In this paper, we consider fluctuations in a three-stroke cycle based on quantum measurement. In the first stroke, the engine is fueled by a nonselective quantum measurement; in the second stroke, an appropriate unitary operation is applied to extract work; and finally, the working medium is thermalized to complete the cycle. This protocol is analogous to charging, then discharging, and finally thermalizing a quantum battery. Using the Kirkwood-Dirac quasiprobability, we derive equations that provide insights into the fluctuations of heat and work, and thus into the charging and discharging processes. We then propose a quantum circuit to measure the cumulants of work and heat using a qubit ancilla. Afterward, we derive important upper and lower bounds on fluctuations in heat; this is thanks to the way we decompose heat fluctuations and the Kadison-Schwarz inequality. We also show, for the first time, that the imaginary part of the second cumulant of work equals the linear response of an average work (to be defined in the main text) or the quantum cross entropy. We further introduce an operator whose average defines the battery capacity and whose variance quantifies the corresponding fluctuations of the battery capacity. Our analytical results are illustrated and discussed through representative examples. We believe that our study will, on the one hand, be useful for understanding fluctuations in energy extracted from and injected into quantum batteries based on quantum measurements and, on the other hand, contribute to the foundations of quantum thermodynamics. More generally, our results can be applied beyond the three-stroke cycle considered here, especially to quantum batteries subject to environmental noise and decoherence.

Quantum error correction promises a viable path to fault-tolerant computations, enabling exponential error suppression when the device's error rates remain below the protocol's threshold. However, this threshold strongly depends on the classical method used to decode the measurements of the syndrome. These classical algorithms traditionally only interpret binary data, ignoring valuable information contained in complete analog measurement data. We present the first large-scale experimental verification of soft decoding by implementing repetition codes up to distance 51 on superconducting hardware. Unlike previous demonstrations limited to small code distances, this extensive range allows us to confirm a fundamental improvement in the exponential scaling of error suppression rather than a mere constant-factor reduction in error rates. We observe a 25% increase in the threshold, which yields logical error rates up to 30 times lower than standard hard decoding. Analyzing the trade-off between information volume and decoding performance, we show that a single byte of information per measurement suffices to reach optimal decoding. This underscores the effectiveness and practicality of soft decoding on hardware, including in time-sensitive contexts such as real-time decoding.

We propose a generalization of the eigenstate thermalization hypothesis accountin g for the emergence of symmetry-breaking phases. It consists of two conditions that any system with a degenerate spectrum must fulfill in order to thermalize. The failure of each condition generates a different nonthermalizing scenario. One is due to the absence of chaos and may indicate that extra constants of motion are required to describe equilibrium states. The other one implies the existence of initial conditions evolving toward symmetry-breaking equilibrium states. If it spreads across an entire spectral region, then this region gives rise to a symmetry-breaking phase. We explore the applicability of this formalism by means of numerical experiments on a three-site Bose-Hubbard model with two noncommuting discrete symmetries.

A phase-space approach is used and benchmarked for the simulation of the continuous-time evolution of large registers of qubits. It is based on a statistical ensemble of independent mean-field trajectories, where mean field is introduced at the level of the qubits, substituting quantum fluctuations/correlations with classical ones. The approach only involves at worse a quadratic cost in the system size, allowing to simulate up to several thousands of qubits on a classical computer. It provides qualitatively accurate description of one-qubit observables’ evolutions, making it a useful reference in comparison to techniques limited to small qubit numbers. The predictive power is, however, less robust for multiqubit observables. We benchmark the method on the $k$-local transverse-field Ising model, considering a large variety of systems ranging from local to all-to-all interactions, and from weak to strong coupling regimes, with up to 2000 qubits. To showcase the versatility of the approach, simulations on two-dimensional and three-dimensional Ising models are also made.

The design and performance of a cryogenic buffer gas beam source with a load-lock system is presented. The third generation of advanced cold molecule electric dipole moment search (ACME III) uses this source to produce a beam of cold, slow thorium monoxide (ThO) molecules. A feature of the apparatus is the capability of replacing the ablation targets without interrupting the vacuum or cryogenic conditions, thus increasing the average signal in the eEDM search. The beam source produces $1.3\times {10}^{11}$ ground-state ThO molecules per pulse on average, with rotational temperature of $4.8\mathrm{K}$, molecular beam solid angle of $0.31\mathrm{sr}$, and forward velocity of $200\mathrm{m}{\mathrm{s}}^{-1}$, parameters that are consistent with the performance of a traditional source (without a load lock) requiring time-consuming thermal cycles for target replacement. Long-term yield improvement of $\sim 40\%$ is achieved when the load-lock system is employed to replace targets every two weeks.

