Deep thermalization refers to the emergence of Haar-like randomness from quantum systems upon partial measurements. As a generalization of quantum thermalization, it is often associated with high complexity and entanglement. Here, we introduce computational deep thermalization and construct the fastest possible dynamics exhibiting it at infinite effective temperature. Our circuit dynamics produce quantum states with low entanglement in polylogarithmic depth that are indistinguishable from Haar random states to any computationally bounded observer. Importantly, the observer is allowed to request many copies of the same residual state obtained from partial projective measurements on the state—this condition is beyond the standard settings of quantum pseudorandomness but natural for deep thermalization. In cryptographic terms, these states are pseudorandom and pseudoentangled, and crucially, they retain these properties under local measurements. Our results demonstrate a new form of computational thermalization in which thermal-like behavior arises from structured quantum states endowed with cryptographic properties instead of from highly unstructured ensembles. The low resource complexity of preparing these states suggests scalable simulations of deep thermalization using quantum computers. Our Letter also motivates the study of computational quantum pseudorandomness beyond $\mathsf{BQP}$ observers.

The sensitivity of direct detection experiments depends on the phase-space distribution of dark matter near the Sun, which can be modeled theoretically using cosmological hydrodynamical simulations of Milky Way–like galaxies. However, capturing the halo-to-halo variation in the local dark matter speeds—a necessary step for quantifying the astrophysical uncertainties that feed into experimental results—requires a sufficiently large sample of simulated galaxies, which has been a challenge. In this Letter, we quantify this variation with nearly 100 Milky Way–like galaxies from the tng50 simulation, the largest sample to date at this resolution. Moreover, we introduce a novel phase-space scaling procedure that endows every system with a reference frame that accurately reproduces the local standard-of-rest speed of our Galaxy, providing a principled way of extrapolating the simulation results to real-world data. The ensemble of predicted speed distributions is well characterized by the standard halo model, a Maxwell-Boltzmann distribution truncated at the escape speed, though the individual distributions can deviate from it, especially at high speeds. The dark matter–nucleon cross section limits placed by these speed distributions vary by $\sim 60\%$ about the median. This places the $1\sigma$ astrophysical uncertainty at or below the level of the systematic uncertainty of current ton-scale detectors, even down to the energy threshold. The predicted uncertainty remains unchanged when subselecting on those tng50 galaxies with merger histories similar to the Milky Way. Tabulated speed distributions, as well as Maxwell-Boltzmann fits, are provided for use in computing direct detection bounds or projecting sensitivities.

We analyze the correlation between the energy, momentum, and spatial entanglement produced by two luminal jets in the massive Schwinger model. Using tensor network methods, we show that for $m/g>1/\pi$, in the vicinity of the strong- to weak-coupling transition, a nearly perfect and chargeless effective fluid behavior appears around the midrapidity region with a universal energy-pressure relationship. The evolution of energy and pressure is strongly correlated with the rise of the spatial entanglement entropy, indicating a key role of quantum dynamics. Some of these observations may be used to analyze high multiplicity jet fragmentation events, energy-energy and energy-charge correlators at current collider energies.

We provide the first experimental cross section of the ${}^{73}\mathrm{As}(p,\gamma ){}^{74}\mathrm{Se}$ reaction to constrain one of the main destruction mechanisms of the $p$ nucleus ${}^{74}\mathrm{Se}$ in explosive stellar environments. The measurement was done using a radioactive ${}^{73}\mathrm{As}$ beam at effective center-of-mass energies of 2.9 and $2.3\mathrm{MeV}/\mathrm{nucleon}$. Along with the total cross-section measurement, statistical properties of the ${}^{74}\mathrm{Se}$ compound nucleus were extracted, constraining the reaction cross section in the upper Gamow window of the $\gamma$ process. The impact of the experimentally constrained reaction rate on ${}^{74}\mathrm{Se}$ production in Type II supernovae was investigated through Monte Carlo one-zone network simulations. The results indicate that the overproduction of ${}^{74}\mathrm{Se}$ by Type II supernova models cannot be resolved by nuclear physics alone and point toward the need for a more detailed understanding of the astrophysical conditions of relevance for the $\gamma$ process.

