Based on results from a measurement of weak decay branches observed following the ${\beta }^{-}$ decay of ${}^{94}\mathrm{Y}$ and on lifetime data from a study of ${}^{94}\mathrm{Zr}$ by inelastic neutron scattering, collective structure is deduced in the closed-subshell nucleus ${}^{94}\mathrm{Zr}$. These results establish shape coexistence in ${}^{94}\mathrm{Zr}$. The role of subshells for nuclear collectivity is suggested to be important.

Strong field single ionization of homo- and heteronuclear noble gas dimers with ultrashort infrared laser pulses is experimentally investigated. A pronounced photoelectron yield maximum is found for dimers in the momentum range $|\mathbf{p}|\le 0.1\mathrm{a}.\mathrm{u}.$ which is absent for the corresponding monomer. This yield enhancement can be attributed to a new two-step strong field ionization mechanism active only in the dimers. In the first step, frustrated tunnel ionization at one of the atomic centers populates Rydberg states, which then become ionized in a second step through charge oscillation within the dimer ion core.

The generation of astrophysically relevant jets, from magnetically collimated, laser-produced plasmas, is investigated through three-dimensional, magnetohydrodynamic simulations. We show that for laser intensities $I\sim {10}^{12}–{10}^{14}\mathrm{W}\mathrm{c}{\mathrm{m}}^{-2}$, a magnetic field in excess of $\sim 0.1\mathrm{MG}$, can collimate the plasma plume into a prolate cavity bounded by a shock envelope with a standing conical shock at its tip, which recollimates the flow into a supermagnetosonic jet beam. This mechanism is equivalent to astrophysical models of hydrodynamic inertial collimation, where an isotropic wind is focused into a jet by a confining circumstellar toruslike envelope. The results suggest an alternative mechanism for a large-scale magnetic field to produce jets from wide-angle winds.

We create and study persistent currents in a toroidal two-component Bose gas, consisting of ${}^{87}\mathrm{Rb}$ atoms in two different spin states. For a large spin-population imbalance we observe supercurrents persisting for over two minutes. However, we find that the supercurrent is unstable for spin polarization below a well-defined critical value. We also investigate the role of phase coherence between the two spin components and show that only the magnitude of the spin-polarization vector, rather than its orientation in spin space, is relevant for supercurrent stability.

By transforming heat flux from particle to wave phonon transport, we introduce a new class of engineered material to control thermal conduction. We show that rationally designed nanostructured alloys can lead to a fundamental new approach for thermal management, guiding heat as photonic and phononic crystals guide light and sound, respectively. Novel applications for these materials include heat waveguides, thermal lattices, heat imaging, thermo-optics, thermal diodes, and thermal cloaking.

The recent discovery of phase IV of solid hydrogen and deuterium consisting of two alternate layers of graphenelike three-molecule rings and unbound ${\mathrm{H}}_2$ molecules have generated great interest. However, the vibrational nature of phase IV remains poorly understood. Here, we report a peculiar proton or deuteron transfer and a simultaneous rotation of three-molecule rings in graphenelike layers predicted by ab initio variable-cell molecular dynamics simulations for phase IV of solid hydrogen and deuterium at pressure ranges of 250–350 GPa and temperature range of 300–500 K. This proton or deuteron transfer is intimately related to the particular elongation of molecules in graphenelike layers, and it becomes more pronounced with increasing pressure at the course of larger elongation of molecules. As the consequence of proton transfer, hydrogen molecules in graphenelike layers are short lived and hydrogen vibration is strongly anharmonic. Our findings provide direct explanations on the observed abrupt increase of Raman width at the formation of phase IV and its large increase with pressure.

