We propose and demonstrate an experimental scheme to engineer thermal baths with independently tunable temperatures and dissipation rates for the motional modes of a trapped-ion system. This approach enables robust thermal-state preparation and quantum simulations of open-system dynamics in bosonic and spin-boson models at well-controlled finite temperatures. We benchmark our protocol by experimentally realizing out-of-equilibrium dynamics of a charge-transfer model at different temperatures. We observe that, when the process occurs at a higher temperature, the transfer rate spectrum broadens, with reduced rates at small donor-acceptor energy gaps and enhanced rates at large gaps. We then employ our scheme to study local-temperature effects in a two-mode vibrationally assisted exciton transfer system, where we observe thermally activated interference pathways for excitation transfer.

Small deviations from isotropy in the arrival directions of Galactic cosmic rays serve as a unique probe of the local magnetic environment. In this Letter, we report observations of medium-scale anisotropies at energies above 10 TeV using the LHAASO-KM2A array. Our analysis identifies four regions of excess and four regions of deficit, each spanning angular scales of approximately 10°. Crucially, we detect significant energy-dependent shifts in the centroids of two excess regions: Region B and the newly identified Region $\tilde{\mathrm{D}}$. We also characterize the energy evolution of the fractional relative intensity across both excess and deficit regions. These findings imply that the observed anisotropies are shaped by the specific realization of the local turbulent magnetic field within the cosmic ray scattering length. Such energy-dependent behaviors impose strict constraints on local turbulence models and cosmic ray propagation theories.

We report a search for the rare decay $B^{+}\to K^{+}{\tau }^{+}{\tau }^{-}$ using $1.2\times {10}^9\mathbf{\Upsilon }(4S)$ mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle II experiments. We fully reconstruct the hadronic decay of one $B$ meson produced in the $\mathrm{\Upsilon }(4S)\to B^{+}{B}^{-}$ decay, and search for $B^{\pm }\to K^{\pm }{\tau }^{+}{\tau }^{-}$ candidates among the remaining collision products, reconstructing a charged kaon and leptonic decays of the $\tau$ leptons. We optimize the selection for best sensitivity and look for an excess over background at low values of the residual energy detected in the calorimeter after full event reconstruction. We observe no significant excess and set the limit $\mathcal{B}(B^{+}\to K^{+}{\tau }^{+}{\tau }^{-})<0.56\times {10}^{-3}$ at the 90% confidence level, improving on the only previous result by a factor of four.

The consistent matching of short-distance contributions and hadronic matrix elements is crucial for precise predictions of weak processes involving hadrons. In this Letter, we address this point for charged-current processes involving two pions—pion $\beta$ decay ${\pi }^{\pm }\to {\pi }^0{e}^{\pm }{\nu }_e$ and hadronic $\tau$ decays ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^0{\nu }_{\tau }$—whose decay rates depend on the so-called $\gamma W$ box correction. Using recent results from lattice QCD, we show how to formulate the matching beyond leading-logarithmic accuracy, in particular, how to cancel the dependence on the scheme choice for evanescent operators. As main results, we obtain a prediction for the decay rate of pion $\beta$ decay with theory uncertainties improved by a factor of 3, which renders theory uncertainties negligible for future determinations of $V_{ud}$ even beyond the reach of the PIONEER experiment, and an evaluation of isospin-breaking corrections to $\tau \to \pi \pi {\nu }_{\tau }$ with negligible uncertainty from the short-distance matching, as necessary for a future $\tau$-based determination of the hadronic-vacuum-polarization contribution to the anomalous magnetic moment of the muon.

Liquid marbles, droplets coated with a granular layer, are highly mobile as particles prevent capillary adhesion to the substrate. Yet their coating creates a static rolling friction, which we measure and model. Motion requires shear within the shell so that it is governed mainly by the grain density. This density controls yielding via a logistic function emerging as the particle network approaches percolation and increasing rapidly at close packing. More broadly, our system offers a simple platform for probing granular raft mechanics and measuring their effective surface tension.

Structural phase transition offers an effective means to modulate interfacial electronic states and accelerate electron transfer in water electrolysis. Here, we exploit a heat-induced monoclinic-to-tetragonal phase transition in ${\mathrm{VO}}_2$ to facilitate electron transfer at ${\mathrm{VO}}_2/{\mathrm{MO}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}(\mathrm{M}=\mathrm{Co},\mathrm{Ni},\mathrm{Fe})$ heterojunction interfaces. The thermally triggered electronic restructuring lowers the Fermi level of ${\mathrm{VO}}_2$ relative to ${\mathrm{MO}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}$, promoting the formation of high-valence active species. This significantly accelerates oxygen evolution reaction (OER) kinetics, driving a cascade of catalytic center activation and water oxidation. Our Letter establishes that coupling active catalysts with controllable phase transitions represents a viable strategy for synergistic heat-electricity activation in OER catalysis.