We investigate state estimation in discrete-time quantum walks with a single absorbing boundary. Using a spectral approach, we obtain closed expressions for the escape probability as a function of the initial coin state and the boundary position, together with the corresponding classical Fisher information for a binary absorption readout. Comparison with the single-copy quantum Fisher information reveals a clear complementarity: near boundaries carry broad information about the polar (Bloch-sphere) angle of the coin state, whereas moderate or distant boundaries reveal phase-sensitive regions. Because a single boundary probes only one information direction, combining two boundary placements yields, generically, a full-rank Fisher matrix and tight joint Cramér-Rao bounds while retaining a binary measurement without mode-resolved tomography. We also discuss a restricted-readout photonic implementation in which an on-chip sink realizes the absorber, and we frame the resulting advantage as a potential reduction in measurement-setting and reconfiguration overhead for low-dimensional parameter estimation tasks in architectures where direct projective access to the coin is unavailable. Our results show that absorption in quantum walks defines an analytically tractable restricted-access primitive for coin-state estimation.

Recent progress has been made in capturing spectral features of electronic states of double-excitation character in time-dependent density functional theory (TDDFT) through a frequency-dependent kernel. While it might appear that this development is limited to the perturbative regime, we show that when used within response-reformulated TDDFT (RR-TDDFT), it accurately captures strong-field dynamics involving states of double-excitation character. More generally, this demonstrates how RR-TDDFT enables exchange-correlation functional developments in the response regime, which have so far been more successful than those in the nonlinear regime, to be exploited for nonperturbative dynamics, thus significantly broadening their range of applications.

The next generation of rare-event searches, such as those aimed at determining the nature of particle dark matter or measuring fundamental neutrino properties, will benefit from particle detectors with thresholds at the meV scale, $100–1000\times$ lower than currently available. Quantum parity detectors (QPDs) are a class of proposed quantum devices, extending recent work on superconducting qubit sensors, that exploit the fingerprints of single quasiparticle tunneling across a coherent weak link as their detection concept. As envisioned, phonons generated by particle interactions within a crystalline substrate cause an eventual quasiparticle cascade within a surface-patterned superconducting qubit element. This process alters the fundamental charge parity of the device in a binary manner, which can be used to deduce the initial properties of the energy deposition. This work lays out multiple resonator-coupled readout schemes depending on qubit architecture, provides an analytic formulation for reconstructing sensor energies, and details strategies for multiplexing large arrays of sensors. We further compute the sensitivity of QPDs and detail an R&D pathway to demonstrating sub-eV energy deposit thresholds.

We compute static ($\omega \to 0$) tidal Love numbers for scalar ($s=0$) and Dirac ($s=1/2$) perturbations of static acoustic black holes (ABHs) in $(3+1)$ and $(2+1)$ dimensions, respectively. By imposing horizon regularity condition and matching to the large-radius expansion, we extract the ratio between decaying and growing modes. It turns out that in $(3+1)$ dimensions the scalar Love number is generically nonzero for ABHs, while the Fermionic Love numbers follow a universal power-law form $F_{\ell m}^{\pm 1/2}=\pm 4^{-(\ell +1/2)}$. In $(2+1)$ dimensions, the scalar field exhibits a strange logarithmic structure, causing the Bosonic Love number to vanish for even $m$ but remain nontrivial for odd $m$. In contrast, the Fermionic Love number in this case retains a simple power-law form $F_m=4^{-m}$ and is generically nonzero. These results provide insights into tidal response in analog-gravity systems and highlight qualitative differences between integer- and half-integer-spin fields.

