搜索结果：Physical review letters

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.

Laser cooling of atomic motion enables advances in quantum information and precision metrology. However, the spatial spreading of subrecoil-laser-cooled atoms-crucial for understanding cooling mechanisms and atomic confinement-remains largely unexplored. Here, we analyze anomalous diffusion in subrecoil-laser-cooled atoms, where a velocity-dependent fluorescence rate R(v)∝|v|^{α} governs transport properties. By tuning α, we uncover transitions between normal, subdiffusive, and superdiffusive regimes. Notably, at α=3/2, diffusion is minimized, leading to optimal atomic confinement. We further identify a conceptual link between subrecoil laser cooling and the Pomeau-Manneville map from nonlinear dynamics, revealing that anomalous diffusion can generically exhibit a nontrivial minimum in spatial spreading-even across seemingly unrelated physical systems.

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.

We analyze the 1D Anderson model with stealthy disorder, defined by a power spectrum that vanishes over a continuous band of wave numbers. Perturbative expansion of the self-energy and numerical results show that for small disorder W and prescribed stealthiness χ, the system is effectively delocalized, i.e., the localization length ξ exceeds large system sizes. This unusual behavior follows from the systematic cancellation of leading terms so that ξ scales as W^{-2n} with large n. Since the underlying mechanism depends only on the stealthy disorder, our findings also apply to photonic and phononic waves.

Computing topological invariants in two-dimensional quasicrystals and supermoiré matter is a remarkable open challenge due to the absence of translational symmetry and the colossal number of sites inherent to these systems. Here, we establish a method to compute local topological invariants of exceptionally large systems using tensor networks, enabling the computation of invariants for Hamiltonians with hundreds of millions of sites, several orders of magnitude above the capabilities of conventional methodologies. Our approach leverages a tensor network representation of the density matrix using a Chebyshev tensor network algorithm, enabling large-scale calculations of topological markers in quasicrystalline and moiré systems. We demonstrate our methodology with two-dimensional quasicrystals featuring C_{8} and C_{10} rotational symmetries and mosaics of Chern phases. Our Letter establishes a powerful method to compute topological phases in exceptionally large-scale topological systems, providing the required tool to rationalize generic super-moiré and quasicrystalline topological matter.

Understanding and controlling the seeding of hydrodynamic perturbations are crucial for achieving ignition and high gain in inertial confinement fusion (ICF). In this Letter, we present face-on radiography of planar foil with preimposed sinusoidal ripples, revealing a novel phenomenon that the perturbation inverts its phase during the acceleration of the ablation front. With radiation-hydrodynamic simulations and a simple model, we can identify a secular (nonexponential) growth dominated regime before the quasisteady acceleration of the foil is fully established. Further evaluation reveals another novel freeze-out-like phenomenon, in which the growth of the ablation front perturbation ceases for a substantial duration relative to the acceleration phase. Our results advance the understanding of the Rayleigh-Taylor seeding in ICF implosions and inspire new designs for high-gain ICF targets.

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.

We performed high-precision decay-pion spectroscopy of light Λ hypernuclei at the Mainz Microtron (MAMI) using the A1 spectrometer facility. By measuring the monochromatic π^{-} momentum from the two-body weak decay _{Λ}^{3}H→^{3}He+π^{-} and referencing it to the _{Λ}^{4}H→^{4}He+π^{-} decay, we determined the Λ binding energy of _{Λ}^{3}H with unprecedented accuracy. The obtained value, B_{Λ}(_{Λ}^{3}H)=0.523±0.013_{stat}±0.075_{syst}.  MeV, is consistent with the STAR result, but indicates a significantly deeper binding than inferred from earlier measurements. This result implies a stronger Λ-deuteron interaction and provides stringent constraints on hyperon-nucleon interactions.

