Coarse-grained models have played an important role in the study of the behavior of DNA at length scales beyond a few hundred base pairs. Traditionally, these models have relied on structurally featureless and sequence-independent approaches, such as the twistable wormlike chain. However, research over the past decade has highlighted the substantial impact of DNA sequence even at the kilobase pair scale. Several robust sequence-dependent models have emerged, capturing intricacies at the base pair-step level. Here we introduce an analytical framework for coarse-graining such models to lower resolution representations while preserving essential structural and dynamic features, enabling the efficient sampling of large molecules. When considering both rotational and translational degrees of freedom, coarse-graining is shown to yield excellent results up to about one helical repeat. For scenarios where the local stretch modulus is inconsequential, this range can be significantly increased by only considering the rotational degrees of freedom, which permits faithful coarse-grained representation up to several helical repeats. Rather than providing a fully parametrized model, we present the methodology and software necessary for mapping any base pair-step model to the desired level of coarse-graining. Finally, we provide application examples of our method, including estimates of the persistence length and effective torsional stiffness of DNA in a setup mimicking a freely orbiting tweezer, as well as simulations of helically curved DNA.

We confirm by using the Skyrme Hartree-Fock-Bogoliubov calculation that ${}^{164}\mathrm{Pb}$ is a possible heaviest $N=Z$ doubly magic nucleus whose lifetime is long enough to be measured on accelerator experiments. We estimate the proton-emission and alpha-decay half-lives of ${}^{164}\mathrm{Pb}$. The estimated proton-emission half-life ranges from $0.1\mathrm{ps}$ to $10\mathrm{ns}$, while the alpha decay can be safely neglected.

As a typical representative of covalent superconductors, $\mathrm{S}{\mathrm{H}}_3$ has emerged as a significant milestone in superconductivity history and has greatly sparked interest in compressed hydrogen-rich superconductors. Authors of previous studies on theoretical design of ternary chalcogen-hydrogen compounds (known as chalcohydrides) have mainly focused on intercalating molecular motifs into the interstitial sites of the structural lattice or substituting atoms in the $\mathrm{S}{\mathrm{H}}_3$ backbone. Given the low electronegativity and small radius, lithium (Li) is empowered to serve as an excellent electron donor that can effectively turn the crystal structure and modulate the superconducting behavior. Here, we introduce Li into binary chalcohydrides and investigate ternary Li-$M$-H ($M$ = S, Se, and Te) compounds using the state-of-the-art structure prediction method in conjunction with first-principles calculations. As a result, five stable stoichiometries, including $\mathrm{LiS}{\mathrm{H}}_7, \mathrm{L}{\mathrm{i}}_2\mathrm{S}{\mathrm{H}}_6$, LiSH, $\mathrm{L}{\mathrm{i}}_2\mathrm{SH}$, and $\mathrm{Li}{\mathrm{S}}_2\mathrm{H}$, are identified at 100–200 GPa. Notably, metallic $\mathrm{LiS}{\mathrm{H}}_7$ and $\mathrm{L}{\mathrm{i}}_2\mathrm{S}{\mathrm{H}}_6$ exhibit a layered structure where the covalent bond between sulfur and hydrogen breaks up and the hydrogen atoms are released to recombine into molecules confined into the interlayer. Furthermore, our electron-phonon simulations reveal that the estimated superconducting transition temperature ($T_c$) of $\mathrm{L}{\mathrm{i}}_2\mathrm{S}{\mathrm{H}}_6$ (46 K) is lower than that (77 K) of $\mathrm{L}{\mathrm{i}}_2\mathrm{Se}{\mathrm{H}}_6$ at 200 GPa, which contrasts with the general belief that the light-weight elemental compound (high Debye temperature) has higher superconductivity. Our results offer critical insights into designing high-temperature superconductors with layered structures among multinary hydrides.