Ab initio simulations are combined with in situ infrared spectroscopy to unveil the molecular transport of ${\mathrm{H}}_2$, ${\mathrm{CO}}_2$, and ${\mathrm{H}}_2\mathrm{O}$ in the metal organic framework MOF-74-Mg. Our study uncovers—at the atomistic level—the major factors governing the transport mechanism of these small molecules. In particular, we identify four key diffusion mechanisms and calculate the corresponding diffusion barriers, which are nicely confirmed by time-resolved infrared experiments. We also answer a long-standing question about the existence of secondary adsorption sites for the guest molecules, and we show how those sites affect the macroscopic diffusion properties. Our findings are important to gain a fundamental understanding of the diffusion processes in these nanoporous materials, with direct implications for the usability of MOFs in gas sequestration and storage applications.

The early spreading of a liquid drop on a solid surface driven by inertial, capillary, and electrostatic forces is of fundamental interest, since most commonly used surfaces are (naturally) charged. We studied the effect of applying an electric potential between a drop and a surface on the early spreading of aqueous electrolyte drops. We found that spreading dynamics not only depended on the potential, but also on the electrolyte concentration. Based on molecular dynamics simulations of the ion distribution in spreading nanodrops under an applied potential, we propose a simple model to explain the relation between applied potential, electrolyte concentration, and early spreading dynamics.

We propose a microscopic physical mechanism that stabilizes the coexistence of the Kondo effect and antiferromagnetism in heavy-fermion systems. We consider a two-dimensional quantum Kondo-Heisenberg lattice model and show that long-range electron hopping leads to a robust antiferromagnetic Kondo state. By using a modified slave-boson mean-field approach we analyze the stability of the heavy antiferromagnetic phase across a range of parameters, and discuss transitions between different phases. Our results may be used to guide future experiments on heavy fermion compounds.

A ${}^{125}\mathrm{Te}$ NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from $p$-band carriers. Whereas nanocrystals follow a Korringa law in the range 140–420 K, micrometer particles do so only below 200 K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.

Inelastic electron tunneling spectroscopy is a powerful spectroscopy that allows one to investigate the nature of local excitations and energy transfer in the system of interest. We study inelastic electron tunneling spectroscopy for topological insulators and investigate the role of inelastic scattering on the Dirac node states on the surface of topological insulators. Local inelastic scattering is shown to significantly modify the Dirac node spectrum. In the weak coupling limit, peaks and steps are induced in second derivative $d^{2}I/d{V}^2$. In the strong coupling limit, the local negative-$U$ centers are formed at impurity sites, and the Dirac cone structure is fully destroyed locally. At intermediate coupling, resonance peaks emerge. We map out the evolution of the resonance peaks from weak to strong coupling, which interpolate nicely between the two limits. There is a sudden qualitative change of behavior at intermediate coupling, indicating the possible existence of a local quantum phase transition. We also find that, even for a simple local phonon mode, the inherent coupling of spin and orbital degrees in topological insulators leads to the spin-polarized texture in inelastic Friedel oscillations induced by the local mode.

Based on a microscopic theoretical study, we show that novel superconductivity is induced by carrier doping in layered perovskite Ir oxides where a strong spin-orbit coupling causes an effective total angular momentum $J_{\mathrm{eff}}=1/2$ Mott insulator. Using a variational Monte Carlo method, we find an unconventional superconducting state in the ground state phase diagram of a $t_{2g}$ three-orbital Hubbard model on the square lattice. This superconducting state is characterized by a $d_{x^2\mathrm{\text{−}}{y}^2}$-wave “pseudospin singlet” formed by the $J_{\mathrm{eff}}=1/2$ Kramers doublet, which thus contains interorbital as well as both singlet and triplet components of $t_{2g}$ electrons. The superconducting state is found stable only by electron doping, but not by hole doping, for the case of carrier doped ${\mathrm{Sr}}_2{\mathrm{IrO}}_4$. We also study an effective single-orbital Hubbard model to discuss the similarities to high-$T_c$ cuprate superconductors and the multiorbital effects.

