We derive a Margolus-Levitin-type bound on the minimal evolution time of an arbitrarily driven open quantum system. We express this quantum speed limit time in terms of the operator norm of the nonunitary generator of the dynamics. We apply these results to the damped Jaynes-Cummings model and demonstrate that the corresponding bound is tight. We further show that non-Markovian effects can speed up quantum evolution and therefore lead to a smaller quantum speed limit time.

To induce transport, detailed balance must be broken. A common mechanism is to bias the dynamics with a thermodynamic fuel, such as chemical energy. An intriguing, alternative strategy is for a Maxwell demon to effect the bias using feedback. We demonstrate that these two different mechanisms lead to distinct thermodynamics by contrasting a chemical motor and information motor with identical dynamics. To clarify this difference, we study both models within one unified framework, highlighting the role of the interaction between the demon and the motor. This analysis elucidates the manner in which information is incorporated into a physical system.

We propose a new probe of the dependence of the fine-structure constant $\alpha$ on a strong gravitational field using metal lines in the spectra of white-dwarf stars. Comparison of laboratory spectra with far-UV astronomical spectra from the white-dwarf star G191-B2B recorded by the Hubble Space Telescope Imaging Spectrograph gives limits of $\Delta \alpha /\alpha =(4.2\pm 1.6)\times {10}^{-5}$ and $(-6.1\pm 5.8)\times {10}^{-5}$ from FeV and NiV spectra, respectively, at a dimensionless gravitational potential relative to Earth of $\Delta \varphi \approx 5\times {10}^{-5}$. With better determinations of the laboratory wavelengths of the lines employed these results could be improved by up to 2 orders of magnitude.

The TOTEM collaboration has measured the proton-proton total cross section at $\sqrt{s}=8\mathrm{TeV}$ using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been inserted very close to the beam allowing the detection of $\sim 90\%$ of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of $(101.7\pm 2.9)\mathrm{mb}$ has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: ${\sigma }_{\mathrm{el}}=(27.1\pm 1.4)\mathrm{mb}$; ${\sigma }_{\mathrm{inel}}=(74.7\pm 1.7)\mathrm{mb}$.

We calculate the bremsstrahlung photon spectrum emitted from dynamically evolving “quarkyonic” matter and compare this spectrum with that of a high chemical potential quark-gluon plasma as well as to a hadron gas. We find that the transverse momentum distribution and the harmonic coefficient is markedly different in the three cases. The transverse momentum distribution of quarkyonic matter can be fit with an exponential but is markedly steeper than the distribution expected for the quark-gluon plasma or a hadron gas, even at the lower temperatures expected in the critical point region. The quarkyonic elliptic flow coefficient fluctuates randomly from event to event and within the same event at different transverse momenta. The latter effect, which can be explained by the shape of quark wave functions within quarkyonic matter, might be considered as a quarkyonic matter signature, provided that the initial temperature is low enough that the quarkyonic regime dominates over deconfinement effects and the reaction-plane flow can be separated from the fluctuating component.

A new quantum Monte Carlo approach is proposed to investigate low-lying states of nuclei within the shell model. The formalism relies on a variational symmetry-restored wave function to guide the underlying Brownian motion. Sign or phase problems that usually plague quantum Monte Carlo fermionic simulations are controlled by constraining stochastic paths through a fixed-node-like approximation. Exploratory results in the $sd$ and $pf$ valence spaces with realistic effective interactions are presented. They prove the ability of the scheme to yield nearly exact yrast spectroscopies for both even- and odd-mass nuclei.

We address the partial wetting of liquid drops on ultrathin solid sheets resting on a deformable foundation. Considering the membrane limit of sheets that can relax compression through wrinkling at negligible energetic cost, we revisit the classical theory for the contact of liquid drops on solids. Our calculations and experiments show that the liquid-solid-vapor contact angle is modified from the Young angle, even though the elastic bulk modulus ($E$) of the sheet is so large that the ratio between the surface tension $\gamma$ and $E$ is of molecular size. This finding indicates a new elastocapillary phenomenon that stems from the high bendability of very thin elastic sheets rather than from material softness. We also show that the size of the wrinkle pattern that emerges in the sheet is fully predictable, thus resolving a puzzle in modeling “drop-on-a-floating-sheet” experiments and enabling a quantitative, calibration-free use of this setup for the metrology of ultrathin films.

