Computing excitation spectra of quantum many-body systems is a promising avenue to demonstrate the practical utility of current noisy quantum devices, especially as we move toward the “megaquop” regime. For this task, here we introduce a tangent space excitation ansatz for quantum circuits, motivated by the quasiparticle picture of many-body systems and the structural similarity between quantum circuits and tensor networks. Increasing circuit depth by one layer to construct tangent space around the variational optimum of a parametrized quantum circuit, we show that massive low-energy single-particle states can be captured. Our ansatz relies on a distinct mechanism from that of the excitation ansatz in a matrix product state and projected entangled-pair state, and avoids intrinsic limitations of the latter. Comparing our approach with existing quantum excited-state algorithms, we find that with similar computational cost, both the number of excited states and accuracy are significantly improved. We demonstrate our ansatz in both one and two dimensions, and further show that this approach, implementable using the Hadamard test, is scalable and suitable for current quantum processors.

Physical Gottesman-Kitaev-Preskill (GKP) states are inherently noisy as ideal ones would require infinite energy. While this is typically considered as a deficiency to be actively corrected, this Letter demonstrates that imperfect GKP stabilizer states can be leveraged in order to apply non-Clifford gates using only linear optical elements. In particular, Gaussian operations on normalizable GKP states, combined with homodyne measurements, permit two key primitives: clean projection onto Pauli eigenstates in the normalizable GKP code space, thereby implementing Clifford gates with high fidelity; and probabilistic projection of unmeasured modes onto non-Pauli eigenstates. These results demonstrate that normalizable GKP stabilizer states combined with Gaussian operations provide a practical framework for computational universality within the measurement-based model of quantum computation in a realistic continuous-variable setting.

This Letter presents a novel cosmic-ray scattering experiment employing a resistive plate chamber muon tomography system. By introducing the scattering angle between incident and outgoing cosmic-ray tracks as a key observable, this approach enables simultaneous studies of secondary cosmic-ray composition and searching for new physics. During a 63-day campaign, 1.18 million cosmic ray scattering events were recorded and analyzed. By performing combined template fits to the observed angular distribution, particle abundances are measured—for example, resolving the electron component at $\sim 2\%$ precision. Furthermore, constraints are established on elastic muon–dark matter (DM) scattering cross sections for muonphilic dark matter. At the 95% confidence level, the limit reaches $1.61\times {10}^{-17}{\mathrm{cm}}^2$ for 1 GeV slow DM, demonstrating the sensitivity limit to light muon-coupled slow DM, in scenarios where a strongly interacting dark matter component is captured and thermalized within Earth, leading to large surface densities.

A new scheme for detecting wavelike dark matter (DM) using Rydberg atoms is proposed. Recent advances in trapping and manipulating Rydberg atoms make it possible to use Rydberg atoms trapped in optical tweezer arrays for DM detection. We propose to prepare a large ensemble of Rydberg atoms and to observe the excitations between Rydberg states by the DM-induced effective electric field. A scan over DM mass is enabled with the use of the Zeeman and diamagnetic shifts of energy levels under an applied external magnetic field. Taking dark-photon DM as an example, we demonstrate that our proposed experiment can have high enough sensitivity to probe previously unexplored regions of the parameter space of dark-photon coupling strengths and masses.

Although Rydberg atoms have shown promise for use in novel types of radio frequency (rf) receivers, they have generally not been considered phase sensitive without the use of closed-loop interferometry or auxiliary rf fields. Here, we show that the high coherency of a narrow-linewidth three-photon ladder excitation scheme unique to cesium atoms enables all-optical sensing of transient changes in rf phase within a room temperature vapor cell. The transient response on the probe laser’s transmission originates from phase-to-amplitude conversion via a disturbance of the coherency of the system in response to the phase shift of the rf field. We show that the amplitude and frequency of the oscillatory response provide information on the magnitude and direction of any rf field detuning. We demonstrate that the detuning sensitivity can be used to identify Doppler shifts in radar applications, by applying phase shifts embedded in rf pulses. The phase modulation within the radar pulse acts as a form of compression that facilitates the simultaneous detection of both target position and velocity.

We report the numerical observation of a far-from-equilibrium equation of state (EOS) in the Gross-Pitaevskii (GP) model. We first show that the momentum distribution of the turbulent cascade is well described by wave-turbulent kinetic theory in the appropriate limits. Calculating the energy and particle fluxes ${\mathrm{\Pi }}_{ϵ}(k)$ and ${\mathrm{\Pi }}_N(k)$, we show that the turbulent state possesses the hallmarks of a direct energy cascade. Building on this, we show that the GP model encodes a universal EOS in the form of a relationship between the turbulent cascade’s momentum distribution amplitude $n_0$ and the energy flux $\epsilon$ in the steady state. We find that in our regime of “mixed” turbulence—where both vortices and waves play a significant role—$n_0\propto {\epsilon }^{0.67(2)}$, a result that is not captured by any existing theory of turbulence but that agrees with a recent experimental measurement for large energy fluxes. Finally, we find that the concept of quasi-static thermodynamic processes between equilibrium states extends to far-from-equilibrium steady states.

Chiral charge density waves (CDWs) have attracted intense interest due to their exotic quantum properties, yet the microscopic origin of structural chirality emerging from correlated charge order remains elusive. Here, we reveal that the interlayer phases of CDW vectors, an overlooked degree of freedom, play a crucial role in driving chiral structural displacements in layered CDW materials. By explicitly incorporating the interlayer phases in first-principles calculations, we successfully obtained the chiral structure of the CDW phases of $A{\mathrm{V}}_3{\text{Sb}}_5$ ($A=\mathrm{K}$, Rb, and Cs) and $1{\mathrm{T}\text{−}\mathrm{TiSe}}_2$. The electronic and optical properties of the predicted chiral structures are consistent with experimental measurements of these materials in their CDW phases. We further predict that $1{\mathrm{T}\text{−}\mathrm{NbSe}}_2$ is a promising material candidate for realizing chiral CDW order. Beyond materials prediction, our theory reveals that the chiral CDW can be manipulated by electron filling. Our Letter opens new avenues for discovering, designing, and engineering chiral CDW materials.

We prove that the time required for sustained information scrambling in any Hamiltonian quantum system is universally at least logarithmic in the entanglement entropy of scrambled states. This addresses two foundational problems in nonequilibrium quantum dynamics. (1) It sets the earliest possible time for the applicability of equilibrium statistical mechanics in a quantum system coupled to a bath at a finite temperature. (2) It proves a version of the fast scrambling conjecture, originally motivated in models associated with black holes, as a fundamental property of quantum mechanics itself. Our result builds on a refinement of the energy-time uncertainty principle in terms of the infinite temperature spectral form factor in quantum chaos. We generalize this formulation to arbitrary initial states of the bath, including finite temperature states, by mapping Hamiltonian dynamics with any initial state to nonunitary dynamics at infinite temperature. A regularized spectral form factor emerges naturally from this procedure, whose decay is universally constrained by analyticity in complex time. This establishes an exact speed limit on information scrambling by the most general quantum mechanical Hamiltonian without any restrictions on locality or the nature of interactions.

We study the threshold of gravitational collapse in spherically symmetric spacetimes governed by the Einstein-Maxwell-Vlasov equations. We numerically construct solutions describing a collapsing distribution of charged matter that either forms a charged black hole or eventually disperses. We first consider a region of parameter space where the solutions at the threshold of black hole formation are stationary, horizonless shells. These solutions terminate at a critical point, with their charge-to-mass ratio approaching unity from below, and the instability timescale diverging. Beyond the critical point, we find a new region of parameter space where the threshold solution is an extremal black hole. We measure the scaling of the dynamical time period of the near threshold solutions and discuss how they are connected in the two regimes. If a similar picture to the one found here holds for known families of stationary solutions of rotating matter that approach the exterior of an extremal Kerr spacetime, they could provide a route to forming an extremal spinning black hole.

We obtain the spectra of codimension-2 horizon “edge” degrees of freedom for gravity and higher-spin gauge fields in de Sitter space and in the static Nariai spacetime, advancing previous Lorentzian and Euclidean analyses of one-loop thermodynamics. The edge spectra exhibit universal shift symmetries, revealing a novel symmetry-breaking structure in one-loop partition functions with a positive cosmological constant. For the graviton, these modes admit a geometric interpretation as fluctuations of the cosmic horizon, which also persists in the Nariai case.

When a photon traverses a cloud of atoms without scattering, how much time does it spend as an atomic excitation? To address this question, we used the cross-Kerr effect to weakly probe the degree of atomic excitation caused by a transmitted resonant “signal” photon by measuring the phase shift induced on a (separate, off-resonant) “probe” beam, postselected on cases when the signal photon is transmitted. The time integral of this observed phase shift, properly normalized and averaged over many runs in which the photon is detected after transmission, is the excitation time of interest, in a weak-valued sense. We measured mean atomic excitation times ranging from $(-0.82\pm 0.31){\tau }_0$ for the most narrow band pulse to $(0.54\pm 0.28){\tau }_0$ for the most broadband signal pulse, where ${\tau }_0$ is the non-post-selected excitation time, given by the scattering probability multiplied by the atomic lifetime ${\tau }_{\mathrm{sp}}$. Across a range of pulse durations and optical depths, our results are consistent with the recent theoretical prediction that the weak value of the atomic excitation time caused by a transmitted photon equals the group delay experienced by the light. Our experimental results show that negative times are not limited to describing the shift in the peak of a reshaped wave packet (as resulting from group delay), but they also provide the appropriate description of the weak-valued time the photon spends as an atomic excitation.

The extreme anisotropy of hyperbolic materials enables extreme wave confinement, but it is also associated with an inherent misalignment between phase and energy flow, which complicates device modeling and design. Here, we introduce a Minkowski-space approach to describe hyperbolic wave propagation, showing that this complexity is geometric rather than physical. By embedding anisotropy into an effective Lorentzian metric, we establish a rational design framework for hyperbolic interfaces and lenses, and analytically derive their transfer function and resolution limits, enabling ultralarge numerical apertures and deep subdiffraction focusing. We validate our theory with the design and full-wave modeling of a planar van der Waals polaritonic lens operating in the midinfrared frequency range.

Polydisperse colloidal spheres serve as valuable model systems for studying single-particle dynamics in liquids, glasses, and crystals. Particle size critically influences local structure and free volume, which governs dynamics. However, accurately determining individual particle diameters from imaging data remains challenging. We introduce a linear programming method to extract hard-core diameters from particles’ positions. The approach achieves sub-0.1% error using only a brief video sequence, is robust to image blurring, and requires no prior knowledge of mean particle size or size distributions. The method is validated through simulations and experimental video data across diverse polydisperse systems. When input positions are inaccurate, as in real experimental data, a correction based on systematic simulations can yield more accurate radii than the original positions. Additionally, it provides a novel approach to correct misidentified particles in image analysis.

Biological tissues are active materials whose nonequilibrium dynamics emerge from distinct cellular force-generating mechanisms. Using a two-dimensional active foam model, we compare the effects of traction forces and junctional tension fluctuations on confluent tissue dynamics. While these two modes of activity produce qualitatively different cell shapes, rearrangement statistics, and spatiotemporal correlations in fluid states, we find that the long-time cellular motion universally converges to persistent Brownian dynamics. This universal feature contrasts with the nonuniversal correlations between cell geometry, rearrangement rate, and fluidity, which depend sensitively on the underlying modes of active force. Our results demonstrate that persistent Brownian motion provides a minimal framework for describing tissue dynamics, while distinct active forces leave identifiable structural and dynamical signatures, thereby enabling inference of the dominant active force in fluid state tissues.

We propose a scalable and noise-resilient protocol for the detection of the entanglement transition in a projective version of the transverse-field Ising model. Entanglement transitions are experimentally difficult to observe due to the inherent randomness of projective measurements and noise in large-scale experimental settings. Our approach combines error correction algorithms with classical shadow tomography to overcome both problems. This allows for experimentally accessible upper and lower bounds on the entanglement transition without postselection or full state tomography. These bounds remain robust under noise and their sharpness is a measure of the noise rate.