Accurate prediction of carrier mobility is critical for the discovery and design of next-generation electronic materials. Despite sustained progress, state-of-the-art ab initio methods remain limited by the approximate treatment of electron-phonon interactions at the density functional theory level. Here, we demonstrate that incorporating many-body $GW$ corrections to both the electronic band structure and electron-phonon couplings when solving the ab initio Boltzmann transport equation yields a mean absolute relative error of just 11% for electron mobilities across benchmark semiconductors, including Si, GaAs, GaP, diamond, and SiC. The common practice of neglecting $GW$ corrections to the electron-phonon interaction can lead to mobility errors exceeding 50%. The present findings highlight the importance of many-body $GW$ self-energy effects in carrier transport simulations and provides fundamental insights into how many-body electron-phonon interactions govern charge transport in crystalline solids.

We consider a family of generalized Rokhsar-Kivelson (RK) Hamiltonians, which are reverse-engineered to have an arbitrary edge-weighted superposition of dimer coverings as their exact ground state at the RK point. We focus on a quantum dimer model on the triangular lattice, with doubly periodic edge weights. For simplicity we consider a $2\times 1$ periodic model in which all weights are set to one except for a tunable horizontal edge weight labeled $\alpha$. We analytically show that the model exhibits a continuous quantum phase transition at $\alpha =3$, changing from a topological ${\mathbb{Z}}_2$ quantum spin liquid ($\alpha <3$) to a columnar ordered state ($\alpha >3$). The dimer-dimer correlator decays exponentially on both sides of the transition with the correlation length $\xi \propto 1/|\alpha -3|$ and as a power-law at criticality. The vison correlator exhibits an exponential decay in the spin liquid phase, but becomes a constant in the ordered phase, which we explain in terms of loop statistics of the double-dimer model. Using finite-size scaling of the vison correlator, we extract critical exponents consistent with the 2D Ising universality class. Additionally, we analytically show that the topological Rényi entropy of order $\infty$ (topological min-entropy) changes from log2 for the quantum spin liquid phase $\alpha <3$, to 0 for the ordered phase $\alpha >3$, thereby analytically confirming the topological nature of the phase transition.

Kardar-Parisi-Zhang (KPZ) scaling has been observed in discrete polariton lattices, enabled by engineered band structures that stabilize the condensate. Whether this universality extends to intrinsically continuous systems with natural noise regularization remains an open question. We propose and numerically demonstrate KPZ scaling in a continuous quasi-one-dimensional polariton condensate stabilized by optical confinement in the transversal direction. Large-scale simulations of the stochastic Gross-Pitaevskii equation, with experimentally relevant parameters, reveal temporal and spatial scaling exponents of the two-point phase correlation function, ${\beta }_C\approx 0.30(5)$ and ${\alpha }_C\approx 0.46(8)$, and Tracy-Widom one-point phase fluctuation statistics, yielding robust KPZ dynamics intrinsic to the continuous polariton fluid.

The ultrafast dynamics of exciton-polaritons (EPs) in single plasmonic nanocavities are of fundamental interest due to extreme mode confinement ($V\sim {10}^{-6}{\lambda }^3$), which enables few-exciton strong coupling and strong nonlinearity of EPs. However, directly probing transient evolutions of EPs in a single nanocavity has remained a challenge. Here, we develop an EP-resonant enhanced ultrafast difference-frequency generation (DFG) microscopy for directly visualizing EP dynamics in a single ${\mathrm{WSe}}_2$-Au nanocavity. By scanning the pump photon energy across the polariton resonances and recording the DFG intensity as a function of pump-probe delay, we construct two-dimensional maps that directly visualize the transient evolution of the high and low energy branches of EPs. The maps reveal that the EPs collapse suddenly and then revive within 2 ps with a saturation threshold below 2 pJ, indicating strong nonlinearity of EPs in the few-exciton saturation regime. This Letter provides a new approach for visualizing the nonequilibrium dynamics of EPs in a single plasmonic nanocavity, offering important experimental evidence for ultrafast manipulation of EPs.

Attempts to understand multipartite quantum nonlocality are thwarted by the difficulty of devising quantum Bell inequalities (QBI) for systems composed of more than a few separate parties. In this Letter, we introduce the notion of tight connectors, a class of tensors which, if contracted according to some simple rules, result in tight QBIs. The new inequalities are saturated by tensor network states whose structure mimics the corresponding network of connectors. We further formulate the connector property of “full self-testing,” which singles out a subset of tight connectors whose associated QBIs can only be saturated (modulo local isometries) by probing the corresponding tensor network state with specific measurement operators. We provide large analytic families of tight, full self-testing connectors that allow for the generation, via contraction, of $N$-partite QBIs with a ratio between the maximum quantum and classical values that grows exponentially with $N$. In turn, our method provides a modular recipe for the generation of extremal quantum behaviors and associated tight bounds in arbitrarily large systems.