The mean pairwise velocity of massive halos reflects the gravitational force law on cosmic scales. We combine cosmic microwave background intensity maps from the Atacama Cosmology Telescope and a galaxy catalog from the Sloan Digital Sky Survey to estimate the mean pairwise velocity using the kinematic Sunyaev-Zeldovich (kSZ) effect. On scales from 30 to 230 megaparsecs, we constrain the gravitational acceleration between pairs of halos at separation r to be g∝1/r^{n} with n=2.1±0.3, which is consistent with Newtonian gravity in an expanding spacetime (i.e., the standard ΛCDM model). This constraint shows agreement with an inverse quadratic radial dependence over the large distances separating galaxy halos, as expected in standard cosmology. Upcoming surveys have the potential to rule out n=1 at 10σ significance. Our results establish the kSZ effect as a powerful tool for testing gravity on cosmological scales.

Ion acceleration in Z-pinch plasmas is traditionally linked to the axial direction of current. Here, we report the radial emission of MeV protons from a low-mass, hydrogen-containing X pinch. Proton energies up to 3 MeV are observed in a hybrid X pinch with a 30  μm polyethylene fiber at a 400 kA peak current. The low-mass load, correlation of protons with hard x-rays, and timing of hard x-ray emission point to proton acceleration driven by current disruption following fiber disintegration. A new insight into the acceleration mechanism arises from the use of an interelectrode gap that is too short for magnetic fields to bend axially accelerated protons by π/2 radians; thus, the observed radial emission implies a substantial radial acceleration component. The radial emission also enables X-pinch-driven proton radiography, the exceptional potential of which is demonstrated with exploding wires.

We present a method characterizing thermal noise in an optical cavity independent from quantum noise despite the thermal noise falling below the quantum noise limit. Using this method, we measured the thermal noise contribution from a GaAs/AlGaAs micromirror suspended on a GaAs cantilever microresonator when brought to a cryogenic temperature (∼25  K) and incorporated into a Fabry-Pérot cavity. An optical spring is formed in this optical cavity. Previously, this setup exploited an optical spring to produce a displacement sensitivity falling 2.8 dB below the free-mass standard quantum limit (SQL), as reported by Cullen et al. [Phys. Rev. Lett. 133, 113602 (2024)PRLTAO0031-900710.1103/PhysRevLett.133.113602]. Here we use a similar setup to measure thermal noise which fell a maximum of 5 dB below the SQL. This measurement, in turn, allowed for an investigation of quantum noise suppression resulting from the optical spring effect, falling a maximum of 10 dB below the SQL, a new benchmark for sub-SQL optomechanical measurements.

We provide a new perspective on the cosmological constant by exploring the background-independent Wheeler-DeWitt quantization of general relativity. The Chern-Simons-Kodama state of quantum gravity, a generalization of the Hartle-Hawking and Vilenkin states, has a striking structural similarity to the topological field theory of the quantum Hall effect. As a result, we study the gravitational topological θ sectors in analogy to Yang-Mills theory. We find that the cosmological constant Λ is intimately linked to the θ parameter by θ=12π^{2}/(Λℓ_{Pl}^{2}) mod 2π due to the fact that Chern-Simons-Kodama state must live in a particular θ sector. This result is shown in the canonical, nonperturbative formalism. Furthermore, we explain how the physics of the Hamiltonian constraint is analogous to the quantum Hall effect, with the cosmological constant playing the role of a quantum gravitational Hall resistivity. These relations suggest that Λ is topologically protected against perturbative graviton loop corrections, analogous to the robustness of quantized Hall conductance against disorder in a metal.

Elastic disordered interfaces driven through a heterogenpeous landscape respond via intermittent avalanches. In the overdamped limit, avalanche sizes follow a scale-free power-law distribution. Here, we investigate how inertial and dynamical terms beyond the overdamped approximation modify this behavior, focusing on the combined effects of interaction range, dimensionality, and dissipation. Using large-scale numerical simulations, we show that these additional terms robustly generate system-spanning events-so-called kings-responsible for a characteristic bump in the avalanche size distribution, which arise only in the presence of dissipation. We identify two distinct mechanisms underlying this phenomenon. In two-dimensional systems with long-range elasticity, we observe genuine kings, which persist in the thermodynamic limit and are consistent with mean field predictions. In contrast, one-dimensional systems with long-range elasticity and systems with short-range interactions in both 1D and 2D exhibit ghost kings: failed synchronization events producing large, but finite, ballistically spreading avalanches. Our findings clarify the origin of bump features in avalanche statistics and establish the conditions under which true system-spanning events emerge in realistic, dissipative systems.

