High-fidelity quantum gates are essential for scalable quantum computation. However, at short durations, short-timescale waveform distortions break the time-reflection symmetry of control pulses, preventing the precise closure of cyclic evolution. This mechanism renders conventional symmetric protocols intrinsically overconstrained. Conventional strategies typically rely on smoothing the pulse envelopes or embedding the interaction pulse within a longer qubit pulse to bypass short-timescale distortions, which inevitably leads to a persistent speed-fidelity trade-off. To overcome this limitation, we introduce a cyclic control strategy based on parameter-space expansion, which restores controllability by incorporating an additional degree of freedom. We experimentally demonstrate this approach in a superconducting controlled-z gate, achieving robust suppression of coherent errors without increasing gate duration, reducing the average coherent error from 0.27% to 0.12% across multiple two-qubit gates, as validated by cross-entropy benchmarking. Our results establish a general route to fast, high-fidelity cyclic quantum gates beyond the conventional speed-fidelity trade-off.

Bosonic codes constitute a promising route to fault-tolerant quantum computing. Existing Floquet protocols enable analytical construction of bosonic codes but typically rely on slow adiabatic ramps with thousands of driving periods. In this Letter, we circumvent this bottleneck by introducing an analytical and deterministic Floquet method that directly synthesizes arbitrary unitaries within a single period. The phase-space unitary ensembles generated by our approach reproduce the Haar-random statistics, enabling practical pseudorandom states in continuous-variable systems. We prepare various prototypical bosonic codes from vacuum and implement single-qubit logical gates with high fidelities using quantum lattice gates. By harnessing the full intrinsic nonlinearity of Josephson junctions, quantum lattice gates decompose quantum circuits into primitive operations for efficient continuous-variable quantum computing.

We implement a decoy-state quantum key distribution scheme using a telecom C-band single-emitter source. The decoy states are created by varying the optical excitation of the quantum emitter to modulate the photon-number distribution. We provide an analysis of our scheme based on existing security proofs, allowing the calculation of secret key rates, including finite key effects. This enables us to demonstrate, with a realistic single-photon source, positive secret key rates using our scheme over 227 km of optical fiber, equivalent to a loss tolerance one order of magnitude greater than nondecoy schemes. This Letter broadens the scope of single-photon sources in future quantum networks by enabling long-distance quantum key distribution with realistic levels of single-photon purity.

We have made measurements of the difference between the position angle (PA) on the sky and the polarization position angle (PPA) of radio sources using data from a combination of the Radio Fundamental Catalogue (RFC) across a range of frequencies between 2.7 and 15 GHz and Cosmic Lens All-Sky Survey (CLASS) which observes polarization at 8.4 GHz (X-band). For the 2111 sources with jet PAs measured in the X-band and a known redshift, the distribution is peaked at $\approx 0°$ as expected for no birefringence and it can be modeled by two populations: one which is a Gaussian with mean ${\mu }_{\beta }=(0.2\pm 1.0)°$ and standard deviation ${\sigma }_{\beta }=(14.7\pm 1.1)°$ and the other a uniform distribution of sources which are a fraction $f_{\beta }=0.72\pm 0.02$ of the total. Uncertainties in ${\mu }_{\beta }$ can be reduced to $\approx 0.6°$ by stacking measurements of the PA from other wavebands. We find that limits of $\approx 0.1°$ might be possible with a sample of $\sim {10}^5$ similarly selected sources and that this could provide a confirmation of recent claims of global birefringence made using the cosmic microwave background observations from the Planck satellite.

A search for $CP$ violation in the ${\overline{B}}^0\to {\overline{K}}^{*0}{\mu }^{+}{\mu }^{-}$ decay is performed using proton-proton collision data collected by the LHCb experiment during Run 1 and Run 2, corresponding to an integrated luminosity of $8.4{\mathrm{fb}}^{-1}$. The analysis exploits the full angular distribution of the decay, providing sensitivity to $CP$-violating effects in both vector and axial-vector contributions to this flavor-changing neutral-current process. The complex Wilson coefficients are determined within the weak effective theory through an unbinned maximum-likelihood fit to the angular observables, incorporating nonlocal hadronic amplitudes across the full dimuon mass spectrum. The precision of the $CP$-violation observables is improved by an order of magnitude relative to previous measurements, with the imaginary parts of the Wilson coefficients now determined more precisely than the real parts. No significant $CP$ violation is observed, and the results are consistent with the standard model.