Convective motions in a fluid layer are affected by its orientation with respect to the gravitational field. We investigate the long-term stability of a thermally stressed layer of a binary liquid mixture and show that pattern formation is strongly affected by marginal inclinations as small as a few milliradians. At small Rayleigh numbers, the mass transfer is dominated by the induced large scale shear flow, while at larger Rayleigh numbers, it is dominated by solutal convection. At the transition, the balance between the solutal and shear flows gives rise to drifting columnar flows moving in opposite directions along parallel lanes in a superhighway configuration.

The results of a self-consistent kinetic model of heating the solar corona and accelerating the fast solar wind are presented for plasma flowing in a nonuniform magnetic field configuration of near-Sun conditions. The model is based on a scale separation between the large transit or inhomogeneity scales and the small dissipation scales. The macroscale instability of the marginally stable particle distribution function compliments the resonant frequency sweeping dissipation of transient Alfvén waves by their induced emission in inhomogeneous streaming plasma that provides enough energy for keeping the plasma temperature decaying not faster than $r^{-1}$ in close agreement with in situ heliospheric observations.

The generation of dc magnetic fields in unmagnetized electron-ion shear flows is shown to be associated to either initial thermal effects or the onset of electron-scale shear instabilities, in particular the cold Kelvin-Helmholtz instability. This mechanism, intrinsic to shear gradients on the electron scale, is described through a kinetic model that predicts the growth and the saturation of the dc field in both scenarios. The theoretical results are confirmed by multidimensional particle-in-cell simulations, demonstrating the formation of long-lived magnetic fields ($t\sim 100’\mathrm{s}{\omega }_{pi}^{-1}$) along the full longitudinal extent of the shear layer, with a typical transverse width of $\sqrt{{\gamma }_0}c/{\omega }_{pe}$, reaching magnitudes $e{B}_{\mathrm{dc}}/m_{e}c{\omega }_{pe}\sim {\beta }_0\sqrt{{\gamma }_0}$ for an initial sharp shear. The case of an initial smooth shear is also discussed.

Runaway ions can be produced in plasmas with large electric fields, where the accelerating electric force is augmented by the low mean ionic charge due to the imbalance between the number of electrons and ions. Here we derive an expression for the high-energy tail of the ion distribution function in lightning discharges and investigate the energy range that the ions can reach. We also estimate the corresponding energetic proton and neutron production due to fusion reactions.

Interstitial loop coarsening by Ostwald ripening can provide insight into single point defects but is very difficult to observe in $\alpha$-iron and many other metals where nanoscale vacancy clusters dissociate and annihilate loops. We show that by implanting helium in the samples at a carefully chosen energy, it is possible to observe Ostwald ripening of loops by transmission electron microscopy during in situ isochronal annealings. This coarsening of loops results in a sharp increase of the mean loop radius at around 850 K. Using cluster dynamics simulations, we demonstrate that loops evolve due to vacancy emission and that such experiments give a robust estimation of the sum of the formation and migration free energies of vacancies. In particular, our results are in good agreement with self-diffusion experiments and confirm that entropic contributions are large for the vacancy in $\alpha$-iron.

Normal incidence ion irradiation at elevated temperatures, when amorphization is prevented, induces novel nanoscale patterns of crystalline structures on elemental semiconductors by a reverse epitaxial growth mechanism: on Ge surfaces irradiation at temperatures above the recrystallization temperature of $250°\mathrm{C}$ leads to self-organized patterns of inverse pyramids. Checkerboard patterns with fourfold symmetry evolve on the Ge (100) surface, whereas on the Ge (111) surface, isotropic patterns with a sixfold symmetry emerge. After high-fluence irradiations, these patterns exhibit well-developed facets. A deterministic nonlinear continuum equation accounting for the effective surface currents due to an Ehrlich-Schwoebel barrier for diffusing vacancies reproduces remarkably well our experimental observations.

We investigate the competition between the spin-orbit interaction of itinerant electrons and their Kondo coupling with local moments densely distributed on the honeycomb lattice. We find that the model at half-filling displays a quantum phase transition between topological and Kondo insulators at a nonzero Kondo coupling. In the Kondo-screened case, tuning the electron concentration can lead to a new topological insulator phase. The results suggest that the heavy-fermion phase diagram contains a new regime with a competition among topological, Kondo-coherent and magnetic states, and that the regime may be especially relevant to Kondo lattice systems with $5d$-conduction electrons. Finally, we discuss the implications of our results in the context of the recent experiments on ${\mathrm{SmB}}_6$ implicating the surface states of a topological insulator, as well as the existing experiments on the phase transitions in ${\mathrm{SmB}}_6$ under pressure and in CeNiSn under chemical pressure.