We combine cryogenic storage of fullerene anions up to minutes with laser photo-detachment spectroscopy and measure the electron affinities to be 2.684(3) eV for ${\mathrm{C}}_{60}$ and 2.7665(3) eV for ${\mathrm{C}}_{70}$, which settle long-standing issues concerning these values. We find that ${\mathrm{C}}_{70}^{-}$ cools more efficiently than ${\mathrm{C}}_{60}^{-}$ and that this is due to differences in photon emission from electronically excited states populated by inverse internal conversion (recurrent fluorescence). We also find that intramolecular vibrational redistribution is no longer effective at low internal energies of ${\mathrm{C}}_{60}^{-}$ or ${\mathrm{C}}_{70}^{-}$. Radiative cooling becomes extremely slow below intramolecular vibrational redistribution decoupling energies of 0.32(2) and 0.13(3) eV for ${\mathrm{C}}_{60}^{-}$ and ${\mathrm{C}}_{70}^{-}$, respectively.

In open quantum systems, the interaction of the system with its environment gives rise to two types of symmetry: a strong one, where the system’s symmetry charge is conserved exactly, and a weak one, where the system can exchange symmetry charge with the environment but still preserve symmetry at the ensemble level. While generic open quantum systems feature weak symmetries only, the symmetry-protected topological response for bosonic (spin) systems has only been considered in the stricter setup with additional strong symmetries. Here, we address the generic case and demonstrate that weak symmetries alone can protect topological responses that distinguish different phases of matter. For bosonic systems, focusing on one-dimensional mixed states described by locally purifiable density operators, we propose a quantized response characterizing qualitatively distinct phases. It is detectable via the decay behavior of different string order parameters. We illustrate our general results through a noisy Affleck-Kennedy-Lieb-Tasaki model. In particular, we show that the coupling to the environment can induce a phase transition to a state protected by weak symmetries, without a pure-state or strong-symmetry analog.

We report a comparative theoretical study of molecular-frame angular emission distributions of high-energy electrons released from the $\mathrm{O}1s$ inner shell of methyloxirane and trifluoromethyloxirane molecules via photoionization and, alternatively, ionization by a Compton scattering of high-energy photons. We demonstrate that the high-energy photo- and Compton electrons can be employed to determine the absolute configuration of these chiral molecules via diffraction imaging. This is particularly important in cases where the single-molecule handedness cannot be recognized from ionic fragmentation patterns. Thereby, we establish high-energy photoionization and ionization by Compton scattering as additional complementary tools for chiral recognition in the gas phase.

We report the observation of a broad magnetic Feshbach resonance with a large background scattering length in an ultracold fermionic mixture of ${}^{23}\mathrm{Na}{}^{40}\mathrm{K}$ molecules and ${}^{40}\mathrm{K}$ atoms, with both species prepared in their lowest hyperfine states. The Feshbach resonance is characterized by measuring resonantly enhanced loss rates and elastic scattering cross sections via cross-species thermalization. The large background scattering length can drive the atom-molecule mixture into the hydrodynamic regime when the magnetic field is far from the resonance. We observe that the center-of-mass motions of the atoms and molecules are phase locked and oscillate with a common frequency due to hydrodynamic drag effects. This broad atom-molecule Feshbach resonance with its large background scattering length opens up a new avenue toward studying strongly interacting fermionic gases with mass imbalance.

Creating highly spin-squeezed states for quantum metrology surpassing the standard quantum limit is a topic of great interest. Spin squeezing has been achieved by either entangling different atoms in an ensemble, or by controlling the multilevel internal spin state of an atom. Here, we experimentally demonstrate combined internal and collective spin squeezing in a hot atomic ensemble with $\sim {10}^{11}$ rubidium atoms. By synergistically combining these two types of squeezing and carefully aligning their squeezing quadratures, we have achieved a metrologically relevant spin squeezing of $-6.21\pm 0.84\mathrm{dB}$, significantly outperforming the results obtained by utilizing either type of squeezing alone in our system. Our approach provides a new perspective on fully harnessing the degrees of freedom inherent in quantum states of an atomic ensemble.

