Interactions of electron spins with rotational degrees of freedom during collisions or with external fields are fundamental processes that limit the coherence time of spin gases. We experimentally study the decoherence of hot cesium spins dominated by spin rotation interaction during binary collisions with ${\mathrm{N}}_2$ molecules or by absorption of near-resonant light. We report an order of magnitude suppression of the spin decoherence rate by either of those processes at low magnetic fields. This work extends the use of magnetic fields as a control knob, not only to suppress decoherence from random spin-conserving processes in the spin-exchange relaxation free (SERF) regime but also to suppress processes that relax electron spins rather than conserve them.

Time-periodic light field provides an emerging pathway for dynamically engineering quantum materials by forming hybrid states between photons and Bloch electrons. So far, experimental progress on light-field dressed states has been mainly focused on the occupied states; however, it is unclear if the transient photoexcited states above the Fermi energy $E_F$ can also be dressed, leaving the dynamical interplay between photoexcitation and light-field dressing elusive. Here, we provide direct experimental evidence for light-field dressing of the transient photoexcited surface states above $E_F$, which exhibits distinct dynamics with a delay response as compared to light-field dressed states below $E_F$. Our work reveals the dual roles of the pump pulse in both photoexcitation and light-field dressing, providing a more comprehensive picture with new insights on the light-induced manipulation of transient electronic states.

Higher Berry curvature (HBC) is the proposed generalization of Berry curvature to infinitely extended systems. Heuristically, HBC captures the flow of local Berry curvature in a system. Here, we provide a simple formula for computing the HBC for extended $d=1$ systems at the level of wave functions using the Schmidt decomposition. We also find a corresponding formula for matrix product states and show that for translationally invariant matrix product states this gives rise to a quantized invariant. We demonstrate our approach with an exactly solvable model and numerical calculations for generic models using the infinite density matrix renormalization group algorithm.

Strong coupling between vacuum fields and quantum matter occurs at the nanoscale and broadens the horizon of light-matter interaction. Nanoscale Casimir force, as an exhibition of vacuum fields, inevitably experiences the influence of surface electron responses due to their quantum character, which are ignorable in micron Casimir force. Here, we develop a three-dimensional conformal map method to tackle typical experimental configurations with surface electron contributions to Casimir force purposely and delicately included. Based on this method, we reveal that quantum surface responses (QSRs) can either enhance or suppress the nanoscale Casimir force, depending on materials and crystal facets. The mechanism is demonstrated to be the Casimir force softening, which results from QSRs effectively altering the distance seen by the Casimir interaction. With such an understanding, we then provide a recipe to handle the nanoscale Casimir force between nanoscale complex objects. Our findings not only highlight the interaction between QSRs and vacuum fields but also provide a recipe for theoretical and experimental investigation of nanoscale fluctuation-type problems.

We present a generalized Einstein relation for the friction coefficients associated with an underlying memory kernel in terms of observable time correlation functions. There is considerable freedom in the correlations involved, and this allows the expression to be tailored to the particular system to achieve numerical stability. We demonstrate this by recovering the site-specific friction coefficients from trajectories of a freely diffusing model trimer, and we show that the accuracy is greatly improved over established Volterra inversion methods for kernel extraction.

We present an experimental study on the perturbed evolution of Korteweg–de Vries soliton gases in a weakly dissipative nonlinear electrical transmission line. The system’s dynamics reveal that an initially dense, fully randomized soliton gas evolves into a coherent macroscopic state identified as a soliton condensate through nonlinear spectral analysis. The emergence of the soliton condensate is driven by the spatial rearrangement of the systems’s eigenmodes and by the proliferation of new solitonic states due to nonadiabatic effects, a phenomenon not accounted for by the existing hydrodynamic theories.

Classical nucleation theory (CNT) is built upon the capillarity approximation, i.e., the assumption that the nucleation properties can be inferred from the bulk properties of the melt and the crystal. Although the simplicity and usefulness of CNT cannot be overstated, experiments and simulations regularly uncover significant deviations from its predictions, which are often reconciled through phenomenological extensions of the CNT, fueling the debate over the general validity of the theory. In this Letter, we present a falsifiability test for any nucleation theory grounded in the capillarity approximation. We focus on cases where the theory predicts no differences in nucleation rates between different crystal polymorphs. We then introduce a system in which all polymorphs have the same free energy (both bulk and interfacial) across all state points. Through extensive molecular simulations, we show that the polymorphs exhibit remarkably different nucleation properties, directly contradicting predictions of CNT. We argue that CNT’s primary limitation lies in its neglect of structural fluctuations within the liquid phase.

Agitated granular media have a rich rheology: they exhibit Newtonian behavior at low shear rate and density, develop a yield stress at high density, and cross over to Bagnoldian shear thickening when sheared rapidly—making it challenging to encompass them in one theoretical framework. We measure the rheology of air-fluidized glass particles, spanning 5 orders of magnitude in shear rate. By comparing fluidization-induced to Brownian agitation, we show that all rheological regimes can be delineated by two dimensionless numbers—the Péclet number, Pe, and the ratio of shear-to-fluidization power, $\mathrm{\Pi }$—and propose a constitutive relation that captures all flow behaviors, qualitatively and quantitatively, in one unified framework.

Random nonreciprocal interactions between a large number of conserved densities are shown to enhance the stability of the system toward pattern formation. The enhanced stability is an exact result when the number of species approaches infinity and is confirmed numerically by simulations of the multispecies nonreciprocal Cahn-Hilliard model. Furthermore, the diversity in dynamical patterns increases with an increasing number of components, and novel steady states such as pulsating or spatiotemporally chaotic condensates are observed. Our results may help to unravel the mechanisms by which living systems self-organize via metabolism.

Biomolecules stochastically occupy different configurations that correspond to distinct functional states. Changing biochemical inputs such as rate constants alters the output probability distribution of configurations, and thus constitutes a form of computation. In the cell, such computations are often coupled to thermodynamic forces such as ATP hydrolysis that drive systems far from equilibrium, resulting in energy expenditure even during times when computations are not being performed. The information-theoretic advantage of this costly computational paradigm is unclear. Here we introduce a theoretical framework showing how much the thermodynamic force enables changes in probability distributions, quantified by the information gain, beyond what is possible at equilibrium. Using this framework, we derive a general expression relating the force to the maximum information gain in an arbitrary computation, revealing how small input changes can exponentially alter outputs. We numerically show that biomolecular systems can closely approach this universal bound, illustrating how energy expenditure is needed to achieve the information processing capabilities observed in nature.

We show that several models of interacting $XXZ$ spin chains subject to boundary driving and dissipation possess a subtle kind of time-reversal symmetry, making their steady states exactly solvable. We focus on a model with a coherent boundary drive, showing that it exhibits a unique continuous dissipative phase transition as a function of the boundary drive amplitude. This transition has no analog in the bulk closed system or in incoherently driven models. We also show the steady-state magnetization exhibits a surprising fractal dependence on interaction strength, something previously associated with less easily measured infinite-temperature transport quantities (the Drude weight). Our exact solution also directly yields driven-dissipative double-chain models that have pure, entangled steady states that are current carrying.

The $N$-qubit Greenberger-Horne-Zeilinger (GHZ) state is an important resource for quantum technologies. We consider the task of GHZ encoding using all-to-all interactions, which prepares the GHZ state in a special case, and is furthermore useful for quantum error correction, interaction-rate enhancement, and transmitting information using power-law interactions. The naive protocol based on parallelizing cnot gates takes O(1)-time of Hamiltonian evolution. In this work, we propose a fast protocol that achieves GHZ encoding with high accuracy. The evolution time $\mathrm{O}({\log }^{2}N/N)$ almost saturates the theoretical limit $\mathrm{\Omega }(\log N/N)$. Moreover, the final state is close to the ideal encoded one with high fidelity $>1–{10}^{-3}$, up to large system sizes $N\lesssim 2000$. The protocol only requires a few stages of time-independent Hamiltonian evolution; the key idea is to use the data qubit as control, and to use fast spin-squeezing dynamics generated by e.g., two-axis twisting.

The recent discovery of ultralong wavelength gravitational waves through the advent of pulsar timing arrays (PTA) has opened up new avenues for fundamental science. Here we show that every PTA source will be diffractively lensed by potentially hundreds of galactic disks transverse to its line of sight, leading to modest modulations in the strain, $\mathrm{\Delta }h/h\sim {10}^{-3}{\lambda }_{1\mathrm{pc}}^{-1}$, due to wave lensing effects. The induced interference, or scintillation, pattern will be resolvable by coherent PTAs and may be leveraged, alongside foreground redshift information, to make precise measurements of cosmic expansion. If future PTA experiments can achieve enough signal to noise to detect these small modulations, hundreds of redshift-distance pairs may be inferred from the diffractive lensing of an individual PTA source.

Using $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of $19{\mathrm{fb}}^{-1}$ collected by the BESIII detector at center-of-mass energies ranging from 4.13 to 4.70 GeV, we report the first evidence for a new excited ${\mathrm{\Omega }}^{-}$ hyperon, the $\mathrm{\Omega }(2109{)}^{-}$, through the process $e^{+}{e}^{-}\to \mathrm{\Omega }(2109{)}^{-}{\overline{\mathrm{\Omega }}}^{+}+\mathrm{c}.\mathrm{c}.$ with a significance of $4.1\sigma$. The mass and width of $\mathrm{\Omega }(2109{)}^{-}$ are measured to be $2108.5\pm {5.2}_{\mathrm{stat}}\pm {0.9}_{\mathrm{syst}}\mathrm{MeV}/c^2$ and $18.3\pm {16.4}_{\mathrm{stat}}\pm {5.7}_{\mathrm{syst}}\mathrm{MeV}$, respectively. We also present evidence for a new production mechanism for the previously identified $\mathrm{\Omega }(2012{)}^{-}$ via the process $e^{+}{e}^{-}\to \mathrm{\Omega }(2012{)}^{-}{\overline{\mathrm{\Omega }}}^{+}+\mathrm{c}.\mathrm{c}.$ with a significance of $3.5\sigma$.

Conventional absorption spectroscopy relies on coherent laser sources, and in turn suffers from the inherent limitation of shot noise, especially in estimating weak absorption. Here, we propose a measurement strategy with correlated photons to determine the weak absorption by distinguishing the output with and without photons, dubbed as the on-off measurement. We demonstrate that absorption spectroscopy that incorporates quantum correlations is capable of estimating weak absorption down to a single-photon level, even in noisy environments, achieving a precision comparable to that obtained through 1000 photons in conventional absorption spectroscopy. Our strategy provides a new method to probe fragile systems with weak absorption, avoiding the occurrence of light-induced damage.