We propose a design for molecular charge qubits based on $\pi$-conjugated block copolymers and determine their electronic structure as well as their vibrational active modes. By tuning the length of the oligomers, the tunnel coupling in the charge qubit and its decoherence properties due to molecular vibrations can be chemically engineered. Coherent oscillations result with quality factors of up to ${10}^4$ at room temperature. In turn, the molecular vibrational spectrum induces strong non-Markovian electronic effects which support the survival of quantum coherence.

Structural and magnetic chiralities are found to coexist in a small group of materials in which they produce intriguing phenomenologies such as the recently discovered Skyrmion phases. Here, we describe a previously unknown manifestation of this interplay in ${\mathrm{MnSb}}_2{\mathrm{O}}_6$, a trigonal oxide with a chiral crystal structure. Unlike all other known cases, the ${\mathrm{MnSb}}_2{\mathrm{O}}_6$ magnetic structure is based on corotating cycloids rather than helices. The coupling to the structural chirality is provided by a magnetic axial vector, related to the so-called vector chirality. We show that this unique arrangement is the magnetic ground state of the symmetric-exchange Hamiltonian, based on ab initio theoretical calculations of the Heisenberg exchange interactions, and is stabilized by out-of-plane anisotropy. ${\mathrm{MnSb}}_2{\mathrm{O}}_6$ is predicted to be multiferroic with a unique ferroelectric switching mechanism.

The structure and properties of the ferromagnet ${\mathrm{Tb}}_{1-x}{\mathrm{Dy}}_x{\mathrm{Fe}}_2$ are explored through the morphotropic phase boundary (MPB) separating ferroic phases of differing symmetry. Our synchrotron data support a first order structural transition, with a broadening MPB width at higher temperatures. The optimal point for magnetomechanical applications is not centered on the MPB but lies on the rhombohedral side, where the high striction of the rhombohedral majority phase combines with the softened anisotropy of the MPB. We compare our findings with single ion crystal field theory and with ferroelectric MPBs, where the controlling energies are different.

A high-resolution neutron spectroscopic technique is used to measure momentum-resolved magnon lifetimes in the prototypical two- and three-dimensional antiferromagnets ${\mathrm{Rb}}_2{\mathrm{MnF}}_4$ and ${\mathrm{MnF}}_2$, over the full Brillouin zone and a wide range of temperatures. We rederived theories of the lifetime resulting from magnon-magnon scattering, thereby broadening their applicability beyond asymptotically small regions of wave vector and temperature. Corresponding computations, combined with a small contribution reflecting collisions with domain boundaries, yield excellent quantitative agreement with the data. Comprehensive understanding of magnon lifetimes in simple antiferromagnets provides a solid foundation for current research on more complex magnets.

The dynamics of ${\mathrm{Li}}^{+}$ transport in polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imde mixtures are investigated by combining neutron spin-echo (NSE) and dielectric spectroscopy with molecular dynamics (MD) simulations. The results are summarized in a relaxation time map covering wide ranges of temperature and time. The temperature dependence of the dc conductivity and the dielectric $\alpha$ relaxation time is found to be identical, indicating a strong coupling between both. The relaxation times obtained from the NSE measurements at $0.05{\AA }^{-1}<q<0.2{\AA }^{-1}$ are of similar magnitude as the relaxation time of ${\mathrm{Li}}^{+}$ predicted by MD simulation. Our results suggest that the characteristic live times of the ions within the oxygen cages are mainly determined by the $\alpha$ relaxation that corresponds to local segmental motions of polymers, to a much lesser extent by the main chain relaxation, and not at all by the $\beta$ relaxation or other faster processes. It is the first time decisive experimental evidence for a microscopic picture of the Li ion transportation process is shown in which the PEO chain forms EO cages over several monomer units and the Li ion “jump” from cage to cage. The role of the backbone of the polymer is discussed and contributes signifcantly to the Li ion transportation process. Moreover, detailed characteristic length and time scales of the ${\mathrm{Li}}^{+}$ transport process in this polymer electrolyte are identified and interpreted.

We show that some important properties of subdiffusion of unknown origin (including ones of mixed origins) can be easily assessed when finding the “fundamental moment” of the corresponding random process, i.e., the one which is additive in time. In subordinated processes, the index of the fundamental moment is inherited from the parent process and its time dependence from the leading one. In models of a particle’s motion in disordered potentials, the index is governed by the structural part of the disorder while the time dependence is given by its energetic part.