Autonomous Maxwell's demon is a new type of information engine proposed by Mandal and Jarzynski [Proc. Natl. Acad. Sci. USA 109, 11641 (2012)], which can produce work by exploiting an information tape. Here, we show how stochastic resetting can notably enhance the performance of autonomous Maxwell's demons in two ways: the speed of reaching their functional states and the range of their effective work regions. We propose some design principles for this system using stochastic resetting. Firstly, one can drive any autonomous demon system to its functional periodic steady state at a fastest pace from any initial distribution through resetting the demon for a predetermined critical time and then stopping the reset. Secondly, we can make the system achieve a new functional state with a larger effective working region by keeping the reset on. We also discover a dual-function region in a new phase diagram of the demon with resetting, where the demon can remarkably produce work and erase information on the tape at the same time, apparently breaking the second law of thermodynamics. We resolve this paradox by deriving a modified Clausius inequality that includes the cost of resetting.

Continuum limits are a powerful tool in the study of many-body systems, yet their validity is often unclear when long-range interactions are present. In this paper, we rigorously address this issue and put forth an exact representation of long-range interacting lattices that separates the model into a term describing its continuous analog, the integral contribution, and a term that fully resolves the microstructure, the lattice contribution. For any system dimension, for any lattice, for any power-law interaction, and for linear, nonlinear, and multiatomic lattices, we show that the lattice contribution can be described by a differential operator based on the multidimensional generalization of the Riemann zeta function, namely, the Epstein zeta function. We employ our representation in Fourier space to solve the important problem of long-range interacting unconventional superconductors. We derive a generalized Bardeen-Cooper-Schrieffer gap equation and find emerging exotic phases in two-dimensional superconductors with topological phase transitions. Finally, we utilize nonequilibrium Higgs spectroscopy to analyze the impact of long-range interactions on the collective excitations of the condensate. We show that the interactions can be used to fine tune the Higgs mode's stability, ranging from exponential decay of the oscillation amplitude up to complete stabilization. By providing a unifying framework for long-range interactions on a lattice, both classical and quantum, our research can guide the search for exotic phases of matter across different fields.

Thermodynamic behavior of polymer chains out of equilibrium is a fundamental problem in both polymer physics and biological physics. By using molecular dynamics simulation, we discover a nonequilibrium mechanism that controls the conformation and dynamics of polar active polymer; i.e., head activity commands the overall chain activity, resulting in a re-entrant swelling of active chains and a nonmonotonic variation of the Flory exponent $\nu$. These intriguing phenomena are the result of two competing nonequilibrium effects arising from the head-controlled railway motion of the chain, i.e., dynamic chain rigidity and the curling of chain conformation characterized by the negative bond vector correlation. Moreover, we identify several generic dynamic features of polar active polymers, i.e., linear decay of the end-to-end vector correlation function, polymer-size-dependent crossover from ballistic to diffusive dynamics, and diffusion coefficients sensitive to head activity. A simple dynamics theory is proposed to faithfully explain these interesting dynamic phenomena. These sensitive structural and dynamical responses of active polymer to its head activity provide us a practical way to control active agents with applications in biomedical engineering.

We consider point particles moving inside spherical urns connected by cylindrical channels whose axes both lie along the horizontal direction. The microscopic dynamics differ from that of standard 3D billiards because of a kind of Maxwell's demon that mimics clogging in one of the two channels, when the number of particles flowing through it exceeds a fixed threshold. Nonequilibrium phase transitions, measured by an order parameter, arise. The coexistence of different phases and their stability, as well as the linear relationship between driving forces and currents, typical of the linear regime of irreversible thermodynamics, are obtained analytically within the proposed kinetic theory framework, and are confirmed with remarkable accuracy by numerical simulations. This purely deterministic dynamical system describes a kind of experimentally realizable Maxwell's demon, that may unveil strategies to obtain mass separation and stationary currents in a conservative particle model.

We consider a one-dimensional driven-dissipative exciton-polariton condensate under incoherent pump, described by the stochastic generalized Gross-Pitaevskii equation. It was shown that the condensate phase dynamics maps under some assumptions to the Kardar-Parisi-Zhang (KPZ) equation, and the temporal coherence of the condensate follows a stretched exponential decay characterized by KPZ universal exponents. In this paper, we determine the main mechanisms, which lead to the departure from the KPZ phase, and identify three possible other regimes: (i) a soliton-patterned regime at large interactions and weak noise, populated by localized structures analog to dark solitons; (ii) a vortex-disordered regime at high noise and weak interactions, dominated by point-like phase defects in space-time; and (iii) a defect-free reservoir-textured regime where the adiabatic approximation breaks down. We characterize each regime by the space-time maps, the first-order correlations, the momentum distribution and the density of topological defects. We thus obtain the phase diagram at varying noise, pump intensity and interaction strength. Our predictions are amenable to observation in state-of-art experiments with exciton-polaritons.

We use Monte Carlo simulations and tensor network methods to study a classical monomer-dimer model on the square lattice with a hole (monomer) fugacity $z$, an aligning dimer-dimer interaction $u$ that favors columnar order, and an attractive dimer-dimer interaction $v$ between two adjacent dimers that lie on the same principal axis of the lattice. The Monte Carlo simulations of finite size systems rely on our grand-canonical generalization of the dimer worm algorithm, while the tensor network computations are based on a uniform matrix product ansatz for the eigenvector of the row-to-row transfer matrix that work directly in the thermodynamic limit. The phase diagram has nematic, columnar order and fluid phases, and a nonzero temperature multicritical point at which all three meet. For any fixed $v/u<\infty$, we argue that this multicritical point continues to be located at a nonzero hole fugacity $z_{\mathrm{mc}}(v/u)>0$; our numerical results confirm this theoretical expectation but find that $z_{\mathrm{mc}}(v/u)\to 0$ very rapidly as $v/u\to \infty$. Our numerical results also confirm the theoretical expectation that the corresponding multicritical behavior is in the universality class of the four-state Potts multicritical point on critical line of the two-dimensional Ashkin-Teller model.

Past experiments [S. Depierreux et al., Phys. Rev. Lett. 102, 195005 (2009)] have exhibited the plasma-induced incoherence (PII) process and the reduced imprint in the multikilojoule regime when a thin low-density foam is disposed in front of a solid target. Complementary experiments have been designed to analyze the mechanisms involved, the important parameters, and the role of the optical smoothing in the case of the laser megajoule. Forward stimulated Brillouin scattering (FSBS) is identified as the dominant mechanism governing the angular spray of the laser. FSBS also increases the laser bandwidth and imparts levels of temporal and spatial incoherencies beyond the present capacities of the optical smoothing of the megajoule laser facilities. Such a PII beam becomes suitable to achieve the high degree of irradiation uniformity required to experiment high-convergence efficient direct-drive inertial confinement fusion configurations at the megajoule scale which would otherwise require major changes in the laser chains. By reducing backscattering losses and/or allowing less optically applied smoothing, PII could relax the constraints imposed on the laser system and open the road to an increase in the energy coupled to the target in indirect-drive experiments.

The coexistence in the low-temperature spin-conducting phases of the zigzag materials ${\mathrm{BaCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ and ${\mathrm{SrCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ of one-dimensional (1D) physics with important deviations from it is not well understood. The studies of this paper account for an important selection rule that follows from interchain spin states being coupled more strongly within the spin dynamical structure factor of such zigzag materials whenever they are connected by a specific symmetry operation of the underlying lattice. In the case of excited states, this symmetry operation is only a symmetry in spin space if $no$ electronic spin flip is performed within the generation of such states. The corresponding selective interchain couplings both protect the 1D physics and are behind important deviations from it concerning the enhancement of the spectral-weight intensity of $S^{zz}(k,\omega )$. Strong evidence is provided that this justifies, beyond interchain mean-field theory and in contrast to 1D physics, the experimental low-energy dominance in both zigzag materials of the longitudinal nuclear magnetic resonance relaxation rate term $1/T_1^{\parallel }$ for the whole magnetic field interval of the spin-conducting phases. To further understand the role of selective interchain couplings concerning their contradictory effects in protecting the 1D physics and controlling deviations from it, the physical-spins scattering processes behind the experimentally observed sharp peaks in the dynamic structure factor components are investigated. Indeed, the experimentally observed Bethe strings in $S^{+-}(k,\omega )$ cannot be expressed in terms of configurations of usual spinons. We find that the line shape at and near the sharp peaks of the spin dynamic structure factor experimentally observed in ${\mathrm{BaCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ and ${\mathrm{SrCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ is fully controlled by unbound-unbound and unbound-bound scattering of singlet pairs of physical spins $1/2$. Our results on both the role of selective interchain couplings in protecting the 1D physics and being behind deviations from it and on the dynamical properties being controlled by scattering of singlet pairs of physical spins $1/2$ open the door to a key advance in the understanding of the physics of the spin chains in ${\mathrm{BaCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ and ${\mathrm{SrCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$.

Coarse graining is a common imperfection of realistic quantum measurement, obstructing the direct observation of quantum features. Under highly coarse-grained measurement, we experimentally certify the continuous-variable nonclassicality of both Gaussian and non-Gaussian states. Remarkably, we find that this coarse-grained measurement outperforms the conventional fine-grained measurement for nonclassicality certification: it detects nonclassicality beyond the reach of the variance criterion, and furthermore, it exhibits stronger statistical significance than the high-order moments method. Our work demonstrates the usefulness of coarse-grained measurement by providing a reliable and efficient way of nonclassicality certification for quantum technologies.

Long-distance quantum communication will require the use of quantum repeaters to overcome the exponential attenuation of signal with distance. One class of such repeaters utilizes quantum error correction to overcome losses in the communication channel. Here we propose a strategy of using the bosonic Gottesman-Kitaev-Preskill (GKP) code in a two-way repeater architecture with multiplexing. The crucial feature of the GKP code that we make use of is the fact that GKP qubits easily admit deterministic two-qubit gates, hence allowing for multiplexing without the need for generating large cluster states as required in previous all-photonic architectures based on discrete-variable codes. Moreover, alleviating the need for such clique clusters entails that we are no longer limited to extraction of at most one end-to-end entangled pair from a single protocol run. In fact, thanks to the availability of the analog information generated during the measurements of the GKP qubits, we can design better entanglement swapping procedures in which we connect links based on their estimated quality. This enables us to use all the multiplexed links so that large number of links from a single protocol run can contribute to the generation of the end-to-end entanglement. We find that our architecture allows for high-rate end-to-end entanglement generation and is resilient to imperfections arising from finite squeezing in the GKP state preparation and homodyne detection inefficiency. In particular we show that long-distance quantum communication over more than 1000 km is possible even with less than 13 dB of GKP squeezing. We also quantify the number of GKP qubits needed for the implementation of our scheme and find that for good hardware parameters our scheme requires around ${10}^3-{10}^4$ GKP qubits per repeater per protocol run.

Controlling the domain arrangement in a ferroelectric material is the key to accessing its functional properties. However, when a ferroelectric thin film is inserted into a multilayer device architecture, conventional characterization techniques provide limited access to the buried distribution of polar states. Here we show that a combination of nondestructive remote probing by nonlinear optics and symmetry analysis allows the unique distinction of the polar orientations coexisting in tetragonal ferroelectric films. We quantify the volumetric ratio between in-plane and out-of-plane polarized domains, and we further illustrate that our approach incorporates the strain-induced changes to the nonlinear susceptibility tensor. We perform the experiment on $\mathrm{Pb}\left({\mathrm{Zr}}_{0.2}{\mathrm{Ti}}_{0.8}\right){\mathrm{O}}_3$ thin films, but the generality of the approach permits its extension to other ferroelectric materials.

Due to numerous limitations including restrictive qubit topologies, short coherence times, and prohibitively high noise floors, few quantum chemistry experiments performed on existing noisy intermediate-scale quantum hardware have achieved the high bar of chemical precision, namely energy errors to within 1.6 mHa of full configuration interaction. To have any hope of doing so, we must layer contemporary resource reduction techniques with best-in-class error mitigation methods; in particular, we combine the techniques of qubit tapering and the contextual subspace variational quantum eigensolver with several error mitigation strategies comprised of measurement-error mitigation, symmetry verification, zero-noise extrapolation, and dual-state purification. We benchmark these strategies across a suite of eight 27-qubit IBM Falcon series quantum processors, taking preparation of the HCl molecule's ground state as our testbed.

Bound states in continuum (BICs) are states of a system possessing significantly large lifetimes with applications across various branches of science. In this work, we propose an expedient protocol to engineer BICs using the Kerr nonlinearities of a system which otherwise has no BICs. The generation of BICs is a direct artifact of the nonlinearity and the associated expansion in the dimensionality of the system. In particular, we consider single- and two-mode anharmonic systems and provide a number of solutions apposite for the creation of BICs. The nonlinearity-induced BICs can be controlled by external drive. In close vicinity to the BIC, the steady state response of the system is immensely sensitive to perturbations in natural frequencies of the system, and we illustrate its propitious sensing potential in the context of experimentally realizable setups for both optical and magnetic nonlinearities.

An orbital current can be generated whenever an object has a translational degree of freedom and a rotational degree of freedom. In condensed matter physics, intra-atomic contributions to the transverse orbital transport, labeled the orbital Hall effect, rely on propagating wave packets that must consist of hybridized atomic orbitals. However, interatomic contributions have to be considered as well because they give rise to an alternative mechanism for generating orbital currents. As we show, even wave packets consisting purely of $s$ electrons can transport orbital angular momentum if they move on a cycloid trajectory. We introduce the kagome lattice with a single $s$ orbital per atom as the minimal model for the orbital Hall effect and observe the cycloid motion of the electrons in the surface states.

We derive a set of functionals for optimization towards an arbitrary cat state and demonstrate their application by optimizing the dynamics of a Kerr-nonlinear Hamiltonian with two-photon driving. The versatility of our framework allows us to adapt our functional towards optimization of maximally entangled cat states, applying it to a Jaynes-Cummings model. We identify the strategy of the obtained control fields and determine the quantum speed limit as a function of the cat state's excitation. Finally, we extend our optimization functionals to open quantum system dynamics and apply it to the Jaynes-Cummings model with decay on the oscillator. For strong dissipation and large cat radii, we find a change in the control strategy compared to the case without dissipation. Our results highlight the power of optimal control with functionals specifically crafted for complex physical tasks and the versatility of the quantum optimal control toolbox for practical applications in the quantum technologies.

Unique features of particle orbits produce novel signatures of gravitational observable phenomena and are quite useful in testing compact astrophysical objects in general relativity or modified theories of gravity. Here we observe a representative example that a static, spherically symmetric black hole solution with nonlinear electrodynamics admits static points at finite radial distance. Each static point thus produces a static sphere, on which a massive test particle can remain at rest at arbitrary latitudes with respect to an asymptotic static observer. As a result, the well-known static Dyson spheres can be implemented by such orbits. More interestingly, employing a topological argument, we disclose that stable and unstable static spheres (if they exist) always come in pairs in an asymptotically flat spacetime. In contrast to this, the counterpart naked singularity has one more stable static sphere than the unstable one. Our results have potential applications in testing black holes in standard Maxwell and nonlinear electrodynamics, as well as in uncovering the underlying astronomical observation effects in other gravitational theories beyond general relativity.