At lower energies, the resonances in scattering experiments are often isolated. In quantum chaotic many-body, disordered, or generically stochastic systems, the resonances overlap at larger energies. Eventually, the Ericson regime is reached in which the cross section behaves like a random function. The scattering-matrix elements then follow a universal Gaussian distribution. For more than 60 years, the emergence of this robust additional universal behavior on top of the universal system stochasticity has awaited a concise analytical treatment. We derive the transition to the Ericson regime in the universal Heidelberg approach and prove the universal Gaussian distribution by a proper asymptotic expansion. We also obtain explicit formulas for the moments and for the cross-section distribution. We compare with microwave experiments and numerical simulations.

We revisit the Caldeira-Leggett model of quantum Brownian motion with Ohmic spectral density, and derive an additional contribution to the decoherence kernel in a new high-temperature limit at arbitrarily large cutoff frequency. This contribution reveals a novel mechanism for the classicalization of high-frequency quantum fluctuations. We further demonstrate that it leads to a Markovian master equation that is in guaranteed Lindblad form, and argue that this master equation describes the correct Markovian limit of quantum Brownian motion. Our approach considers in detail the behavior of the decoherence kernel at both the initial and final times of the process on the timescale of the bath memory.

During the charging process, interactions between a quantum battery and its charger generally generate quantum correlations, which may reduce the amount of work extractable from the battery alone. We show that, by coupling the system with an environment that can be continuously monitored, one can weaken these correlations and enhance work extraction beyond what is achievable in the ideal (closed system) limit. This general mechanism is illustrated using both a cavity-mediated spin-spin and a Dicke quantum battery model.

We performed searches for $K_L\to {\pi }^0{\pi }^{0}X$ where $X$ may be an axionlike particle that promptly decays to two photons, and the first search for $K_L\to {\pi }^0{\pi }^0\gamma \gamma$ at the KOTO experiment using data taken in 2021. The search is performed for $X$ mass in the range of $160–220\mathrm{MeV}/c^2$. Three events were observed in the signal region, with two events near an $X$ mass of $177\mathrm{MeV}/c^2$. This result led to a range of upper limits on the branching ratio, $\mathrm{BR}(K_L\to {\pi }^0{\pi }^{0}X)$ $<(1-20)\times {10}^{-7}$ at the 95% confidence level (CL). No events were observed for the analysis of $K_L\to {\pi }^0{\pi }^0\gamma \gamma$, setting an upper limit on the branching ratio, $\mathrm{BR}(K_L\to {\pi }^0{\pi }^0\gamma \gamma )$ $<1.69\times {10}^{-6}$ at the 95% CL.

According to quantum chromodynamics, at sufficiently high energy, the structure of hadrons reveals a dynamic equilibrium between gluon splitting and gluon recombination—a phenomenon known as saturation. The process of diffractive photonuclear production of a $J/\psi$ vector meson provides a direct insight into the gluon composition of hadrons. The $J/\psi$ production as a function of momentum transferred in the interaction, quantified by the Mandelstam-$t$ variable, serves as an excellent probe for studying the structure of hadrons within the impact-parameter plane, because different ranges in $t$ are sensitive to the dynamics of the gluon field at varying spatial size scales. The ALICE Collaboration has measured the energy dependence of incoherent photonuclear production of $J/\psi$ mesons off lead ions, at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$, for three Mandelstam-$t$ intervals. The energy dependence of the photonuclear cross section at the highest $|t|$ range measured, $(0.81<|t|<1.44){\mathrm{GeV}}^2$, is sensitive to subnucleonic structures of the Pb target. The increase of the cross section with energy at large $|t|$ shows evidence of suppression with respect to the increase seen at low $|t|$. The observed pattern of the energy evolution in data is similar to that of gluon saturation models.

An important validation of nucleosynthesis models of core-collapse supernovae is the comparison of radioisotope predictions to abundances inferred from observations of $\gamma$ rays emitted in remnants. One such isotope, ${}^{44}\mathrm{Ti}$, is especially sensitive to the ${}^{57}\mathrm{Ni}(p,\gamma ){}^{58}\mathrm{Cu}$ reaction rate. Despite this importance, no experimentally constrained rate exists for this reaction. It is thus crucial to determine this rate. GRETINA ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) was used along with the first use of the Enge split-pole spectrograph at Notre Dame to measure structure properties of ${}^{58}\mathrm{Cu}$ via the ${}^{58}\mathrm{Ni}({}^3\mathrm{He},t){}^{58}\mathrm{Cu}$ reaction. The combined analysis of these complementary data sets allows for precise determination of ${}^{58}\mathrm{Cu}$ level energies, and spins are constrained from analysis of the $\gamma$-ray decay. ${}^{44}\mathrm{Ti}$ yields were found to change by over 25% compared to previous estimates in model calculations using the new experimentally constrained reaction rate.