We report the observation of transverse intensity fluctuations—spikes—in synchrotron radiation from a single undulator cell at the European XFEL after monochromatization. Autocorrelation analysis of the recorded events confirms that these fluctuations originate from the partial transverse coherence of the radiation. By calculating the second-order autocorrelation function, we determined the averaged transverse slice size of the electron beam along the SASE1 undulator. The measurements were performed with 5.49 keV x-ray photons using a commissioning silicon monochromator with (111) Bragg reflection and an x-ray imager. This technique enables undulator cell-by-cell diagnostics of the transverse electron beam size at free-electron laser facilities.

We study topological flat bands with distinct features that deviate from conventional Landau level behavior. We show that even in the ideal quantum geometry limit, moiré flat band systems can exhibit physical phenomena fundamentally different from Landau levels without lattices. In particular, we find new fractional quantum Hall states emerging from multiband vortexable systems, where multiple exactly flat bands appear at the Fermi energy. While the set of bands as a whole exhibits ideal quantum geometry, individual bands separately lose vortexability, and thus making them very different from a stack of Landau levels. At certain filling fractions, we find fractional states whose Hall conductivity deviates from the filling factor. Through careful numerical and analytical studies, we rule out all known mechanisms—such as fractional quantum Hall crystals or separate filling of trivial and topological bands—as possible explanations. Leveraging the exact solvability of vortexable systems, we use analytic Bloch wave functions to uncover the origin of these new fractional states, which arises from the commensurability between the moiré unit cell and the magnetic unit cell of an emergent effective magnetic field.

Augmenting a train of bright phase-modulated laser-light pulses of a coherent communications system with infinitesimally small quantum photons per pulse—entangled across several time bins—prepared by splitting squeezed light in a temporal-mode interferometer can dramatically enhance a homodyne receiver’s ability to detect a sudden change in the channel loss, by up to a factor that is the inverse of the pre-change loss, without affecting the communications rate. We discuss the quantum limit of quickest change detection, and the problem of joint communications and change detection that our Letter opens up.

A search for cosmological axions has been performed by scanning a frequency region of 38 MHz centered at about 10.2 GHz, corresponding to an axion mass $m_a\simeq 42\mathrm{\mu }\mathrm{eV}$. The QUAX experimental apparatus, a haloscope comprised of a 1-liter volume tunable cavity immersed in an 8 T magnetic field and a quantum-limited detection chain, set limits on the axion-photon coupling at the ${10}^{-14}{\mathrm{GeV}}^{-1}$ level. As no signal candidate has been observed, viable hadronic axion models are ruled out in a currently preferred postinflationary region $m_a>40\mathrm{\mu }\mathrm{eV}$.

The equivalence principle and the inverse-square law of gravity could be violated at short distances (${10}^{-6}–{10}^{-12}\mathrm{m}$) by scalars sporting a coupling $g_N$ to nucleons and mass $\mathrm{eV}\lesssim m_{\varphi }\lesssim \mathrm{MeV}$. We show for the first time that stringent bounds on the existence of these scalars can be derived from the observed cooling of nearby isolated neutron stars (NSs). Although NSs can only be used to set limits comparable to the classic supernova (SN) 1987A cooling bound in the case of pseudoscalars such as the QCD axion, the shallow temperature dependence of the scalar emissivity results in a huge enhancement in the effect of $\varphi$ on the cooling of cold NSs. As we do not find evidence of exotic energy losses, we can exclude couplings down to $g_N\lesssim 5\times {10}^{-14}$. Our new bound supersedes all existing limits on scalars across 6 orders of magnitude in $m_{\varphi }$. These conclusions also extend to Higgs-portal models, for which the bound on the scalar-Higgs mixing angle is $\sin \theta \lesssim 6\times {10}^{-11}$.