Although carbon materials are known for their versatile structures and properties, a crystalline phase of carbon being both metallic and ferromagnetic is yet to be found. Here, using an organic molecular precursor 3,3-dimethyl-1-butene (${\mathrm{C}}_6{\mathrm{H}}_{12}$) and a comprehensive theoretical study, we have discovered a metastable crystalline carbon phase that is both metallic and ferromagnetic under ambient conditions. The new carbon structures, produced by stacking puckered layers of 4,6-membered rings, are found to exhibit exotic electronic, magnetic, and mechanical properties originating from a special $\mathrm{s}{\mathrm{p}}^2-\mathrm{s}{\mathrm{p}}^3$ bonding topology. These findings open the prospect of realizing the metallic and ferromagnetic carbon allotrope in practice.

We investigated the influence of subcycle driving fields on high-order harmonic generation (HHG), with a focus on driver's intrinsic chirp, carrier-envelope phase (CEP), and number of laser cycles. Our findings reveal that the center frequency of a laser pulse scales as ${\tau }^{-5/4}$ with pulse duration $\tau$, and that attochirp exhibits a similar dependence on pulse duration. Additionally, we identified CEP-specific trends in harmonic yield: it increases as ${\tau }^{5/4}$ for ${\varphi }_0=0^{\circ }$ and decreases as ${\tau }^{-4.1}$ for ${\varphi }_0=-{90}^{\circ }$. Although subcycle pulses can generate intense isolated attosecond pulses (IAPs), they also tend to produce higher attochirp and reduced cutoff energies. However, effective compensation for attochirp can mitigate these drawbacks, thereby increasing the capability of subcycle pulses to generate short-duration, high-intensity IAPs. These results offer valuable insights into HHG using subcycle pulses and have important implications for the advancement of ultrafast light sources and the understanding of ultrafast phenomena at the attosecond timescale.

A coupling between Earth's rotation and orbital angular momentum (OAM), known as the Sagnac effect, is observed in entangled neutrons produced using a spin-echo interferometer. After correction for instrument systematics the measured coupling is within 5% of theory, with an uncertainty of 7.2%. The OAM in our setup is transverse to the propagation direction and scales linearly with neutron wavelength (4–12.75 Å), so the Sagnac coupling can be varied without mechanically rotating the device, which avoids systematic errors present in previous experiments. The detected transverse OAM of our beam corresponds to $4098\pm 295\hslash {\AA }^{-1},{10}^5$ times lower than in the previous neutron experiments. This demonstrates the feasibility of using the Sagnac effect to definitively measure neutron OAM and paves the way towards a future observation of the quantum Sagnac effect.

We study active steering protocols for weakly measured qubits in the presence of error channels due to amplitude and phase noise. If the error rate is sufficiently small, the protocol approaches and stabilizes a predesignated pure target state with high fidelity and high purity, and thus implements autonomous state stabilization. We present numerical simulation results for one and two qubits, taking Andreev qubit circuits as an example. As a function of the error rate, a sharp threshold separates an error-correcting weak-damping regime from a strong-damping regime where the target state cannot be reached anymore. At the threshold, the purity gap closes.

We simulate quench dynamics of the Su-Schrieffer-Heeger (SSH) chain on IBM quantum computers, calculating the Rényi entanglement entropy, the twist order parameter, and the Berry phase. The latter two quantities can be deduced from a slow-twist operator defined in the Lieb-Schultz-Mattis theorem. The Rényi entropy is obtained using a recently developed randomized measurement scheme. The twist order parameter and the Berry phase are measured without the need for additional gates or ancilla qubits. We consider quench protocols in which a trivial initial state evolves dynamically in time under the topological SSH Hamiltonian in the fully dimerized limit (the flat-band limit). During these quenches, there are persistent and periodic oscillations in the time evolution of both entanglement entropy and twist order parameter. Through the implementation of error mitigation techniques using a global depolarizing ansatz and postselection, our simulations on the IBM devices yield results that closely match exact solutions.

