The magneitc lines of force of a single flux quantum (fluxon) penetrating a superconducting film (Pb) were observed directly and individually by the electron holography technique using the Aharonov-Bohm effect. The phase contours of the electron wave not only confirm the quantized flux value h/2e but also reveal, by phase amplification, internal structure of a single fluxon. With the film thickness ≲0.5 μm, each fluxon, after penetrating the film, fans out or makes a ssU shape returning to another point on the film surface. With thicker films, fluxons form a bundle with a flux amounting to several times h/2e.

We have studied the electron transport in a one-dimensional electron interferometer. It consists of a disk-shaped two-dimensional electron gas, to which quantum point contacts are attached. Discrete zero-dimensional states are formed due to constructive interference of electron waves traveling along the circumference of the disk in one-dimensional magnetic edge channels. The conductance shows pronounced Aharonov-Bohm–type oscillations, with maxima occurring whenever the energy of a zero-dimensional state coincides with the Fermi energy. Good agreement with theory is found, taking energy averaging into account.

We rigorously treat the quantum mechanical propagation of a two-dimensional electron gas through multiterminal junctions. The elements $R_{\mathrm{mn}}$,kl of Büttiker’s global resistance tensor are calculated for ballistic motion. Our results confirm the occurrence of negative resistance observed in recent experiments and predict oscillations of the resistance as a function of ka, where k is the electron Fermi momentum and a is the geometrical dimension of the junction leads.

The precession of individual spins on partially oxidized Si(111) surfaces has been detected using a scanning tunneling microscope. The spin precession in a constant magnetic field induces a modulation in the tunneling current at the Larmor frequency. This radio-frequency signal is shown to be localized over distances less than 10 Å and follows the expected magnetic field dependence.

Coulomb blockade of single-electron tunneling and high sensitivity to an external electric field has been observed for 1D series arrays of ultra-small-area (<0.1×0.1 μ${\mathrm{m}}^2$) tunnel junctions, made of Al/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{O}}_{\mathrm{y}}$/Al, at helium temperatures. In particular, the dc voltage V across the array responds strongly to a voltage $U_g$ applied to a control electrode. For an array of thirteen junctions, the voltage gain $K_V$=‖δV/δ$U_g$‖ of the resulting sub-single-electron- transistors reached 0.2, while the charge sensitivity of the device was as high as 2×${10}^{\mathrm{-}4}$e/${\mathrm{Hz}}^{1/2}$ at a frequency f=10 Hz.

The time of Zener tunneling, ${\tau }_z$, is calculated for a general two-level quantum-mechanical system by two methods. In the first we determine the width of the transition profile in time. In the second we apply an oscillating perturbation and examine how the final transition probability depends upon the perturbation frequency and phase. Both methods show, given that the coupling energy between the diabatic levels is Δ and the time rate of change of the energy is α, that in the adiabatic limit ${\tau }_z$ scales as Δ/α and in the sudden limit ${\tau }_z$ scales as (ħ/α${)}^{1/2}$. We calculate the approximate transition probability at finite times for the two limits. The results can be applied to specific mesoscopic electronic systems.

The excitation of coherent transients in Mössbauer spectra has been previously limited by the high powers required to modulate the nuclear phases. Reported here is an orders-of-magnitude increase in the efficiency through which such phenomena can be produced. Magnetic modulation of the quantum phases of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ nuclei in paramagnetic media has been produced by spin waves of large amplitude transported from ferromagnetic sources.

The C 1s excitation spectrum of benzene chemisorbed on polycrystalline Cu and the C1s and N 1s spectra of pyridine adsorbed at submonolayer coverages on Cu and Ag(100) have been recorded by reflection inelastic electron scattering. The near-edge electron-energy-loss fine-structure spectra are found to be similar to the corresponding near-edge x-ray-absorption fine-structure spectra. The ability of reflection-electron-energy-loss spectroscopy to determine molecular orientation is demonstrated by the detection of different orientations of pyridine on the Cu and Ag(100) surfaces.

The pressure derivatives of the spin-split ${\mathrm{\Gamma }}_{30}$ Fermi-surface cross-sectional areas in ferromagnet ${\mathrm{ZrZn}}_2$ have been determined from a phase-shift analysis of the de Haas–van Alphan oscillations. The difference between these derivatives is inconsistent with a Stoner-Wohlfarth interpretation of both the pressure-dependent beat frequency between the two oscillations and the pressure-dependent magnetization.

