Fermionic dark matter absorption on nuclear targets via neutral current interactions is explored using a nonrelativistic effective field theory framework. An analysis of data from the PICO-60 ${\mathrm{C}}_3{\mathrm{F}}_8$ bubble chamber sets leading constraints on spin-independent absorption for dark matter masses below $23\mathrm{MeV}/c^2$ and establishes the first limits on spin-dependent absorptive interactions. These results demonstrate the sensitivity of bubble chambers to low-mass dark matter and underscore the importance of absorption searches in expanding the parameter space of direct detection experiments.

We report results of a search for nuclear recoils induced by weakly interacting massive particle (WIMP) dark matter using the LUX-ZEPLIN (LZ) two-phase xenon time projection chamber. This analysis uses a total exposure of $4.2\pm 0.1$ tonne-years from 280 live days of LZ operation, of which $3.3\pm 0.1$ tonne-years and 220 live days are new. A technique to actively tag background electronic recoils from ${}^{214}\mathrm{Pb}$ $\beta$ decays is featured for the first time. Enhanced electron-ion recombination is observed in two-neutrino double electron capture decays of ${}^{124}\mathrm{Xe}$, representing a noteworthy new background. After removal of artificial signal-like events injected into the dataset to mitigate analyzer bias, we find no evidence for an excess over expected backgrounds. World-leading constraints are placed on spin-independent (SI) and spin-dependent WIMP-nucleon cross sections for masses $\ge 9\mathrm{GeV}/c^2$. The strongest SI exclusion set is $2.2\times {10}^{-48}{\mathrm{cm}}^2$ at the 90% confidence level and the best SI median sensitivity achieved is $5.1\times {10}^{-48}{\mathrm{cm}}^2$, both for a mass of $40\mathrm{GeV}/c^2$.

Internal gravity waves are an essential feature of stratified media, such as oceans and atmospheres. To investigate their dynamics, we perform simulations of the forced-dissipated kinetic equation describing the evolution of the energy spectrum of weakly nonlinear internal gravity waves. During the early evolution, three well-known nonlocal interactions, the elastic scattering, the induced diffusion, and the parametric subharmonic instability, together with a superharmonic resonance play a prominent role. In contrast, local interactions are responsible for anisotropic energy cascade on longer timescales. We reveal emergence of a condensate at small horizontal wave vectors that can be interpreted as a pure wave-wave interaction-mediated layering process.

The Rabi oscillation effect, which is among the most celebrated quantum phenomena arising from the wave nature of matter, has been widely studied in two-level quantum systems, superconductors, Bose-Einstein condensates, and photonic crystals. Here we show that the Rabi oscillation can be achieved in a laser-plasma system, in which a femtosecond probe laser pulse interacts with a defective plasma photonic crystal (PPC). The defective PPC is formed in underdense plasma irradiated by two groups of two-color driver laser pulses. By changing the plasma and driver laser parameters, the photonic band structure of defective PPCs as well as the Rabi oscillation frequency of a trapped probe laser pulse can be tuned flexibly. Moreover, the Rabi oscillation may result in the ladder climbing of trapped laser intensity by use of multiple probe pulses in the defective PPC. This not only provides a novel plasma optical approach to investigate the Rabi oscillation in a new system, but also offers a new route to manipulate the propagation of intense laser pulses for various applications.

The diversity of 2D materials and their van der Waals (vdW) stacking presents fertile ground for engineering novel multifunctional materials and quantum states of matter. This permits unique opportunities to tailor the electronic properties of vdW heterostructures by the insertion of only a single 2D material layer. However, such vdW materials engineering at the atomic scale has yet to be investigated for spin-charge interconversion phenomena. Here, we report on the control of these effects at the monolayer level, where a drastic increase in intensity and change in sign of THz spintronic emission are demonstrated by inserting a single layer of ${\mathrm{MoSe}}_2$ between ${\mathrm{PtSe}}_2$ and graphene in a fully epitaxial, large area stacked structure. By using a combination of spin and angle resolved photoemission and density functional theory to reveal the electronic and spin structures, we illustrate two different mechanisms relying on charge transfer and electronic hybridization for the formation of Rashba states, which are responsible for spin-charge conversion and hence the THz spintronic emission. These findings open new pathways to design, at the atomic scale, efficient THz spintronic emitters made of 2D materials and other spintronic devices based on spin-charge interconversion phenomena.

