We show that gravitational radiation drives an instability in hot young rapidly rotating neutron stars. This instability occurs primarily in the $l=2\mathrm{}$ $r$-mode and will carry away most of the angular momentum of a rapidly rotating star by gravitational radiation. On the time scale needed to cool a young neutron star to about ${T=10\mathrm{}}^9\mathrm{K}$ (about one year) this instability can reduce the rotation rate of a rapidly rotating star to about $0.076{\Omega }_K$, where ${\Omega }_K$ is the Keplerian angular velocity where mass shedding occurs. In older colder neutron stars this instability is suppressed by viscous effects, allowing older stars to be spun up by accretion to larger angular velocities.

We demonstrate that the well-known $\mathrm{Si}\left(111\right)-(7\times 7)$ superlattice buried under as much as 100 Å of crystalline Pb can be directly imaged with a scanning tunneling microscope at 77 K. The unexpected transparency of the metal and the high lateral resolution are the result of a nondiffractive scattering of the electrons at the interface. We attribute this phenomenon to a large anisotropy of the effective masses associated with the free in-plane and the quantized transverse motion of the electrons.

It is experimentally demonstrated that a transition from a synclinic to an anticlinic liquid crystal phase occurs via stable domain wall propagation after quenching in a uniform temperature field. Such a one-dimensional growth may be explained in terms of a nonlinear diffusion equation. The experiment provides the first example of free, one-dimensional growth in a system subjected to a pure and uniform temperature field.

We report the first real time imaging of single fluorophores attached to protein molecules on metal surfaces in aqueous solution using surface plasmon resonance fluorescence microscopy. The fluorescence was enhanced by the surface plasmons as theoretically predicted for gold and silver. Active movement of single molecules of the fluorescently labeled motor protein, coupled to the ATPase reaction, was observed on the surfaces of gold and aluminum. This microscopy should prove a powerful tool to directly detect single molecule processes in biomolecule systems organized on a metal surface.

We report on the experimental observation of environment induced decoherence in the quantum delta-kicked rotor. Ultracold cesium atoms are subjected to a pulsed standing wave of near resonant light. Spontaneous scattering of photons destroys dynamical localization thereby giving rise to a quantum diffusion, which approaches the classical diffusion with an increasing degree of decoherence. This tendency is enhanced by a stronger stochasticity in the underlying classical system. A comparison with theoretical predictions is presented.

The combination of cold atoms and large coherent coupling enables investigations in a new regime in cavity QED with single-atom trajectories monitored in real time with high signal-to-noise ratio. The underlying “vacuum-Rabi” splitting is clearly reflected in the frequency dependence of atomic transit signals recorded atom by atom, with evidence for mechanical light forces for intracavity photon number $<1\mathrm{}$. The nonlinear optical response of one atom in a cavity is observed to be in accord with the one-atom quantum theory but at variance with semiclassical predictions.

We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and subject one photon from each pair to a Bell-state measurement. This results in projecting the other two outgoing photons into an entangled state.

Breakup temperatures in central collisions of ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ at bombarding energies $E/A=50\mathrm{}$ to 200 MeV were determined with two methods. Isotope temperatures, deduced from double ratios of hydrogen, helium, and lithium isotopic yields, increase monotonically with bombarding energy from 5 to 12 MeV, in qualitative agreement with a scenario of chemical freeze-out after adiabatic expansion. Excited-state temperatures, derived from yield ratios of states in ${}^4\mathrm{He}$, ${}^{5,6}\mathrm{Li}$, and ${}^8\mathrm{Be}$, are about 5 MeV, independent of the projectile energy, and seem to reflect the internal temperature of fragments at their final separation from the system.

We report a principle that allows one to write visible light emitting silicon patterns of arbitrary shape down to the submicrometer scale. We demonstrate that porous Si growth can electrochemically be initiated preferentially at surface defects created in an $n$-type Si substrate by ${\mathrm{Si}}^{++}$ focused ion beam bombardment. For $n$-type material in the dark, the electrochemical pore formation potential (Schottky barrier breakdown voltage) is significantly lower at the implanted locations than for an unimplanted surface. This difference in the threshold voltages is exploited to achieve the selectivity of the pore formation process.

We study the equilibrium phase diagram of binary mixtures of hard spheres as well as of parallel hard cubes. A superior cluster algorithm allows us to establish and to access the demixed phase for both systems and to investigate the subtle interplay between short-range depletion and long-range demixing.

Based on first-principles calculations, an Sb film on GaAs(110) is found to be nonmetallic at 1 and 3 monolayer (ML) coverages, and metallic at 2, 4, and higher ML coverages. These unusual oscillatory nonmetal-metal transitions are explained in terms of a generalized Wilson rule, constrained by the relative magnitudes of the separation and width of the subbands derived from the quantum-well states. The present study also establishes the existence of magic stability of the film at the odd numbers of monolayers, and strong interlayer spacing oscillations.

