop-quark differential production cross sections and the top-quark charge asymmetry in the forward region are presented, using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. The total production cross sections of top and antitop quarks are also determined. Measurements are performed using the $\mu +b\text{-jet}$ final state within a fiducial region defined by $b$-jet $p_{\mathrm{T},\text{jet}}>50\mathrm{GeV}$ and pseudorapidity $2.2<{\eta }_{\text{jet}}<4.0$, with the muon from the $W$-boson decay required to have $p_{\mathrm{T},\mu }>25\mathrm{GeV}$ and $2.0<{\eta }_{\mu }<4.5$. The muon and $b$-jet system must satisfy $p_{\mathrm{T}}(\mu +\text{jet})>20\mathrm{GeV}$. The measured integrated production cross sections for the top and antitop quarks are ${\sigma }_t=0.95\pm 0.04\pm 0.08\pm 0.02\mathrm{pb}$, ${\sigma }_{\overline{t}}=0.81\pm 0.03\pm 0.07\pm 0.02\mathrm{pb}$, where the first uncertainty is statistical, the second systematic, and the third accounts for the luminosity uncertainty. The top-quark charge asymmetry is measured to be $A_C^t=0.08\pm 0.03\pm 0.01$, where the first uncertainty is statistical and the second is systematic. These results are consistent with next-to-leading order Standard Model predictions.

We study tunable, nanoscale, femtosecond coherent radiation based on a coupled nanowire pair structure, which is transversely excited by a strong, linearly polarized laser pulse. The structure can function as a nanoscale undulator: the electrons moving through the nanogap are driven by a spatially periodic, transverse optical near field. We show that the near field can actively shape the electron wave function by inducing both a periodic oscillation and a quantum squeezing of its width. We then validate this theoretical framework by numerically solving the relativistically corrected time-dependent Schrödinger equation. The generated femtosecond pulse trains can be spectrally, temporally, and spatially controlled. This framework establishes the transverse optical near-field interaction as a novel mechanism for spatiotemporally shaping electron wave functions, thereby illuminating a path to a versatile platform for an on-chip femtosecond coherent light source and applications in free-electron quantum optics.

We develop a theory that predicts the equilibrium states of a fluid contained in a capillary that has corners. Each section of the tube can take three states: completely wet state where the tube section is completely occupied by the fluid, partially wet state where only the corners are occupied by the fluid known as corner film or finger, and completely dry state. We calculate the phase diagram of these states for a square tube with rounded corners. It is shown that the partially wet state can exist only in a certain region in the parameter space spanned by the equilibrium contact angle and the corner curvature.

The experimental observation of half-integer-quantized thermal Hall conductivity in the Kitaev candidate material $\alpha \text{−}{\mathrm{RuCl}}_3$ has served as a signature of non-Abelian anyons through an associated chiral Majorana edge mode. However, both the reproducibility of the quantized thermal Hall conductivity and the fundamental nature of the associated heat carriers, whether bosonic or fermionic, are subjects of ongoing and vigorous debate. In a recent theoretical work, it was proposed that varying the sample geometry through creating constrictions can distinguish between different origins of the thermal Hall effect in magnetic insulators. Here, we provide experimental evidence of chiral fermion edge modes by comparing the thermal Hall effect of a geometrically constricted $\alpha \text{−}{\mathrm{RuCl}}_3$ sample with that of an unconstricted sample. In contrast to the unconstricted crystals where the thermal Hall signal fades below 5 K, the constricted crystals display a significant thermal Hall signal that remains measurable even at 2 K. This sharp difference agrees well with the theoretical prediction and provides compelling evidence for the contribution of chiral fermion edge modes to the thermal Hall effect in $\alpha \text{−}{\mathrm{RuCl}}_3$. More broadly, this work confirms that the geometry dependence of the thermal Hall effect can help identify chiral spin liquids in candidate materials like $\alpha \text{−}{\mathrm{RuCl}}_3$ and paves the way for the experimental realization of thermal anyon interferometry.

