Physical Review Letters

Gustafson, J; Mikkelsen, A; Borg, M; Lundgren, E; Köhler, L; Kresse, G; Schmid, M; Varga, P; Yuhara, J; Torrelles, X; Quirós, C; Andersen, J. N

doi: 10.1103/PhysRevLett.92.126102pmid: 15089690

The oxidation of the Rh(111) surface at oxygen pressures from 10 - 10 mbar to 0.5 bar and temperatures between 300 and 900 K has been studied on the atomic scale using a multimethod approach of experimental and theoretical techniques. Oxidation starts at the steps, resulting in a trilayer O-Rh-O surface oxide which, although not thermodynamically stable, prevents further oxidation at intermediate pressures. A thick corundum like Rh 2 O 3 bulk oxide is formed only at significantly higher pressures and temperatures.

Randrup, Jørgen

doi: 10.1103/PhysRevLett.92.122301pmid: 15089667

The expansion of strongly interacting matter formed in high-energy nuclear collisions drives the system through the region of phase coexistence. The present study examines the associated spinodal instability and finds that the degree of amplification may be sufficient for the emergence of spinodal patterns that may be utilized as a diagnostic of the hadronization phase transition.

Kumar, Sanjeev ; Majumdar, Pinaki

doi: 10.1103/PhysRevLett.92.126602pmid: 15089694

We study the nanoscale phase coexistence of ferromagnetic metallic and antiferromagnetic insulating (AFI) regions by including the effect of AF superexchange and weak disorder in the double exchange model. We use a new Monte Carlo technique, mapping on the disordered spin-fermion problem to an ef<?format ?>fective short range spin model, with self-consistently computed exchange constants. We recover “clus<?format ?>ter coexistence” as seen earlier in exact simulation of small systems. The much larger sizes, ∼ 32 × 32 , accessible with our technique, allow us to study the cluster pattern for varying electron density, disorder, and temperature. We track the magnetic structure, obtain the density of states, with its “pseudogap” features, and, for the first time, provide a fully microscopic estimate of the resistivity in a phase coexistence regime, comparing it with the “percolation” scenario.

Tanaka, S; Egelhaaf, S. U; Poon, W. C

doi: 10.1103/PhysRevLett.92.128102pmid: 15089713

We studied the crystallization of a globular protein, lysozyme, in the cubic phase of the lipid mono-olein. The solubility of lysozyme in salt solution decreased by a factor of ∼ 4 when confined in cubic phase. Monte Carlo simulations and calculations show that this can be explained by the confinement of lysozyme molecules to the narrow water cells in the cubic phase.

Shapiro, S. S; Davis, J. L; Lebach, D. E; Gregory, J. S

doi: 10.1103/PhysRevLett.92.121101pmid: 15089661

We used very-long-baseline interferometry (VLBI) to measure the deflection by the Sun of radio waves emanating from distant compact radio sources. This bending is characterized in the parametrized post-Newtonian formalism by γ , which is unity in general relativity. Using a large geodetic VLBI data set, we obtained γ = 0.9998 3 ± 0.0004 5 (estimated standard error). We found no systematic biases from our analysis of subgroups of data.

Law, C. K; Eberly, J. H

doi: 10.1103/PhysRevLett.92.127903pmid: 15089711

Quantum entanglement associated with transverse wave vectors of down conversion photons is investigated based on the Schmidt decomposition method. We show that transverse entanglement involves two variables: orbital angular momentum and transverse frequency. We show that in the monochromatic limit high values of entanglement are closely controlled by a single parameter resulting from the competition between (transverse) momentum conservation and longitudinal phase matching. We examine the features of the Schmidt eigenmodes, and indicate how entanglement can be enhanced by suitable mode selection methods.

Bartenstein, M; Altmeyer, A; Riedl, S; Jochim, S; Chin, C; Denschlag, J. Hecker; Grimm, R. Hecker

doi: 10.1103/PhysRevLett.92.120401pmid: 15089653

We demonstrate a reversible conversion of a Li 2 6 molecular Bose-Einstein condensate to a degenerate Fermi gas of atoms by adiabatically crossing a Feshbach resonance. By optical in situ imaging, we observe a smooth change of the cloud size in the crossover regime. On the Feshbach resonance, the ensemble is strongly interacting and the measured cloud size is 75 ( 7 ) % of the one of a noninteracting zero-temperature Fermi gas. The high condensate fraction of more than 90 % and the adiabatic crossover suggest our Fermi gas to be cold enough to form a superfluid.

Batista, Adriano A; Citrin, D. S

doi: 10.1103/PhysRevLett.92.127404pmid: 15089706

We obtain pulse-driven Rabi oscillations guided by a generalization of the rotating-wave approximation to include, in the optical-Bloch equations, two-level systems with a time-varying transition energy. We achieve this by using chirped pulses with the central frequency given by the time-varying transition energy. Using this approach, we predict Rabi oscillations in intersubband transitions in a two-subband n -type modulation-doped quantum well by taking into account the time-dependent intersubband energy-gap renormalization due to depolarization-shift effects. We obtain Rabi oscillations for j π ( j = 0 , 1 , 2 , … ) pulses in the presence of dephasing.

Widmann, K; Ao, T; Foord, M. E; Price, D. F; Ellis, A. D; Springer, P. T; Ng, A. T

doi: 10.1103/PhysRevLett.92.125002pmid: 15089680

We report on a single-state measurement of electrical conductivity of warm dense gold in the solid to plasma transition regime. This is achieved using the idealized slab plasma approach of isochoric heating of ultrathin samples by a femtosecond laser, coupled with femtosecond probe measurements of reflectivity and transmission. The experiment also reveals the time scale associated with the disassembly of laser heated solid.

Rijs, Anouk M; Janssen, Maurice H

doi: 10.1103/PhysRevLett.92.123002pmid: 15089669

The novel technique of femtosecond time-resolved photoelectron-photoion coincidence imaging is applied to unravel dissociative ionization processes in a polyatomic molecule. Femtosecond coincidence imaging of CF 3 I photodynamics illustrates how competing multiphoton dissociation pathways can be distinguished, which would be impossible using photoelectron or ion imaging alone. Ion-electron energy correlations and photoelectron angular distributions reveal competing processes for the channel producing ( e - + CF 3 + + I ). The molecular-frame photoelectron angular distributions of the two major pathways are strikingly different.