From considering the effect of $\gamma$- $\gamma$ interactions on recently observed TeV gamma-ray spectra, improved limits are set to the density of extragalactic infrared photons which are robust and essentially model independent. The resulting limits are more than an order of magnitude more restrictive than direct observations in the 0.025–0.3 eV regime. These limits are used to improve constraints on radiative neutrino decay in the mass range above 0.05 eV and to rule out very massive objects as providing the dark matter needed to explain galaxy rotation curves. Lower bounds on the maximum distance which TeV gamma rays may probe are also derived.

We point out that the matrix description of $M$ theory compactified on Calabi-Yau threefolds is in many respects simpler than the matrix description of a $T^6$ compactification. This is largely because of the differences between D6-branes wrapped on Calabi-Yau threefolds and D6-branes wrapped on six-tori. In particular, if we define the matrix theory following the prescription on Sen and Seiberg, we find that the remaining degrees of freedom are decoupled from gravity.

Atomic scale modification of surfaces may trigger off dynamical processes. This is shown here by using the tip of a scanning tunneling microscope to extract an individual atom in a controlled manner from a predefined site of the reconstructed Ge(111)- $c$(2 $\times$8) surface. By thermally activated hopping of neighboring adatoms to the vacant site, the produced single-atom vacancy diffuses on the surface. From statistical analysis of the adatom configurations observed around the vacancy, we determine tiny ( $<$0.15 eV) differences in free energy between the configurations. A linear increase of the configuration free energy with the number of adatoms located at metastable $T_4$ sites is reported.

We present a measurement of the top quark mass using a sample of $t\overline{t}$ decays into an electron or a muon, a neutrino, and four jets. The data were collected in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{TeV}$ with the Collider Detector at Fermilab and correspond to an integrated luminosity of $109{\mathrm{pb}}^{-1\mathrm{}}$. We measure the top quark mass to be $175.9\pm 4.8\left(\mathrm{stat}\right)\pm 4.9\left(\mathrm{syst}\right)\mathrm{GeV}{/c}^2$.

We present an analysis of dilepton events originating from $t\overline{t}$ production in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{TeV}$ at the Fermilab Tevatron Collider. The sample corresponds to an integrated luminosity of $109\pm 7{\mathrm{pb}}^{-1\mathrm{}}$. We observe nine candidate events, with an estimated background of $2.4\pm 0.5$ events. We determine the mass of the top quark to be $M_{\mathrm{top}}=161\mathrm{}\pm 17\left(\mathrm{stat}\right)\pm 10\left(\mathrm{syst}\right)\mathrm{GeV}{/c}^2$. In addition, we measure a $t\overline{t}$ production cross section of ${8.2}_{-3.4\mathrm{}}^{+4.4\mathrm{}}\mathrm{pb}$ (where $M_{\mathrm{top}}=175\mathrm{GeV}{/c}^2$ has been assumed for the acceptance estimate).

We introduce a new type of metallo-dielectric photonic band gap structure (PBG), intentionally incorporating very strong capacitive interactions between the periodic metallic islands. The band gaps become huge, with the lower band edge frequency being pushed down by the capacitive interaction between metallic islands, while the upper band edge frequency continues to depend primarily on the lattice constant, as in normal PBG's. With this new type of photonic crystal, the spatial periodicity can be much smaller than the corresponding electromagnetic wavelength, allowing PBG structures to play a role at radio frequencies.

We present the first measurements of radiation temperatures and stimulated scattering losses in laser-driven, gas-filled hohlraums. They show efficient coupling when applying laser beam smoothing techniques. Scattering losses are reduced to the 3% level while the radiation temperatures increased by $\sim 15$ eV for smoothed laser beams. We observe peak radiation temperatures in excess of 230 eV in gas-filled hohlraums consistent with detailed hydrodynamic LASNEX modeling.

Binary black-hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from the Binary Black Hole Grand Challenge Alliance three-dimensional Cauchy evolution module. These constitute essential steps towards modeling such interactions and predicting gravitational radiation waveforms. We report on single black-hole evolutions and the first successful demonstration of a black hole moving freely through a three-dimensional computational grid via a Cauchy evolution: a hole moving near $6M$ at $0.1c$ during a total evolution of duration near $60M$.

We report on a measurement of the ${}^{44}\mathrm{Ti}$ half-life aimed at lowering existing systematic uncertainties in this value, which is important to astrophysics. The half-life was measured by following the decay of ${}^{44}\mathrm{Ti}$ relative to ${}^{60}\mathrm{Co}$ for about 5 yr and the measurements were performed independently in three laboratories—Argonne, Jerusalem, and Torino. We suggest to combine our result, $59.0\pm 0.6$ yr, with the one from the accompanying Letter by Görres et al., $60.3\pm 1.3$ yr, to obtain a current “best value” for the half-life of ${}^{44}\mathrm{Ti}$ of $59.2\pm 0.6$ yr ( $1\sigma$ error).