Topological states, known for their robustness against disorder, offer promising avenues for disorder-resistant devices. However, their intrinsic spatial confinement at interfaces imposes geometric constraints that limit the scalability of topological functionalities. Here, we propose a strategy to overcome this limitation by using double-zero-index media to expand topological interfaces. Although occupying finite space, these media are optically equivalent to infinitesimal points at their working frequencies, effectively altering the geometry of topological interfaces and breaking conventional bulk-edge correspondence. This strategy enables the spatial expansion of uniform topological states beyond their native interface, offering new possibilities for topological photonic devices. Validated by simulations and microwave experiments, our findings offer a universal framework to break the inherent dimensional limitations of topological states, with implications extending to general wave systems.

Frustrated spin-1/2 model with all-antiferromagnetic exchange on Shastry-Sutherland lattice (SSL) has been extensively explored, and in this work we study the quantum phase diagram of isotropic Heisenberg spin-$1/2$ model on the SSL with ferromagnetic exchange interactions along leg, and antiferromagnetic couplings along the diagonal bonds ($J$). Using density matrix renormalization group (DMRG) and exact diagonalization calculations, we identify four distinct ground-state (gs) phases for this frustrated spin-1/2 model: stripe $(\pi ,0)$, stripe $(0,\pi )$, ferromagnetic, and spiral-dimer phases. In the spiral-dimer phase the gs can exhibit dimer formation along the diagonal bonds with or without spins spiral along the $x$ axis or $y$ axis in different parameter regime and these states are connected through crossovers. There is a continuous transition between stripe with a long-range spin-spin correlations and spiral-dimer phase with a short-range correlations. An effective spin parameter is introduced to accurately determine the phase boundaries. Our DMRG results differ significantly from previous Schwinger boson mean-field theory predictions. The spiral phase occurs in a narrow range of the parameter space and shows short-range correlations in the system.

Tidal Love numbers (TLNs) characterize the response of compact objects to external tidal fields and vanish for classical Schwarzschild and Kerr black holes in general relativity. Nonvanishing TLNs therefore provide a potential observational window into beyond-classical physics. In this work, we present a unified and fully analytic study of the TLNs of three representative classes of regular black holes—the Bardeen black hole, the black hole with sub-Planckian curvature, and the black hole arising in asymptotically safe gravity—under scalar, vector, and axial gravitational perturbations. Employing a Green’s function method combined with systematic perturbative expansions, we show that TLNs of regular black holes are generically nonzero and exhibit strong model and mode dependence. In many cases, higher-order corrections develop logarithmic scale dependence, closely resembling renormalization-group running in quantum field theory and revealing a scale-dependent tidal response absent in classical black holes. Our analysis demonstrates that the internal structure of regular black holes, including de Sitter or Minkowski cores and quantum-gravity-inspired modifications, leaves distinct fingerprints in their tidal properties. These results provide a comparative theoretical benchmark for assessing regular black-hole models and establish a basis for future phenomenological and observational studies with gravitational-wave detectors.

Stacking geometry in multilayer graphene (MLG) provides an interesting degree of freedom to engineer its electronic structure near the Fermi level, wherein the linear bands in single layer graphene could retain or evolve into parabolic or flat bands. Using a tight-binding model, we carried out a detailed analytical analysis of the electronic band structures for arbitrarily stacked MLGs. We show that their low-energy band dispersions near the Fermi level may be deduced from its substacks in isolation. The analytical solutions of the momenta with zero eigenvalue for an AA stacking allow us to generalize the results of the zero-energy momenta for arbitrarily stacked MLGs. Moreover, we find that an interplay of parallel and rhombohedral stacking allows for flat band engineering and enhancement in arbitrarily stacked MLG. The existence of enhanced flat bands in our discussed arbitrarily stacked MLGs might offer another interesting platform for exploring the flat band physics and possible flat band properties, like superconductivity, in graphene systems beyond the twisted bilayer graphene and simpler stacking orders.

We examine the complementarity among coherence (visibility), predictability, and entanglement for qubit and qutrit systems subjected to noisy quantum channels. Using the system-path entanglement framework, analytical expressions for all three quantities are derived for two-, three-, and $n$-slit interferometric setups. The study first establishes the validity of the triality relation in ideal conditions and then investigates its behavior under amplitude and phase damping. We find that amplitude damping redistributes coherence and population imbalance without violating complementarity, while phase damping reduces coherence but leaves predictability unchanged. We further extend the study to non-Markovian amplitude damping, where environmental memory effects lead to nonmonotonic evolution and revivals of coherence and entanglement. These results demonstrate that the complementarity relation remains preserved even in open quantum systems, highlighting its robustness against decoherence for both Markovian and non-Markovian open-system dynamics and providing a unified analytical understanding of noisy quantum interferometry in low-dimensional systems.