Topological physics in classical systems, such as photonic and acoustic systems, is fast becoming an exciting field in fundamental and applied research. However, almost all existing topological acoustic materials are restricted to systems with conventional lattices and specific time-space symmetries. Here, we present a unique design of topological phononic crystals with moiré superlattice that are constructed by simply sliding a layer of moiré phononic crystals. Assisted by the sliding degree of freedom, sliding moiré phononic crystals exhibit nontrivial topology characterized by a dynamical Chern number, leading to topological pumping of special topological moiré edge states that are completely insensitive to the edge geometry. More interestingly, moiré phononic crystals possess one-dimensional moiré flat bulk bands, giving rise to one-dimensional localized states in the bulk that result in an array of compact and nearly independent one-dimensional signal channels. Various applications such as acoustic communications and isolations in integrated devices can be anticipated from the intriguing acoustic one-dimensional localized bulk states and topological moiré edge states enriched by the sliding modulation.

We investigate layer codes, a family of three-dimensional stabilizer codes that achieves optimal scaling of code parameters and energy barrier, as candidates for self-correcting quantum memories. First, we introduce two decoding algorithms for layer codes with provable guarantees for local stochastic and adversarial noise, respectively. We then prove that layer codes constitute partially self-correcting quantum memories which outperform previously analyzed models such as the cubic and welded solid codes. Notably, we argue that partial self-correction without the requirement of efficient decoding is more common than expected, as it arises solely from a diverging energy barrier. This draws a sharp distinction between partially self-correcting systems and partially self-correcting memories. Another novel aspect of our work is an analysis of layer codes constructed from random Calderbank-Shor-Steane codes. We show that these random layer codes have optimal scaling (up to logarithmic corrections) of code parameters and energy barrier. Finally, we present numerical studies of their memory times and report behavior consistent with partial self-correction.

Entanglement generation is a cornerstone of quantum information science, yet its speed in Hermitian systems is fundamentally constrained by the coupling strength, a restriction known as the quantum speed limit. Here we demonstrate that this bound can be beaten by exploiting the unique topology of non-Hermitian systems near exceptional points (EPs). Using a pair of trapped ions, we engineer a parity-time symmetric Hamiltonian where the coalescence of eigenstates near the EP distorts the Hilbert space geometry, providing a shortcut for quantum state evolution. We observe that, as the system approaches the EP, the time required to generate a maximally entangled state is markedly reduced with respect to the limits imposed by the equivalent Hermitian interaction. We further uncover a fundamental physical trade-off whereby the acceleration of entanglement is intrinsically coupled to a reduction in the success probability, revealing the information cost of non-Hermitian speedup. Our results suggest that tailored dissipation, rather than being a source of decoherence, can serve as a powerful resource for accelerating quantum dynamics, offering a new paradigm for designing high-speed quantum gates and sensors in hardware-constrained platforms.

Quantum Mpemba effect describes an anomalous phenomenon of accelerated relaxation, which is of fundamental interest in the field of nonequilibrium thermodynamics. Conventional theories on this phenomenon strongly rely on the Born-Markovian approximation resulting in a Lindblad-type master equation whose evolution is governed by a Liouvillian superoperator. It has been demonstrated that exceptional points of the Liouvillian superoperator can induce the Mpemba effect in Markovian regimes. Moving beyond this Markovian limit, we here propose a mechanism for observing the quantum Mpemba effect in a general non-Markovian relaxation process by means of non-Markovian exceptional points. We verify the feasibility of this mechanism within a dissipative quantum harmonic oscillator model, which is exactly solvable and experimentally practical. Providing new insight into the interesting nonequilibrium dynamics, our Letter paves a way to accelerate the transfer of energy and information in quantum systems.