Giant Shubnikov–de Haas oscillations have been observed in the high-$T_c$ phase (${\beta }_H$) of an organic conductor β-(BEDT-TTF${)}_2$${\mathrm{I}}_3$. The frequency of the oscillations ($H_0$=3730T) Corresponds to about one carrier per unit cell. The extraordinary large amplitude of the magnetoresistance oscillations has been attributed to the two-dimensional nature of the cylindrical Fermi surface exhibiting only a small warping along the direction of lowest conductivity.

We solve the diffusion-limited single-species coagulation process (A+A→A) with random particle input in one spatial dimension. We derive the exact time-dependent concentration, the spectrum of relaxation rates, and the distribution of interparticle distances in the nonequilibrium steady state. These results imply an interesting microscopic spatial structure induced by the nonequilibrium constraints. The validity of rate-equation descriptions of the macroscopic statics and kinetics is investigated, and we compare our results to the closely related single-species annihilation process (A+A→inert) in the presence of input.

We describe the statistical mechanics of a D-dimensional Gaussian crumpled manifold embedded in d-dimensional space, and interacting by excluded volume with an Euclidean D’-dimensional subspace of ${\mathrm{R}}^d$. The effective theory describes a self-interacting manifold. An ε expansion [ε=D-(2-D)(d-D’)/2] is devised. Its one-loop renormalizability is proven to all orders, giving the first step towards that of self-avoiding manifolds.

We consider the relativistic interaction of a charged particle with obliquely propagating waves of arbitrary polarization. We show that an arbitrarily small wave packet with parallel phase velocity comparable to the speed of light can, under certain conditions, accelerate particles to unlimited energy through a process of Arnol’d diffusion in two-dimensions.

We give a new definition of a quasilocal mass function in general relativity which is uniquely defined, manifestly non-negative, and increases with increasing domains. This mass function agrees with the Schwarzschild mass for spherically symmetric spacetimes.

We prove that in the scale-invariant limit of walking technicolor the fermion dynamical mass function falls off exactly as 1/p when the gauge coupling α just reaches the critical value required to trigger spontaneous chiral-symmetry breaking. The proof is given to all orders in α.

We find that narrow lines at 1043 and 1062 keV in the summed-energy, 180°-correlated two-photon spectrum from ≊6-MeV/nucleon U+Th collisions can be produced by cascades from high-spin states (${32}^{+}$) in ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. We see no evidence for narrow two-photon lines in U+Th, Th+Th, and U+U collisions corresponding to the electron-positron lines seen by others: In the summed-energy region between 1.2 and 2.0 MeV, we set an upper limit for the cross section of 6×${10}^{\mathrm{-}31}$ ${\mathrm{cm}}^2$ averaged over a target thickness of 1 mg/${\mathrm{cm}}^2$.

The binding energy, density, and incompressibility (saturation properties) of normal nuclear matter are reproduced using a Lagrangian with approximate chiral symmetry. The pion-ring series including nucleons and Δ’s provides the necessary attraction and its density dependence, while the effects of the scalar field are not significant, and vacuum-polarization effects are expected to be small.

We duscuss a resonant microwave trap for neutral atoms. Because of the long spontaneous radiation time this trap is remarkably different from the optical trap. It also has advantages over static magnetic traps that trap the excited spin state of the lowest electronic level, in that atoms predominantly in the spin ground state can be trapped. We analyze the relaxation-ejection lifetime of atoms in such a trap using the formalism of dressed atomic states. Results are appliedi to atomic hydrogen and the possibility of Bose-Einstein condensation is considered.

Highly excited double-Rydberg states Nln’l’ of barium have been observed for N=22 to 34 and n’=39 to 60. The experimental data trace the evolution from states in which the electrons are uncorrelated (N≪n’) to those (N∼0.6n’) in which they are. These features can be interpreted as resulting from the polarization of the excited ${\mathrm{Ba}}^{+}$ (Nl) core by the outer (n’l’) electron. A generalization of the isolated core excitation formalism taking into account dipole and quadrupole terms leads us to a quantitative understanding of the long-range electronic correlation observed.