We address the experimentally relevant situation, where a nonequilibrium state is created by injecting charge current into a chiral quantum Hall edge state. We show that the commonly accepted picture of the full equilibration of a nonequilibrium state at finite distances contradicts the charge-conservation requirement. We propose and solve the transmission line model that accounts for the local equilibration process and the charge- and energy-conserving dynamics of the collective mode. We find that the correction of the electron distribution function to its eventual equilibrium form scales down slowly as $1/\sqrt{L}$ at long distances $L$.

Nonreciprocal charge transport in solids, where resistance is different between rightward and leftward currents, is a key function of rectifying devices in modern electronics, as exemplified by $p\text{−}n$ semiconductor junctions. Recently, this was also demonstrated in noncentrosymmetric materials in magnetic fields since their band structure exhibits spin polarization coupled to the position of momentum space due to antisymmetric spin-orbit coupling. To enhance the magnitude of the nonreciprocal effect, it is essential to tune such spin-momentum coupling, which has been hampered in conventional materials owing to the difficulty in controlling the broken inversion symmetry built into the lattice and interfacial structures. Here, we report large nonreciprocal resistivity in the layered polar metal $\mathrm{BaMn}{X}_2$ ($X=\mathrm{Sb}$, Bi), where the spin-polarized Dirac dispersion depends on the in-plane polarization tunable by chemical substitution of the $X$ site. For $X=\mathrm{Sb}$ with a pair of single-type valleys, the nonreciprocal resistivity increases monotonically with decreasing temperature, while for $X=\mathrm{Bi}$ with multiple types of valleys it is reduced by about an order of magnitude and exhibits a peak at a low temperature. Theoretical calculations indicate that the nonreciprocal resistivity is sensitive not only to the spin-momentum (spin-valley) coupling but also to the Fermi energy and the Dirac dispersion. The observed significant variation of nonreciprocal transport in the same series of materials might be of great use in the design of junction-free rectifying devices and circuits.

Low-depth random circuit codes possess many desirable properties for quantum error correction but have so far only been analyzed in the code capacity setting where it is assumed that encoding gates and syndrome measurements are noiseless. In this work, we design a fault-tolerant distillation protocol for preparing encoded states of one-dimensional random circuit codes even when all gates and measurements are subject to noise. This is sufficient for fault-tolerant quantum memory since these encoded states can then be used as ancillas for Steane error correction. We show through numerical simulations that our protocol can correct erasure errors up to an error rate of $2\%$. In addition, we also extend results in the code capacity setting by developing a maximum likelihood marginal decoder for depolarizing noise similar to work by Darmawan et al. [Phys. Rev. Res. 6, 023055 (2024)]. As in their work, we formulate the decoding problem as a tensor network contraction and show how to contract the network efficiently by exploiting the low-depth structure. Replacing the tensor network with a so-called “tropical” tensor network, we also show how to perform minimum weight decoding. With these decoders, we are able to numerically estimate the depolarizing error threshold of finite-rate random circuit codes and show that this threshold closely matches the hashing bound even when the decoding is suboptimal.

Most tissue properties and biological processes in tissues are dependent on or are regulated by the local mechanical stresses: Examples are cell division and differentiation, or, at larger scales, tissue morphogensis. In this paper, we theoretically study the rheology of two-dimensional epithelial tissues described by a discrete vertexlike model of actively dividing cells. We use a general analytical coarse-grained continuum formulation, which allows for explicit calculation of the mechanical stresses and the cell size and shape in various geometries. We discuss two different scenarios, a tissue under an applied simple shear and a supported tissue on an oscillating substrate. We show that this model predicts most often a shear-thinning behavior under a constant shear rate and, in certain circumstances, a crossover from shear thickening at low shear rates to shear thinning at high shear rates. We give an analytical expression for the tissue response in an oscillating strain experiment in the linear regime and calculate it numerically in the nonlinear regime. When the tissue is supported by an oscillating substrate, it reorients depending on frequency and the Poisson ratio of the substrate. Reorientation can be gradual or sharp, depending on the tissue's reference perimeter and the substrate Poisson ratio and on frequency. We also show the existence of a tricritical point in the orientation phase space.

