Magnetic resonance measurements of migration and irreversible dynamics in the capillary shear flow of a Brownian suspension are presented. The results demonstrate the presence of phenomena typically associated with concentrated noncolloidal systems and indicate the role of many body hydrodynamics in dilute Brownian suspension transport. The application of concepts from chaos theory and nonequilibrium statistical mechanics is demonstrated.

Foams with 55% and 76% open porosity were produced from a Ni-Mn-Ga magnetic shape-memory alloy by replication casting. These polycrystalline martensitic foams display a fully reversible magnetic-field-induced strain of up to 0.115% without bias stress, which is about 50 times larger than nonporous, fine-grained Ni-Mn-Ga. This very large improvement is attributed to the bamboolike structure of grains in the foam struts which, due to reduced internal constraints, deform by magnetic-field-induced twinning more easily than equiaxed grains in nonporous Ni-Mn-Ga.

We investigate physical properties that can be used to distinguish the valley degree of freedom in systems where inversion symmetry is broken, using graphene systems as examples. We show that the pseudospin associated with the valley index of carriers has an intrinsic magnetic moment, in close analogy with the Bohr magneton for the electron spin. There is also a valley dependent Berry phase effect that can result in a valley contrasting Hall transport, with carriers in different valleys turning into opposite directions transverse to an in-plane electric field. These effects can be used to generate and detect valley polarization by magnetic and electric means, forming the basis for the valley-based electronics applications.

A Brownian particle moving in the vicinity of a generic potential minimum under the influence of dissipation and thermal noise from two different heat baths is shown to act as a minimal heat engine, generating a systematic torque onto the physical object at the origin of the potential and an opposite torque onto the medium generating the dissipation.

Using time-dependent density-functional theory we calculate from first principles the rate of energy transfer from a moving proton or antiproton to the electrons of an insulating material, LiF. The behavior of the electronic stopping power versus projectile velocity displays an effective threshold velocity of $\sim 0.2\mathrm{a}.\mathrm{u}.$ for the proton, consistent with recent experimental observations, and also for the antiproton. The calculated proton/antiproton stopping-power ratio is $\sim 2.4$ at velocities slightly above the threshold ($v\sim 0.4\mathrm{a}.\mathrm{u}.$), as compared to the experimental value of 2.1. The projectile energy loss mechanism is observed to be extremely local.

We show that an extremal Kerr black hole, appropriately lifted to M theory, can be transformed to a Kaluza-Klein black hole in M theory, or a D0–D6 charged black hole in string theory. Since all the microstates of the latter have recently been identified, one can exactly reproduce the entropy of an extremal Kerr black hole. We also show that the topology of the event horizon is not well defined in M theory.

We propose a real-space renormalization group (RG) transformation for quantum systems on a $D$-dimensional lattice. The transformation partially disentangles a block of sites before coarse-graining it into an effective site. Numerical simulations with the ground state of a 1D lattice at criticality show that the resulting coarse-grained sites require a Hilbert space dimension that does not grow with successive RG transformations. As a result we can address, in a quasi-exact way, tens of thousands of quantum spins with a computational effort that scales logarithmically in the system’s size. The calculations unveil that ground state entanglement in extended quantum systems is organized in layers corresponding to different length scales. At a quantum critical point, each relevant length scale makes an equivalent contribution to the entanglement of a block.

Excitons are generally believed not to exist in metals because of strong screening by free carriers. Here we demonstrate that excitonic states can in fact be produced in metallic systems of a one-dimensional character. Using metallic single-walled carbon nanotubes as a model system, we show both experimentally and theoretically that electron-hole pairs form tightly bound excitons. The exciton binding energy of 50 meV, deduced from optical absorption spectra of individual metallic nanotubes, significantly exceeds that of excitons in most bulk semiconductors and agrees well with ab initio theoretical predictions.

We demonstrate that a microwave signal carried by a packet of dipolar spin waves propagating in a tangentially magnetized magnetic film can be stored in the form of standing dipole-exchange spin-wave modes of the film and can be recovered by means of a double-frequency parametric pumping mechanism. This mechanism is based on the parametric amplification of the standing (thickness) modes of the film by external pumping. The time of recovery, duration, and power of the recovered pulse signal are controlled by the power of the pumping signal.

Bell’s theorem guarantees that no model based on local variables can reproduce quantum correlations. Also, some models based on nonlocal variables, if subject to apparently “reasonable” constraints, may fail to reproduce quantum physics. In this Letter, we introduce a family of inequalities, which use a finite number of measurement settings, and which therefore allow testing Leggett’s nonlocal model versus quantum physics. Our experimental data falsify Leggett’s model and are in agreement with quantum predictions.

We report the first observation of Airy optical beams. This intriguing class of wave packets, initially predicted by Berry and Balazs in 1979, has been realized in both one- and two-dimensional configurations. As demonstrated in our experiments, these Airy beams can exhibit unusual features such as the ability to remain diffraction-free over long distances while they tend to freely accelerate during propagation.