A quantum quasicrystal was proposed to exist by mean-field, variational arguments in two-dimensional Rashba spin-orbit coupled BECs with dipolar interactions. Despite this remarkable prediction, there is little known about the superfluid character or stability of this quasicrystalline state against thermal and quantum fluctuations, whose importance is implied by the massive single-particle degeneracy of the Rashba Hamiltonian. Here, we apply field-theoretic numerical simulations based on a boson coherent state path integral representation to simulate the finite-temperature behavior of a periodic approximant of an octagonal quasicrystal. We find that the quasicrystal state maintains a 50% superfluid fraction down to low temperature, suggesting supersolid character. We compute a phase diagram that depicts a region of thermodynamic stability for the octagonal quasicrystal phase at low temperature. At intermediate temperature, the quasicrystal undergoes a first-order transition into a crystalline BEC with hexagonal symmetry. Our findings support a possible experimental realization of the octagonal quasicrystal in ${}^{164}\mathrm{Dy}$ quantum gases below a temperature of 75 nK.

Three-level systems exhibit quantum interference effects absent in two-level systems, making them important for quantum optics. Here, we study the coherent interaction of a $\mathrm{\Lambda }$-type three-level system with free electrons shaped by optical near fields. By treating the electron train as a quantum drive, we show that the interplay between electron modulation and the three-level system’s transition pathways induces tunable interference patterns. This interaction effectively realizes electron-mediated coherent population trapping. We identify a regime that enables complete population transfer between the two lower states and the preparation of a high-coherence superposition, manifested as dark states. In particular, these driven-dissipative steady states are independent of the initial state. Our Letter proposes shaped free electrons as a platform for steady-state coherent control of three-level systems, enabling atomic-scale state engineering.

Density-corrected density functional theory (DC-DFT) considers whether self-consistent densities yield optimal energetics in Kohn-Sham calculations. With considerable success in molecular calculations, we here apply DC-DFT to solid-state calculations with Hartree-Fock (HF) densities. We resolve a known anomaly: that dispersion corrections can worsen results as one climbs Jacob’s ladder. This is illustrated for simple covalent solids, such as Si. The relative energetics of phases of ice are also much improved with HF densities, as is CO adsorption on NaCl, while graphite interlayer binding is insensitive to its density.

Fractional excitations provide a key to identifying sought-after topological quantum spin liquid states in realistic materials. Their single-particle dynamics already presents a challenging many-body problem on account of the coupling to their emergent gauge field. Here, we study the spinon excitations of kagome ice, realized at the $2/3$ magnetization plateau of spin ice, by combining up-to-63-site exact diagonalization with an analytical state graph mapping. We find a macroscopically degenerate mode in the spinon spectrum. It originates from the destructive interference due to the interaction with surrounding gauge fields, a form of many-body caging. We explicitly construct, and count, the concomitant many-body wave functions. Finally, we discuss the possible role of these flat modes in the magnetization process of kagome antiferromagnets, in particular with regard to the asymmetric termination of the kagome ice magnetization plateau.

We consider interacting paraparticle chains with a constant $R$ matrix where the Hamiltonian sums over the internal degrees (flavors) of the paraparticles. For such flavor-blind Hamiltonians, we show a general factorization of the Hilbert space into occupation and flavor parts with the Hamiltonian acting nontrivially only on the former. For open boundaries, the spectrum therefore coincides with that of the occupation Hamiltonian $H_{\mathrm{occ}}$ with the flavor part merely adding degeneracies. For periodic boundaries, a cyclic reordering of the flavors leads to a separation of $H_{\mathrm{occ}}$ into flux sectors at fixed particle number, thus making the parastatistics directly observable in the energy spectrum. For important exemplary cases, $H_{\mathrm{occ}}$ reduces to the XXZ chain with flux, allowing for an exact solution. In the gapless regime, this solution shows flux-shifted $c=1$ conformal towers in the low-energy spectrum and a temperature-dependent chemical potential in the bulk thermodynamics.

The time dynamics of flagellar and ciliary beating is often neglected in theories of microswimmers, with the most common models prescribing a time-constant actuation of the surrounding fluid. By explicitly introducing a metachronal wave, coarse-grained to a sinusoidal surface slip velocity, we show that a spatial resonance between the metachronal wave and the corrugation of a confining cylindrical channel enables a ciliate to swim even when it cannot move forward in a bulk fluid. Using lubrication theory, we reduce the problem to the Adler equation that reveals an oscillatory and steady swimming regime. Interestingly, a ciliate can even reverse its swimming direction in a corrugated channel compared to the bulk fluid.

Energy correlators have recently attracted significant attention in the study of heavy ion collisions due to their potential to robustly connect experimental measurements with an underlying quantum field theoretic description. While theoretical studies have so far primarily focused on the simplest two-point correlator, mapping out the dynamics of the quark-gluon plasma (QGP) will require developing a theoretical understanding of multipoint energy correlators. In this Letter, we present a systematic theoretical study of multipoint energy correlators for jets fragmenting in a dense quark-gluon plasma, accounting for both the medium’s perturbative modification to the jet and its hydrodynamical backreaction. We consider both the scaling behavior of projected correlators, as well as the shape dependent three-point correlator, highlighting how both provide insight into interactions with the QGP. We discuss the parametric dependence of modifications on the medium scales, opening new opportunities to experimentally separate jet modifications from the medium response. Our results open the door to a systematic exploration of multipoint energy correlators in heavy ion collisions.