Randomness is a fundamental resource in quantum information, with crucial applications in cryptography, algorithms, and error correction. A central challenge is to construct unitary $k$ designs that closely approximate Haar-random unitaries while minimizing the costly use of non-Clifford operations. In this Letter, we present a protocol able to generate unitary $k$ designs on $n$ qubits, secure against any adversarial quantum measurement, with a system-size-independent number of non-Clifford gates. Our construction applies a $k$ design only to a subsystem of size $\mathrm{\Theta }(k)$, independent of $n$. This “seed” design is then “diluted” across the entire $n$-qubit system by sandwiching it between two random Clifford operators. The resulting ensemble forms an $ϵ$-approximate unitary $k$ design on $n$ qubits. We prove that this construction achieves full quantum security against adaptive adversaries using only $\tilde{O}(k^2\log {ϵ}^{-1})$ non-Clifford gates. If one requires security only against polynomial-time adaptive adversaries, the non-Clifford cost decreases to $\tilde{O}(k+{\log }^{1+c}{ϵ}^{-1})$. This is optimal, since we show that at least $\mathrm{\Omega }(k)$ non-Clifford gates are required in this setting. Compared to existing approaches, our method significantly reduces non-Clifford overhead while strengthening security guarantees to adaptive security as well as removing artificial assumptions between $n$ and $k$. These results make high-order unitary designs practically attainable in near-term fault-tolerant quantum architectures.

We present a combined experimental and numerical investigation of the transition from the classical to the ultimate regime of thermal turbulence in a supergravitational centrifugal convection system. The transition is found to be robust, with the critical Rayleigh number decreasing systematically as the Froude number, defined as the ratio of centrifugal to Earth’s gravity, decreases, highlighting the effect of residual gravity. Once the Rayleigh number reaches the transition threshold, the Stewartson layer induced by residual Earth gravity becomes comparable in thickness to the viscous boundary layer, and their interaction results in a coupled flow that distorts the viscous boundary layer, triggering its transition from laminar to turbulent flow and leading to a sharp increase in heat transport. These findings demonstrate the key role of the Stewartson layer induced by residual gravity in facilitating the transition to the ultimate regime in supergravitational centrifugal thermal convection.

A scaling framework unifying the markedly different and independently studied cylindrical and spherical shock convergence is presented. For ionizing argon, we show that the focal temperature becomes invariant to shock symmetry and initial shock conditions when scaled by the prefocus shock Mach number, after accounting for pressure effects. The resulting collapsed focal temperature–Mach number relation is governed by the thermodynamics of argon, up to an equilibrium temperature of 35 000 K. Such a scaling enables both predictive estimation of focal temperatures over a wide range of initial conditions and, conversely, determination of the parameters required to achieve a target temperature in a given medium.

We clarify the lore that anomaly-free symmetries are either on-site or can be transformed into on-site symmetries. We prove that any finite, internal, anomaly-free symmetry in a $1+1\text{D}$ lattice Hamiltonian system can be disentangled into an on-site symmetry by introducing ancillae and applying conjugation via a finite-depth quantum circuit. We provide an explicit construction of the disentangling circuit using Gauss’s law operators and emphasize the necessity of adding ancillae. Our result establishes the converse to a generalized Lieb-Schultz-Mattis theorem by demonstrating that any anomaly-free symmetry admits a trivially gapped Hamiltonian.

Geometric responses give rise to novel phenomena in charge and spin transport, which have been extensively studied in the context of the quantum geometry of Bloch states in periodic solids. In contrast, the geometry of Hamiltonian eigenvalues is often considered trivial. Here, we demonstrate that this seemingly trivial contribution can in fact generate a transverse spin current—reminiscent of the spin Hall effect—in the recently discovered class of centrosymmetric altermagnets. Using quantum perturbation theory, we identify two leading mechanisms under optical excitation combined with a static electric field: an effective-mass term and a group-velocity term, both rooted in the underlying band geometry and thus tied to spin splitting and band anisotropy that do not require inversion-symmetry breaking. Through a symmetry-based analysis of all centrosymmetric spin point groups, we establish how these mechanisms give rise to highly selective and switchable spin transport without accompanying charge flow. First-principles calculations on prototypical altermagnets $\alpha$-MnTe and ${\mathrm{MnF}}_2$ confirm our predictions, revealing experimentally accessible spin conductivities under moderate external fields.