The Aharonov-Bohm (AB) effect is a purely quantum mechanical effect. The original (classified as type-I) AB-phase shift exists in experimental conditions where the electromagnetic fields and forces are zero. It is the absence of forces that makes the AB effect entirely quantum mechanical. Although the AB-phase shift has been demonstrated unambiguously, the absence of forces in type-I AB effects has never been shown. Here, we report the observation of the absence of time delays associated with forces of the magnitude needed to explain the AB-phase shift for a macroscopic system.

We present a precise theoretical prediction for the decay width of the bound state of two electrons and a positron (a negative positronium ion), $\Gamma ({\mathrm{Ps}}^{-})=2.087963(12)/\mathrm{ns}$. We include $O({\alpha }^2)$ effects of hard virtual photons as well as soft corrections to the wave function and the decay amplitude. An outcome of a large-scale variational calculation, this is the first result for second-order corrections to a decay of a three-particle bound state. It will be tested experimentally in the new positronium-ion facility in Garching in Germany.

An extension of the Drude model is proposed that accounts for the spin and spin-orbit interaction of charge carriers. Spin currents appear due to the combined action of the external electric field, crystal field, and scattering of charge carriers. The expression for the spin Hall conductivity is derived for metals and semiconductors that is independent of the scattering mechanism. In cubic metals, the spin Hall conductivity ${\sigma }_s$ and charge conductivity ${\sigma }_c$ are related through ${\sigma }_s=[2\pi \hslash /(3m{c}^2)]{\sigma }_c^2$ with $m$ being the bare electron mass. The theoretically computed value is in agreement with experiment.

We study phonons in a dynamical chain of ions confined by a trap with a time-dependent (axial) potential strength and demonstrate that they behave in the same way as quantum fields in an expanding or contracting Universe. Based on this analogy, we present a scheme for the detection of the analogue of cosmological particle creation which should be feasible with present day technology. In order to test the quantum nature of the particle creation mechanism and to distinguish it from classical effects such as heating, we propose to measure the two-phonon amplitude via the 2nd red sideband transition and to compare it with the one-phonon amplitude (1st red sideband).

We study phase separation in a deeply quenched colloid-polymer mixture in microgravity on the International Space Station using small-angle light scattering and direct imaging. We observe a clear crossover from early-stage spinodal decomposition to late-stage, interfacial-tension-driven coarsening. Data acquired over 5 orders of magnitude in time show more than 3 orders of magnitude increase in domain size, following nearly the same evolution as that in binary liquid mixtures. The late-stage growth approaches the expected linear growth rate quite slowly.

Small-angle neutron scattering experiments and molecular dynamics simulations combined with an application of concepts from soft matter physics to complex protein mixtures provide new insight into the stability of eye lens protein mixtures. Exploring this colloid-protein analogy we demonstrate that weak attractions between unlike proteins help to maintain lens transparency in an extremely sensitive and nonmonotonic manner. These results not only represent an important step towards a better understanding of protein condensation diseases such as cataract formation, but provide general guidelines for tuning the stability of colloid mixtures, a topic relevant for soft matter physics and industrial applications.

Spontaneous emission rate enhancements from a single quantum dot embedded in a finite-size, planar photonic-crystal waveguide are investigated. Short waveguide lengths of only 10 to 20 unit cells are found to produce very large Purcell factors associated with a waveguidelike sharp resonance feature in the local density of photon states. Aided by theoretical insight and rigorous computational calculations, we explain the physics behind these remarkable emission enhancements and subsequently propose a “single-photon gun” with on-chip unidirectional collection efficiencies greater than 60% into an output wire waveguide. The advantages over recent proposals for infinitely long photonic-crystal waveguides are highlighted.

New measurements of fusion cross sections at deep sub-barrier energies for the reactions ${}^{16}\mathrm{O}+{}^{204,208}\mathrm{Pb}$ show a steep but almost saturated logarithmic slope, unlike ${}^{64}\mathrm{Ni}$-induced reactions. Coupled channels calculations cannot simultaneously reproduce these new data and above-barrier cross-sections with the same Woods-Saxon nuclear potential. It is argued that this highlights an inadequacy of the coherent coupled channels approach. It is proposed that a new approach explicitly including gradual decoherence is needed to allow a consistent description of nuclear fusion.

The decay of extremely neutron-deficient ${}^{45}\mathrm{Fe}$ has been studied in detail by means of a novel type of a gaseous detector employing digital imaging to record tracks of charged particles. The two-proton radioactivity channel was clearly identified. For the first time, the angular and energy correlations between two protons emitted from the nuclear ground state were determined, indicating the genuine three-body character of this decay. The half-life of ${}^{45}\mathrm{Fe}$ was found to be $2.6\pm 0.2\mathrm{ms}$ and the observed $2p$ decay branching ratio is $70\pm 4\%$.