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.

Both the minimal size of optically switched magnetic bits and the wavelengths of optically excited spin waves in optomagnonic devices are fundamentally diffraction limited. Here, we propose and experimentally demonstrate a novel method to overcome these limitations by using a specially designed magnetophotonic waveguide structure. This structure enables the creation of a sign-changing profile of the inverse Faraday effect (IFE) induced in the magnetic film by the circularly polarized femtosecond laser pulse tuned to the resonance of the optical TE guided mode. The spatial period of the IFE profile is subdiffractive, which allows for the launch of narrow band exchange-dominated magnetostatic spin waves. As experimentally demonstrated, their wavelengths are around 300 nm, and they can potentially be reduced to 100 nm. This opens new horizons for optomagnetic applications, ranging from logic elements to data processing devices.

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.

Combining high-speed photography with direct force measurements, we investigate the impact dynamics of drops of cornstarch-water mixtures-a premier example of shear-thickening fluids-across a wide range of impact conditions. Our Letter identifies three distinct impact regimes. In addition to the liquidlike and solidlike behaviors generally expected for the impact-induced response of shear-thickening fluids, we uncover a counterintuitive regime in which high-concentration cornstarch-water mixtures display a liquidlike response at the onset of impact when shear rates are high and only transition to a solidlike behavior at later times as shear rates reduce. By integrating the classic drop-impact theory with the Reynolds-Darcy mechanism for dilatancy, we develop a unified model that quantitatively describes the impact dynamics of shear-thickening drops across all regimes. Our Letter reveals the unexpected response of shear-thickening fluids to ultrafast deformation and advances the fundamental understanding of drop impact for complex fluids.

The lifetime of the J^{π}=2^{+} state in the self-conjugate ^{88}Ru nucleus has been determined in an experiment performed using rare-isotope beams provided by the new Facility for Rare Isotope Beams. This is the heaviest N=Z nucleus for which such a measurement has been achieved. ^{88}Ru was populated by both one-neutron knockout and charge-exchange reactions, and the lifetime of 14.3_{-3.4}^{+2.5}  ps was determined using the triple-foil plunger technique. The extracted electromagnetic transition strength shows that the quadrupole collectivity has dropped significantly compared with the highly deformed N=Z region around A∼80. These results are compared with state-of-the-art large-scale shell-model and discrete nonorthogonal shell-model calculations. The theoretical calculations indicate a moderate triaxial deformation and suggest that low-lying states in this nucleus are no longer dominated by strong many-particle many-hole excitations, unlike the lighter, highly deformed N=Z nuclei nearby.

High precision measurements are essential to solve major scientific and technological challenges, from gravitational wave detection to healthcare diagnostics. Quantum sensing delivers greater precision, but an in-depth optimization of measurement procedures has been overlooked. Here, we present a systematic strategy for parameter estimation in the low-data limit that integrates experimental control parameters and natural symmetries. The method is guided by a Bayesian quantifier of precision gain, enabling adaptive optimization tailored to the experiment. We provide general expressions for optimal estimators for any parameter. The strategy's power is demonstrated in a quantum technology experiment, in which ultracold caesium atoms are confined in a micromachined hole in an optical fiber. We find a fivefold reduction in the fractional variance of the estimated parameter, compared to the standard measurement procedure. Equivalently, our strategy achieves a target precision with a third of the data points previously required. Such enhanced device performance and accelerated data collection will be essential for applications in quantum computing, communication, metrology, and the wider quantum technology sector.