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The study of dynamical phase transitions has been attracting considerable research efforts in the last decade. One theme of present interest is to search for exotic scenarios beyond the framework of equilibrium phase transitions. Here, we establish a duality between many-body dynamics and static Hamiltonian ground states for both classical and quantum systems. We construct frustration-free Hamiltonians whose ground-state phase transitions have rigorous duality to chaotic transitions in dynamical systems. By this duality, we show that the corresponding ground-state phase transitions are characterized by a bulk-to-surface response; these phase transitions are then dubbed “peratic,” meaning that they are defined by their response to the boundary. For the classical system, we show how the timelike dimension emerges in the static ground states. For the quantum system, the ground state is a superposition of geometrical lines on a two-dimensional array; these lines encode the dynamical Floquet evolution history of one-dimensional disordered spin chains. Our prediction of a peratic phase transition has direct consequences in quantum simulation platforms such as Rydberg atoms and superconducting qubits, as well as anisotropic spin glass materials. The discovery would shed light on the unification of dynamical phase transitions with equilibrium systems.

Under a general framework, shortcuts to adiabatic processes are shown to be possible in classical systems. We study the distribution function of the work done on a small system initially prepared at thermal equilibrium. We find that the work fluctuations can be significantly reduced via shortcuts to adiabatic processes. For example, in the classical case, probabilities of having very large or almost zero work values are suppressed. In the quantum case, negative work may be totally removed from the otherwise non-positive-definite work values. We also apply our findings to a micro Otto-cycle-based heat engine. It is shown that the use of shortcuts, which directly enhances the engine output power, can also increase the heat-engine efficiency substantially, in both quantum and classical regimes. [ABSTRACT FROM AUTHOR]

We demonstrate a general procedure to construct entanglement witnesses for any entangled state. This procedure is based on the trace inequality and a general form of entanglement witnesses, which is in the form W=ρ-cρI, where ρ is a density matrix, cρ is a non-negative number related to ρ, and I is the identity matrix. The general form of entanglement witnesses is deduced from Choi-Jamiolkowski isomorphism, that can be reinterpreted as that all quantum states can be obtained by a maximally quantum entangled state pass through certain completely positive maps. Furthermore, we provide the necessary and sufficient condition of the entanglement witness W=ρ-cρI in operation, as well as in theory. [ABSTRACT FROM AUTHOR]

Momentum accommodation is a key factor governing the transport of particles in gases from electric mobility and Brownian diffusion to thermophoresis. This paper explores the relationship between momentum accommodation of nanoparticles in dilute gases and surface adsorption. We demonstrate that the momentum accommodation factor is fundamentally equal to the probability of surface adsorption. Molecular dynamics simulations show that surface adsorption is the key mechanism behind the diffuse scattering model, and that upon gas-particle collision the immediate reflection dynamics and surface adsorption events are governed by the kinetic energy distribution of the rebounding gas molecules. This distribution determines the transition of the dominant mode of molecular scattering off a particle surface from diffuse to specular elastic reflection as the particle approaches the realm of molecular size. The kinetics and equilibrium of physisorption are examined to shed light on the effect of the lifetime of surface adsorbates on momentum transfer. A statistical treatment is proposed for the adsorption and hence the gas-nanoparticle momentum accommodation coefficient. The validity of the theoretical treatment is examined by comparing its prediction against experimental mobility data of silver nanoparticles. [ABSTRACT FROM AUTHOR]

The radiative transfer equation (RTE) has two asymptotic regimes characterized by the optical thickness, namely, optically thin and optically thick regimes. In the optically thin regime, a ballistic or kinetic transport is dominant. In the optically thick regime, energy transport is totally dominated by multiple collisions between photons; that is, the photons propagate by means of diffusion. To obtain convergent solutions to the RTE, conventional numerical schemes have a strong dependence on the number of spatial grids, which leads to a serious computational inefficiency in the regime where the diffusion is predominant. In this work, a discrete unified gas kinetic scheme (DUGKS) is developed to predict radiative heat transfer in participating media. Numerical performances of the DUGKS are compared in detail with conventional methods through three cases including one-dimensional transient radiative heat transfer, two-dimensional steady radiative heat transfer, and three-dimensional multiscale radiative heat transfer. Due to the asymptotic preserving property, the present method with relatively coarse grids gives accurate and reliable numerical solutions for large, small, and in-between values of optical thickness, and, especially in the optically thick regime, the DUGKS demonstrates a pronounced computational efficiency advantage over the conventional numerical models. In addition, the DUGKS has a promising potential in the study of multiscale radiative heat transfer inside the participating medium with a transition from optically thin to optically thick regimes. [ABSTRACT FROM AUTHOR]

Analytical expressions are derived for aerodynamic drag force on small cylinders in the free molecule flow using the gas-kinetic theory. The derivation considers the effect of intermolecular interactions between the cylinder and gas media. Two limiting collision models, specular and diffuse scattering, are investigated in two limiting cylinder orientations with respect to the drift velocity. The earlier solution of Dahneke [B. E. Dahneke, J. Aerosol Sci. 4, 147 (1973)] is shown to be a special case of the current expressions in the rigid-body limit of collision. Drag force expressions are obtained for cylinders that undergo Brownian rotation and for those that align with the drift velocity. The validity of the theoretical expressions is tested against experimental mobility data available for carbon nanotubes. [ABSTRACT FROM AUTHOR]

Long-lived and high-fidelity memory for a photonic polarization qubit (PPQ) is crucial for constructing quantum networks. We present a millisecond storage system based on electromagnetically induced transparency, in which a moderate magnetic field is applied on a cold-atom cloud to lift Zeeman degeneracy and, thus, the PPQ states are stored as two magnetic-field-insensitive spin waves. Especially, the influence of magnetic-field-sensitive spin waves on the storage performances is almost totally avoided. The measured average fidelities of the polarization states are 98.6% at 200 μs and 78.4% at 4.5 ms, respectively. [ABSTRACT FROM AUTHOR]

The light-matter quantum interface that can create quantum correlations or entanglement between a photon and one atomic collective excitation is a fundamental building block for a quantum repeater. The intrinsic limit is that the probability of preparing such nonclassical atom-photon correlations has to be kept low in order to suppress multiexcitation. To enhance this probability without introducing multiexcitation errors, a promising scheme is to apply multimode memories to the interface. Significant progress has been made in temporal, spectral, and spatial multiplexing memories, but the enhanced probability for generating the entangled atom-photon pair has not been experimentally realized. Here, by using six spin-wave-photon entanglement sources, a switching network, and feedforward control, we build a multiplexed light-matter interface and then demonstrate a ~sixfold (~fourfold) probability increase in generating entangled atom-photon (photon-photon) pairs. The measured compositive Bell parameter for the multiplexed interface is 2.49±0.03 combined with a memory lifetime of up to ~51 µs. [ABSTRACT FROM AUTHOR]