We uncover a striking connection between conformal blocks and fractional calculus. By employing a modified form of half derivatives, we derive explicitly the exact form of the three-dimensional conformal block, expressed as the product of two hypergeometric ${}_4{F}_3$ functions. This result provides a rigorous proof of Hogervorst’s formula, conjectured nearly a decade ago. Furthermore, we demonstrate its implications for the conformal bootstrap, potentially leading to new analytical techniques and numerical tools that deepen our understanding of conformal field theory.

We demonstrate coherent, measurement-free optical feedback control of a levitated nanoparticle, achieving phonon occupations down to a few hundred phonons. Unlike measurement-based feedback, this all-optical scheme preserves the correlations between mechanical motion and the feedback signal. Adjustment of the feedback phase and delay provides precise and tunable control over the system dynamics. The ultimate cooling performance is currently limited by phase noise, which we analyze within a theoretical framework that outlines the constraints and prospects for reaching the motional ground state. Our results establish coherent feedback as a powerful tool for quantum control of levitated systems, extending beyond center-of-mass cooling.

In the two-dimensional (2D) limit, the quantum fluctuation is significantly enhanced which could induce a quantum phase transition. Investigating the quantum criticality is an effective approach to elucidate the underlying physics of 2D superconductivity. Here we report the observation of different universality classes of quantum criticality at the superconducting ${\mathrm{LaAlO}}_3/{\mathrm{KTaO}}_3$ (111) interface, i.e., the normal quantum Griffiths singularity (QGS) and the anomalous QGS. The switch of the quantum criticality class is observed from the normal QGS in a lower $T_{\mathrm{c}}$ sample with weaker spin-orbit coupling (SOC) to the anomalous QGS in a higher $T_{\mathrm{c}}$ sample with stronger SOC. Moreover, owing to the remarkable SOC strength, the higher $T_{\mathrm{c}}$ sample exhibits an unprecedentedly enhanced quantum fluctuation at an unusually elevated temperature approaching the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature $T_{\mathrm{BKT}}$. This Letter provides comprehensive recognition of the different quantum criticality classes in the same superconducting ${\mathrm{LaAlO}}_3/{\mathrm{KTaO}}_3$ (111) system, which deepens the understanding of the superconducting mechanism of interfacial superconductors.

We investigate automated in situ optimization of the potential landscape in a quantum point contact device, using a $3\times 3$ gate array patterned atop the constriction. Optimization is performed using the covariance matrix adaptation evolutionary strategy, for which we introduce a metric for how “steplike” the conductance is as the channel becomes constricted. We first perform the optimization of the gate voltages in a tight-binding simulation and show how such in situ tuning can be used to mitigate a random disorder potential. The optimization is then performed in a physical device in experiment, where we also observe a marked improvement in the quantization of the conductance resulting from the optimization procedure.

The pursuit of a lattice analog for Landau levels has been a central theme in condensed matter physics. Although the correspondence between Chern bands and the lowest Landau level has been widely studied, a lattice realization of the first Landau level remains elusive. Here, we construct a minimal lattice model that provides a concrete orbital description of both the lowest and first Landau levels. Using maximally localized Wannier functions with $s$, $p_{-}$, and $p_{+}$ orbital character, we develop a three-orbital model in which the two lowest Chern bands are flat and each carries a Chern number $\mathcal{C}=1$. The band topology arises from a sequence of ideal band inversions between Wannier states at the $\mathrm{\Gamma }$ and $K$ points in momentum space, establishing an adiabatic connection between the atomic insulator limit and Landau level physics. Notably, many-body exact diagonalization reveals that the non-Abelian state can appear in the half-filled first Chern band. This construction can be further generalized to realize flat Chern bands analogous to higher Landau levels. Our results provide a new perspective on lattice analogs of Landau levels and may enable the exploration of fascinating topological phenomena at elevated temperatures.