We model a direct solid-state phase transition through a nucleation-and-growth process in which plates have simple, regular shapes—squares, cubes, or square-faced lamellae—and grow homothetically (self-similarly) until they either reach a randomly assigned maximum size or are stopped by impingement with previously formed plates. The reverse transformation is represented by the preferential disappearance of smaller plates, while larger plates are retained during an incomplete reversion. A subsequent direct transformation therefore produces a modified plate-size distribution—a memory effect that forms the main focus of this study. Building upon an earlier two-dimensional ($2\mathrm{D}$) formulation, we extend the model to cubes ($3\mathrm{D}$) and to lamellar plates ($3{\mathrm{D}}_L$) in order to examine how dimensionality affects transformation memory. We introduce a quantitative descriptor of memory, the size mass ratio and find that memory is robust in all geometries but overall stronger in $2\mathrm{D}$ than in $3\mathrm{D}$ or $3{\mathrm{D}}_L$. We provide growth snapshots, arrest-regrowth cycles, size distributions, and differential scanning calorimetry simulations, and we compute the Shannon size-entropy to quantify configurational diversity. Although motivated by the thermal memory effect in shape-memory alloys, the model more generally identifies a purely geometric mechanism for memory in first-order solid-solid transformations, highlighting the role of dimensionality and geometric blocking in controlling the strength of transformation memory.

The ultrafast nonlinear optical responses of materials are not just theoretical concepts, but they play a significant role in developing modern photonic and optoelectronic devices, including optical time crystals. However, conventional materials often display either weak optical nonlinearities or slow response in the nanosecond timescale, rendering them ineffective for single-shot femtosecond pulse. This limitation can be overcome by leveraging the ultrafast charge transfer that is less than or equal to the pulse width of the laser in a donor-acceptor material pair. However, the low charge-transfer rates limit their effectiveness in high-speed applications. Here, we synthesized titanium carbide MXene-${\mathrm{VS}}_2$ hybrids characterized by strong electronic coupling, resulting in a remarkable enhancement in the ultrafast third-order nonlinear optical responses, enabled by charge transfer in less than the pulse width. For instance, we obtained a third-order nonlinear optical absorption coefficient of $(150\pm 16)\times {10}^{-3}$ cm/GW and a self-focusing (positive) nonlinear refractive index of $(94\pm 9)\times {10}^{-6}{\mathrm{cm}}^2/\mathrm{GW}$ at 800 nm in the femtosecond domain, both exceeding control samples by more than an order of magnitude. These enhancements are attributed to efficient charge transfer within the hybrid structure, supported by first-principles calculations and Bader charge analysis. Our findings have led to the development of an ultrafast optical limiter, featuring an onset threshold as low as $0.60\pm 0.05\mathrm{mJ}/{\mathrm{cm}}^2$, with a differential limiting transmittance of $0.46\pm 0.02$. These parameters are better than or comparable to the known benchmarks for high-speed nonlinear optical applications, demonstrating the potential for advanced photonic and optoelectronic devices.

An incommensurate charge density wave (CDW) is a periodic modulation of charge that breaks translational symmetry incongruently with the underlying lattice. Its low-energy excitations, the phasons, are collective, gapless phase fluctuations. We study a half-filled, four-band ladder model where a shift $\delta =p/q$ between the legs leads to a supercell of $q$ composite cells. The moiré potential narrows minibands near the Fermi level, resulting in additional peaks in the density of states, whose separation is controlled by $\delta$. The inclusion of short-range Coulomb interactions leads to an excitonic incommensurate CDW state. We identify the oscillations in its amplitude with a gapped Higgs collective mode and a lowest-energy Goldstone mode, realized by long-lived neutral phasons whose propagation velocity is governed by the shift $\delta$ and the interleg tunneling amplitude. Our results show that even the slightest interlayer mismatches can strongly modify both charge-ordering patterns and low-energy bosonic excitations in layered materials, and suggest that the enigmatic CDW phase in the quasi-one-dimensional compound ${\mathrm{HfTe}}_3$ is excitonic in nature.