The Kirchhoff’s law of thermal radiation stating the equivalence of emissivity and absorptivity at the same wavelength, angle, and polarization, has completely constrained emission and absorption processes. Achieving strong nonreciprocal emission points to fundamental advances for applications such as energy harvesting, heat transfer, and sensing, but strong nonreciprocal thermal emission has not been experimentally realized. Here, we observe strong nonreciprocal thermal emission using a custom-designed angle-resolved magnetic thermal emission spectroscopy and an epitaxially transferred gradient-doped metamaterial. We show that under magnetic field, the metamaterial strongly breaks Kirchhoff’s law, with a difference between emissivity and absorptivity at the same wavelength and angle reaching as high as 0.43. Significant nonreciprocal emission persists over broad spectral and angular ranges. The demonstration of strong nonreciprocal thermal emission and the approach can be useful for systematic exploration of nonreciprocal thermal photonics for thermal management, infrared camouflage, and energy conversion.

Fermionic superfluid junctions typically exhibit suppressed thermal and spin transport due to the presence of a pairing gap but allow coherent particle transport. While dissipation generally weakens coherent transport, it can also induce excitations that open other transport channels. In this work, we experimentally study a one-dimensional superfluid junction of strongly interacting fermions with local particle loss and observe dissipation-induced thermal and spin transport that appear to saturate at strong dissipation. Notably, in this regime, the measured thermal and spin conductances are comparable to the universal quantized conductance of one-dimensional ideal Fermi gas. Qualitatively similar behavior is observed for two dissipation mechanisms, either spin-imbalanced or pairwise losses. Our findings provide new insights into transport in interacting open quantum systems and suggest possibilities of dissipative control of spin and thermoelectric transport.

Feature-learning deep nets progressively collapse data to a regular low-dimensional geometry. How this emerges from the collective action of nonlinearity, noise, learning rate, and other factors, has eluded first-principles theories built from microscopic neuronal dynamics. We exhibit a noise–nonlinearity phase diagram that identifies regimes where shallow or deep layers learn more effectively and propose a macroscopic mechanical theory that reproduces the diagram and links feature learning across layers to generalization.

Multivariate information theory provides a general and principled framework for understanding how the components of a system are connected. Existing analyses are coarse in nature—built up from characterizations of discrete subsystems—and can be computationally prohibitive. In this work, we propose to study the continuous space of possible descriptions of a composite system as a window into its organizational structure. A description consists of specific information conveyed about each of the components, and the space of possible descriptions is equivalent to the space of lossy compression schemes of the components. We introduce a machine-learning framework to optimize descriptions that extremize key information theoretic quantities used to characterize organization, such as total correlation and O-information. Through case studies on spin systems, sudoku boards, and letter sequences from natural language, we identify extremal descriptions that reveal how system-wide variation emerges from individual components. By integrating machine learning into a fine-grained information theoretic analysis of composite random variables, our framework opens a new avenues for probing the structure of real-world complex systems.

Quantum Hall Fabry-Pérot interferometers are sensitive to the properties of bulk quasiparticles enclosed by the interferometer loop, with the interference phase containing information about both the quasiparticle statistics and the Coulomb-mediated bulk-edge coupling. Previous studies have explored the role of the bulk-edge coupling in an equilibrium picture where quasiparticles enter and exit the interferometer rapidly compared to the timescale over which the interferometer phase is measured. Here, we present data from a monolayer graphene quantum Hall interferometer in the integer quantum Hall regime at $\nu =-1$ and $\nu =-2$. Quantum interference shows phase slips associated with the entrance of quasiparticles to the interferometer bulk. Tracing the dependence of these phase slips on the magnetic field, we show that the equilibration time can become as long as several minutes. We further use our multigated geometry to identify two classes of phase slips. The first is associated with the addition of a quasiparticle to a bulk “puddle” of quasiparticles uniformly coupled to the entire chiral edge state, while the second is associated with the addition of a quasiparticle trapped by a defect site that couples predominantly to the closest portion of the edge.

Phase transitions driven by external parameters are fundamental to condensed matter physics, providing critical insights into symmetry breaking and emergent phenomena. Recently, ferrimagnetic ${\mathrm{Mn}}_3{\mathrm{Si}}_2{\mathrm{Te}}_6$ has attracted considerable attention for its magnetic-field-induced insulator-metal transitions and current-driven phase transitions, but the role of applied currents in the magnetic phase remains poorly understood. Here, we employ local magnetization probes and time-resolved transport measurements to investigate the current-induced phase transitions. Magnetic force microscopy with controlled current flow reveals the evolution of ferrimagnetic domains and a first-order-like magnetic phase transition with an abrupt voltage jump. The measurements with rectangular pulsed currents reveal that the time evolution of resistance closely mirrors the resistance-temperature profile, highlighting the role of heat accumulation and a positive-feedback mechanism in the current-induced phase transitions. Furthermore, we demonstrate that the intrinsic current-voltage characteristics adhere to Ohm’s law, displaying linearity across various magnetic fields and temperatures. Our work advocates for a cautious approach in distinguishing between genuine current-induced nonequilibrium quantum states and thermal effects.

${\text{CoTi}}_2{\mathrm{O}}_5$ has the paradox that low temperature static magnetic order is incompatible with the crystal structure owing to a mirror plane that exactly frustrates magnetic interactions. Despite no observable structural distortion with diffraction, ${\text{CoTi}}_2{\mathrm{O}}_5$ does magnetically order below $T_N\sim 25\mathrm{K}$ with the breaking of spin ground state degeneracy proposed to be a realization of the spin Jahn-Teller effect in analogy to the celebrated orbital Jahn-Teller transition. We apply neutron and Raman spectroscopy to study the dynamics of this transition in ${\text{CoTi}}_2{\mathrm{O}}_5$. We find anomalous acoustics associated with a symmetry breaking strain that characterizes the spin Jahn-Teller transition. Crucially, the energy of this phonon coincides with the energy scale of the magnetic excitations, and has the same symmetry of an optic mode, observed with Raman spectroscopy, which atypically softens in energy with decreasing temperature. Taken together, we propose that the energetics of the spin Jahn-Teller effect in ${\text{CoTi}}_2{\mathrm{O}}_5$ are related to cooperative magnetoelastic fluctuations as opposed to conventional soft critical dynamics which typically drive large measurable static displacements.

Laser excitation of ${}^{229}\mathrm{Th}$ nuclei in doped wide band gap crystals has been demonstrated recently, opening the possibility of developing ultrastable solid-state clocks and sensitive searches for new physics. We develop a quantitative theory of the internal conversion (IC) of isomeric ${}^{229}\mathrm{Th}$ in solid-state hosts and elucidate a crucial requirement in choosing the solid-state hosts in nuclear clock applications. The IC of the isomer proceeds by resonantly exciting a valence band electron to a defect state, accompanied by multiphonon emission. We demonstrate that, if the process is energetically allowed, it generally quenches the isomer on a millisecond timescales, much faster than the isomer’s radiative lifetime, despite ${}^{229}\mathrm{Th}$ being in the $+4$ charge state in the valence band.

We demonstrate the use of finite-size fermionic projected entangled pair states, in conjunction with variational Monte Carlo, to perform accurate simulations of the ground state of the 2D Hubbard model. Using bond dimensions of up to $D=28$, we show that we can surpass state-of-the-art density matrix renormalization group energies that use up to $m=32000$ SU(2) multiplets on eight-leg ladders. We further apply our methodology to $10\times 16$, $12\times 16$, and $16\times 16$ lattices at $1/8$ hole doping and observe the dimensional crossover between stripe orientations. Our Letter shows the power of finite-size fermionic tensor networks to resolve the physics of the 2D Hubbard model and related problems.

The precision measurement of the tritium $\text{β}$-decay spectrum performed by the KATRIN experiment provides a unique way to search for general neutrino interactions (GNIs). All theoretically allowed GNI terms at dimension 6 involving neutrinos are incorporated into a low-energy effective field theory, and can be identified by specific signatures in the measured tritium $\text{β}$ spectrum. In this Letter an effective description of the impact of GNIs on the $\text{β}$ spectrum is formulated and the first constraints on the effective GNI parameters are derived based on the $4\times {10}^6$ electrons collected in the second measurement campaign of KATRIN in 2019. In addition, constraints on selected types of interactions are investigated, thereby exploring the potential of KATRIN to search for more specific new physics cases, including a right-handed W boson, a charged Higgs boson, or leptoquarks.

We present an extension of Landau’s theory of phase transitions by incorporating the topology of the order parameter. When the order parameter comprises several components arising from multiplicity in the same irreducible representation of symmetry, it can possess a nontrivial topology and acquire a Berry phase under the variation of thermodynamic parameters. To illustrate this idea, we investigate the superconducting phase transition of an electronic system with tetragonal symmetry and an attractive interaction involving two partial waves, both transforming in the trivial representation. By analyzing the time-dependent Ginzburg-Landau equation in the adiabatic limit, we show that the order parameter acquires a Berry phase after a cyclic evolution of parameters. We study two concrete models—one preserving time-reversal symmetry and one breaking it—and demonstrate that the nontrivial topology of the order parameter originates from thermodynamic analogs of gapless Dirac and Weyl points in the phase diagram. Finally, we identify an experimental signature of the topological Berry phase in a Josephson junction.

Quantum states featuring extensive multipartite entanglement are a resource for quantum-enhanced metrology, with sensitivity up to the Heisenberg limit. However, robust generation of these states using unitary dynamics typically requires all-to-all interactions among particles. Here, we demonstrate that optimal states for quantum sensing can be generated with sparse interaction graphs featuring only a logarithmic number of couplings per particle. We show that specific sparse graphs with long-range interactions can approximate the dynamics of all-to-all spin models, such as the one-axis twisting model, even for large system sizes. The resulting sparse coupling graphs and protocol can also be efficiently implemented using dynamic reconfiguration of atoms in optical tweezers.

The capability to measure the state of a neutral atom is vital to an atom-based quantum network, for applications including distributed quantum computing and long-distance quantum communication. However, single neutral atoms suffer from low achievable photon scattering rate and shallow trapping potential, which limits the fidelity and speed of state readout process. Here, by coupling a single neutral atom with a high-finesse fiber-based Fabry-Pérot microcavity in the Purcell regime, we realize strong enhancement of the atomic photoemission rate and high overall system efficiency, which enables ultrafast and high-fidelity discrimination of bright and dark hyperfine states of the atom. The readout fidelity can reach 99.1(2)% within 200 ns and 99.985(8)% within $9\mathrm{\mu }\mathrm{s}$. Furthermore, we demonstrate that state preparation via optical pumping can be efficiently accelerated by a real-time decision protocol based on ultrafast state readout. This work demonstrates the potential to serve as a high-performance atom-photon interface and paves the way to the implementation of a practical atom-based quantum network.

Optoelectronic metadevices control and enhance light-matter interactions by modulating the local optical field that interacts with emitters. However, the optical property of the highly localized mode in the plasmonic metasurface is sensitive to local disorders arising from experimental fluctuations. Recently, the nonlocal mode of metasurfaces has been attracting growing interest because the coupling within the array of plasmonics results in long-range ordering and collective resonances. Here we demonstrate the topological edge states and the nonlocal modes of Au bow ties in a photonic crystal (PHC) lattice. The strong coupling between plasmonic modes and PHC bands opens the topological band gap at the edge of the Brillouin zone and forms the nonlocal mode having a resonant energy insensitive to fluctuations in Au length, resulting in a robust Purcell effect for quantum dots (QDs) coupling with the nonlocal mode in metadevices. The topological band gap and robust enhancement indicate great potential for the nonlocal plasmonic metasurface in quantum photonic devices with novel functionalities.

Here we report the experimental demonstration of the nonlinear non-Hermitian skin effect (NHSE) in an effective Kerr nonlinear temporal photonic lattice, where the high-power requirements and lack of tunability intrinsic to optical materials are overcome by an artificial nonlinearity arising from optoelectronic feedforward. Thanks to Kerr self-trapping, the nonlinear NHSE is demonstrated to possess much better localization strength and robustness at the preferred boundary compared to the linear case. Away from the preferred boundary, Kerr self-trapping can even inhibit NHSE-induced transport and form stable skin solitons. Harnessing the nonlinearity-controlled NHSE, we judiciously design an optical router with a flexibly tuned output port. Our findings promise great applications in robust signal transmission, routing, and processing.