We present the observation of three semiforbidden transitions in singly ionized ytterbium from the metastable ${}^2{\mathrm{F}}_{7/2}^o$ state. Owing to the long lifetimes of both the upper and lower states involved, these transitions are narrow and complement those already frequently used in this atom for quantum information and searches for new physics. We report the absolute frequencies of these electric quadrupole transitions, their isotope shifts, hyperfine structure, and measurements of the quadrupole transition moments. We find that the spontaneous lifetimes of these excited states are limited by slow magnetic dipole emission to lower-lying, odd-parity states, the lowest of which is accessible by laser excitation from ${{}^2\mathrm{F}}_{7/2}^o$ and is an attractive candidate for hosting a long-lived qubit.

We performed de Haas–van Alphen (dHvA) oscillation measurements and band-structure calculations for ${\text{YNi}}_2{\mathrm{B}}_2\mathrm{C}$. Our improved band structure successfully explained the origins of the large dHvA frequencies $\beta$ and $\zeta$, which were inexplicable in previous works. By comparing experimental effective masses with band masses, we determined the electron-phonon coupling for each orbit. The results showed a clear Fermi-surface-sheet dependence of the electron-phonon coupling strength, especially highlighting that the coupling for the band-28 sheet is very weak, almost absent for the orbit with $B\parallel c$. This finding is consistent with previous observations of dHvA oscillations from this orbit in the mixed state down to very low fields. Amid growing interest in high-temperature superconductivity driven by electron-phonon coupling in hydrides under high pressure, this Letter provides foundational data pivotal to precisely understanding electron-phonon coupling.

Kinetic uncertainty relations (KURs) set fundamental limits on the precision of nonequilibrium transport by bounding the signal-to-noise ratio of currents in terms of the dynamical activity, a quantity that counts exchange events between a system and its reservoirs. This framework is well established in the weak-coupling regime, where transport occurs via well-defined, particlelike tunneling processes. At strong coupling, however, quantum coherence challenges both the validity of standard KURs and the notion of activity itself. In this Letter, we introduce a generalized definition of dynamical activity valid at arbitrary system-reservoir coupling, and show that it leads to a breakdown of standard KURs at strong coupling. Building on this result, we derive and prove a novel uncertainty relation, denoted quantum KUR (QKUR), which provides a genuine quantum extension of KUR, accounting for intrinsic quantum coherent contributions of the generalized activity. We demonstrate that the generalized activity reduces to the standard master-equation definition in the weak-coupling regime for generic systems of $N$ coupled quantum dots described by a quadratic Hamiltonian, and analyze the resulting QKUR bound in paradigmatic quantum-coherent mesoscopic devices, including single- and double-quantum dot systems and a quantum point contact.

Active polymers are ubiquitous in nature, and often kicked by persistent noises that break detailed balance. In order to capture the out-of-equilibrium dynamics of such active polymers, we propose a simple yet reliable analytical framework based on a compounding formula. Connecting polymeric dynamics to the isolated monomeric behavior via the notion of tension propagation, the formula allows us to clarify rich scaling scenarios alongside corresponding intuitive physical pictures. We demonstrate distinctive transient and steady-state scalings due to the non-Markovian nature of the active noise. Aside from a paradigmatic example of an active Rouse polymer, we expect the framework to be applicable to wide variety of spatially extended systems, including more general polymers (crumpled globule, semiflexible polymers, etc.), fluctuation of growing interfaces, and an array of particles in single-file configuration.

Periodically driven quantum many-body systems exhibit a wide variety of exotic nonequilibrium phenomena and provide a promising pathway for quantum applications. A fundamental challenge for stabilizing and harnessing these highly entangled states of matter is system heating by energy absorption from the drive. Here, we propose and demonstrate a disorder-free mechanism, dubbed Fock space prethermalization (FSP), to suppress heating. This mechanism divides the Fock space network into linearly many sparse subnetworks, thereby prolonging the thermalization timescale even for initial states at high energy densities. Using 72 superconducting qubits, we observe an FSP-based time-crystalline order that persists over 120 cycles for generic initial Fock states. Further, we perform finite-size scaling analysis for domain wall (DW) and Fock space dynamics by varying system sizes, which reveals size-independent regimes for FSP-thermalization crossover and links the dynamical behaviors to the eigenstructure of the Floquet unitary. Our Letter establishes FSP as a robust mechanism for breaking ergodicity and paves the way for exploring novel nonequilibrium quantum matter and its applications.