We investigated the optical absorption spectra of the time-reversal-odd antiferromagnet ${\mathrm{ErCrO}}_3$ under an applied electric field ($\mathbf{E}$). This material, with its two distinct magnetic sites (${\mathrm{Er}}^{3+}$ and ${\mathrm{Cr}}^{3+}$), exhibits successive antiferromagnetic (AFM) transitions at $T_{\mathrm{N}}\approx 133\mathrm{K}$ and $T_{\text{SR}}\approx 10\mathrm{K}$. We observed nonreciprocal directional dichroism induced by $\mathbf{E}$ (ENDD) in the AFM phases, spanning the near-infrared to visible light regions. The phenomenon is explained by the electrotoroidic effect, where a magnetic toroidal moment is induced by the applied electric field. We also found that the spatial distributions of ENDD—reflecting magnetic domain structures—obtained at photon energies corresponding to ${\mathrm{Er}}^{3+}f\text{−}f$ and ${\mathrm{Cr}}^{3+}d\text{−}d$ transitions, were in good agreement. The result indicates a strong interplay between ${\mathrm{Er}}^{3+}4f$ and ${\mathrm{Cr}}^{3+}3d$ moments in the AFM phases of this rare-earth orthochromite. The combination of ENDD spectroscopy and microscopy is a powerful tool for elucidating site-specific magnetic information in time-reversal-odd antiferromagnets such as altermagnets.

Singlet fission and triplet-triplet annihilation (TTA) are spin-dependent phenomena critical to optoelectronics. The dynamics of spin populations during geminate triplet pair separation are crucial for controlling fission and TTA rates. We show that the Dzyaloshinskii-Moriya interaction (DMI) induces level crossings between spin manifolds, affecting spin populations and TTA rates in crystalline fission semiconductors. By investigating spin-dependent fluorescence in a triplet exciton pair with the magnetic field aligned along the fine structure tensor, we isolate the effect of DMI, as the triplet wave functions remain unaffected by the field. Our results reveal that DMI introduces additional TTA pathways that are forbidden by spin conservation, explaining the observed evolution of optically detected magnetic resonance signals with varying magnetic field. The magnitude of the DMI interactions needed to reproduce the experimental data is further confirmed by highly correlated wave function–based ab initio calculations. This Letter highlights the significant impact of DMI on the optical properties of triplet excitons, advancing our understanding of spin dynamics in these systems.

High-fidelity two-logical-qubit gates are essential for realizing fault-tolerant quantum computation with bosonic codes, yet experimentally reported fidelities have rarely exceeded 90%. Here, we propose a geometric phase engineering approach for implementing controlled-phase gates for binomially encoded logical qubits. This method leverages the structural simplicity of geometric drives to reduce the numerical optimization dimensionality while fully incorporating system nonlinearities, enabling fast and high-fidelity logical operations. As an example, we experimentally demonstrate a process fidelity of $97.4\pm 0.8\%$ with postselection to exclude leakage ($94.9\pm 0.7\%$ without post selection) for a controlled-Z gate between two lowest-order binomial codes, surpassing all previously reported two-logical-qubit gates in bosonic codes. This Letter demonstrates that geometric phase engineering provides an effective and experimentally feasible route to fast, high-fidelity logical operations in bosonic quantum processors.

Quantum sensing leverages quantum resources to surpass the standard quantum limit, yet many existing protocols rely on the preparation of complex entangled states and Hamiltonian engineering, posing challenges for universality and scalability. Here, we report an experimental implementation of a universal butterfly metrology protocol, proposed in Kobrin et al. [A universal protocol for quantum-enhanced sensing via information scrambling, arXiv:2411.12794.] demonstrating a scrambling-based approach for quantum-enhanced sensing on a superconducting quantum processor. By exploiting many-body information scrambling, we observe quantum-enhanced phase sensitivity beyond the standard quantum limit, with a scaling consistent with a factor of 2 of the Heisenberg limit for system sizes of up to 10 qubits after a normalization process. Importantly, we experimentally establish a connection between the enhanced sensitivity and the dynamics of the out-of-time-order correlator, and show that the buildup of scrambling-induced genuine multipartite entanglement underlies the observed sensitivity enhancement. Our results demonstrate a scalable approach for quantum-enhanced sensing in interacting many-body quantum systems.