In this work, we report, for the first time, an implementation of fermionic auxiliary-field quantum Monte Carlo (AFQMC) using matrix product state (MPS) trial wavefunctions, dubbed MPS-AFQMC. Calculating overlaps between an MPS trial and arbitrary Slater determinants up to a multiplicative error, a crucial subroutine in MPS-AFQMC, is proven to be #P-hard. Nonetheless, we tested several promising heuristics in successfully improving fermionic phaseless AFQMC energies. We also proposed a way to evaluate local energy and force bias evaluations free of matrix product operators. This allows for larger basis set calculations without significant overhead. We showcase the utility of our approach on one- and two-dimensional hydrogen lattices, even when the MPS trial itself struggles to obtain high accuracy. Our work offers a new set of tools that can solve currently challenging electronic structure problems with future improvements.

We propose an imaging system and methodology for mapping soft-tissue samples in three dimensions, with micron-scale and isotropic spatial resolution, with low-concentrations as well as in the absence of heavy metal staining. We used hard x-ray phase-contrast imaging for the x-ray ability to nondestructively probe the internal structure of opaque specimens and for enhanced contrast obtained by exploiting phase effects, even in cases with reduced or absent staining agents. To demonstrate its applicability to soft-tissue specimens, we built a compact system that is easily deployable in a laboratory setting. The imaging system is based on a conventional rotating anode x-ray tube and a state-of-the-art custom-made radiation detector. The systems performance is quantitatively assessed on a calibration standard. Its potential for soft-tissue microscopy is demonstrated on two biological specimens and benchmarked against gold-standard synchrotron data. We believe that the approach proposed here can be valuable as a bridging imaging modality for intravital correlative light and electron microscopy and be applied across disciplines where the three-dimensional morphology of pristine-condition soft tissues is a key element of the investigation.

Numerical simulation of turbulent fluid dynamics needs to either parametrize turbulence—which introduces large uncertainties—or explicitly resolve the smallest scales—which is prohibitively expensive. Here, we provide evidence through analytic bounds and numerical studies that a potential quantum speedup can be achieved to simulate fluid dynamics using quantum computing. Specifically, we provide a lattice Boltzmann formulation of fluid dynamics for which we give evidence that low-order Carleman linearization is much more accurate than previously believed for these systems. This is achieved via a combination of reformulating the Navier-Stokes nonlinearity $(\mathit{u}·\mathbf{\nabla }\mathit{u})$ to lattice-Boltzmann nonlinearity $\left({\mathit{u}}^2\right)$ and accurately linearizing the dynamical equations, which effectively trades nonlinearity for additional degrees of freedom that add negligible expense in the quantum solver. Based on this, we apply a quantum algorithm for simulating the Carleman-linearized lattice Boltzmann equation and provide evidence that its cost scales logarithmically with system size compared with polynomial scaling in the best known classical algorithms. In this paper, we suggest that a quantum advantage may exist for simulating fluid dynamics, paving the way for simulating nonlinear multiscale transport phenomena in a wide range of disciplines using quantum computing.

Registers of trapped neutral atoms, excited to Rydberg states to induce strong long-distance interactions, are extensively studied for direct applications in quantum computing. Here we present a $CC\mathrm{\Phi }$ quantum phase gate protocol based on radio-frequency-induced Förster resonant interactions in the array of highly excited ${}^{87}\mathrm{Rb}$ atoms. The extreme controllability of interactions provided by rf field application enables high-fidelity and robust gate performance for a wide range of parameters of the atomic system, as well as it significantly facilitates the experimental implementation of the gate protocol. Taking into account finite Rydberg states lifetimes, we achieve an average theoretical gate fidelity of $99.27\%$ under room-temperature conditions (improved up to $99.65\%$ in a cryogenic environment), thus showing the protocol compatibility with modern quantum error correction techniques.