Spectral diffusion is the phenomenon of random jumps in the emission wavelength of narrow lines. This phenomenon is a major hurdle for applications of solid state quantum emitters like quantum dots, molecules, or diamond defect centers in an integrated quantum optical technology. Here, we provide further insight into the underlying processes of spectral diffusion of the zero-phonon line of single nitrogen vacancy centers in nano-size diamond by using a novel method based on photon correlation interferometry. The method works although the spectral diffusion rate is several orders of magnitude higher than the photon detection rate and thereby improves the time resolution of previous experiments with nano-size diamond by 6 orders of magnitude. We study the dependency of the spectral diffusion rate on the excitation power, temperature, and excitation wavelength under off-resonant excitation. Our results bring insight into the mechanism of spectral diffusion and suggest a strategy to increase the number of spectrally indistinguishable photons emitted by diamond nanocrystals.

Lipid membranes are commonly confined to adjacent subcellular structures or to artificial substrates and particles. We develop an experimental and theoretical framework to investigate the mechanics of confined membranes, including the influence of adhesion, strain, and osmotic pressure. We find that supported lipid bilayers respond to stress by nucleating and evolving spherical and tubular protrusions. In cells, such transformations are generally attributed to proteins. Our results offer insights into the mechanics of cell membranes and can further extend the applications of supported bilayers.

The limitation on obtaining precise outcomes of measurements performed on two noncommuting observables of a particle as set by the uncertainty principle in its entropic form can be reduced in the presence of quantum memory. We derive a new entropic uncertainty relation based on fine graining, which leads to an ultimate limit on the precision achievable in measurements performed on two incompatible observables in the presence of quantum memory. We show that our derived uncertainty relation tightens the lower bound set by entropic uncertainty for members of the class of two-qubit states with maximally mixed marginals, while accounting for the recent experimental results using maximally entangled pure states and mixed Bell-diagonal states. An implication of our uncertainty relation on the security of quantum key generation protocols is pointed out.

We determine the finite-temperature momentum distribution of a strongly interacting 1D Bose gas in the Tonks-Girardeau (impenetrable-boson) limit under harmonic confinement and explore its universal properties associated to the scale invariance of the model. We show that, at difference from the unitary Fermi gas in three dimensions, the weight of its large-momentum tails—given by Tan’s contact—increases with temperature and calculate the high-temperature universal second contact coefficient using a virial expansion.

We study time averages of single particle trajectories in scale-free anomalous diffusion processes, in which the measurement starts at some time $t_a>0$ after initiation of the process at $t=0$. Using aging renewal theory, we show that for such nonstationary processes a large class of observables are affected by a unique aging function, which is independent of boundary conditions or the external forces. Moreover, we discuss the implications of aging induced population splitting: with growing age $t_a$ of the process, an increasing fraction of particles remains motionless in a measurement of fixed duration. Consequences for single biomolecule tracking in live cells are discussed.

The ATLAS experiment has observed 1995 $Z$ boson candidates in data corresponding to $0.15{\mathrm{nb}}^{-1}$ of integrated luminosity obtained in the 2011 LHC $\mathrm{Pb}+\mathrm{Pb}$ run at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$. The $Z$ bosons are reconstructed via dielectron and dimuon decay channels, with a background contamination of less than 3%. Results from the two channels are consistent and are combined. Within the statistical and systematic uncertainties, the per-event $Z$ boson yield is proportional to the number of binary collisions estimated by the Glauber model. The elliptic anisotropy of the azimuthal distribution of the $Z$ boson with respect to the event plane is found to be consistent with zero.

The ${}^{63}\mathrm{Ni}(n,\gamma )$ cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from $kT=5–100\mathrm{keV}$ with uncertainties around 20%. Stellar model calculations for a $25M_{\odot }$ star show that the new data have a significant effect on the $s$-process production of ${}^{63}\mathrm{Cu}$, ${}^{64}\mathrm{Ni}$, and ${}^{64}\mathrm{Zn}$ in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

We present the first study of three-nucleon ($3N$) forces for proton-rich nuclei along the $N=8$ and $N=20$ isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all $N=8$ and $N=20$ isotones to the proton dripline, which agree well with experiment for ${}^{18}\mathrm{Ne}$, ${}^{19}\mathrm{Na}$, ${}^{20}\mathrm{Mg}$ and ${}^{42}\mathrm{Ti}$. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory.