Physical Review Letters

Romano, Alfonso; Gentile, Paola; Noce, Canio; Vekhter, Ilya; Cuoco, Mario

doi: 10.1103/PhysRevLett.110.267002pmid: 23848911

We show that a spontaneous magnetic moment may appear at the edge of a spin-triplet superconductor if the system allows for pairing in a subdominant channel. To unveil the microscopic mechanism behind such an effect, we combine numerical solution of the Bogoliubov–de Gennes equations for a tight-binding model with nearest-neighbor attraction, and the symmetry based Ginzburg-Landau approach. We find that a potential barrier modulating the electronic density near the edge of the system leads to a nonunitary superconducting state close to the boundary where spin-singlet pairing coexists with the dominant triplet superconducting order. We demonstrate that the spin polarization at the edge appears due to the inhomo<?format ?>geneity of the nonunitary state and originates in the lifting of the spin degeneracy of the Andreev <?format ?>bound states.

Sanloup, Chrystèle

doi: 10.1103/PhysRevLett.110.265501pmid: 23848893

We report results from high pressure and temperature experiments that provide evidence for the reactivity of xenon with water ice at pressures above 50 GPa and a temperature of 1500 K—conditions that are found in the interiors of Uranus and Neptune. The x-ray data are sufficient to determine a hexagonal lattice with four Xe atoms per unit cell and several possible distributions of O atoms. The <?format ?>measurements are supplemented with ab initio calculations, on the basis of which a crystallographic structure with a Xe 4 O 12 H 12 primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and η - O 2 , and has the same oxygen subnetwork as the latter. Furthermore, it has a weakly metallic character and likely undergoes sublattice melting of the H subsystem. Our findings indicate that Xe is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth.

Achilleos, V; Frantzeskakis, D. J; Kevrekidis, P. G; Pelinovsky, D. E

doi: 10.1103/PhysRevLett.110.264101pmid: 23848877

We study matter-wave bright solitons in spin-orbit coupled Bose-Einstein condensates with attractive interactions. We use a multiscale expansion method to identify solution families for chemical potentials in the semi-infinite gap of the linear energy spectrum. Depending on the linear and spin-orbit coupling strengths, the solitons may present either a sech 2 -shaped or a modulated density profile reminiscent of the stripe phase of spin-orbit coupled repulsive Bose-Einstein condensates. Our numerical results are in excellent agreement with our analytical findings and demonstrate the potential robustness of solitons for experimentally relevant conditions.

Li, H.; Liao, H.; Lin, S.; Liu, S.; Singh, L.; Singh, M.; Soma, A.; Wong, H.; Wu, Y.; Zhao, W.; Asryan, G.; Chuang, Y.; Deniz, M.; Fang, J.; Hsu, C.; Huang, T.; Kiran Kumar, G.; Lee, S.; Li, J.; Li, J.; Li, Y.; Li, Y.; Lin, C.; Lin, F.;

Müller, Tim-Oliver

doi: 10.1103/PhysRevLett.110.260401pmid: 23848847

For scattering by potentials with attractive inverse-cube ( <?format ?>- C 3 / r 3 ) tails, the threshold law for elastic collisions is presented. The expansion of the scattering phase shift contains all terms up to and including O ( k 2 ) and only relies on the value of the threshold quantum number’s remainder Δ ∈ ( 0 , 1 ) , which accounts for short-range deviations of the full potential from the pure - C 3 / r 3 form. In contrast to previous approaches, the threshold law presented provides a connection to the regular solution at zero energy as well as to the position of a weakly bound s -wave state.

de Sousa, Rogério; Allen, Marc

doi: 10.1103/PhysRevLett.110.267202pmid: 23848915

We present a microscopic theory that shows the importance of spin-orbit coupling in perovskite compounds with heavy ions. In BiFeO 3 (BFO) the spin-orbit coupling at the bismuth ion sites results in <?format ?>a special kind of magnetic anisotropy that is linear in the applied E field. This interaction can convert <?format ?>the cycloid ground state into a homogeneous antiferromagnet, with a weak ferromagnetic moment whose orientation can be controlled by the E -field direction. Remarkably, the E -field control of magnetism occurs without poling the ferroelectric moment, providing a pathway for reduced energy dissipation in spin-based devices made of insulators.

Zaidi, Hussain; van Loock, Peter

doi: 10.1103/PhysRevLett.110.260501pmid: 23848856

We show that optically encoded two-qubit Bell states can be unambiguously discriminated with a success probability of more than 50% in both single-rail and dual-rail encodings by using active linear-optical resources that include Gaussian squeezing operations. These results are in contrast to the well-known upper bound of 50% for unambiguous discrimination of dual-rail Bell states using passive, static linear optics and arbitrarily many vacuum modes. We present experimentally feasible schemes that improve the success probability to 64.3% in dual-rail and to 62.5% in single-rail for a uniform random distribution of Bell states. Conceptually, this demonstrates that neither interactions that induce nonlinear mode transformations (such as Kerr interactions) nor auxiliary entangled photons are required to go beyond the one-half limit. We discuss the optimality of our single-rail scheme and talk about an application of our dual-rail scheme in quantum communication.

Akers, C; Laird, A. M; Fulton, B. R; Ruiz, C. R; Bardayan, D. W; Buchmann, L. W; Christian, G. W; Davids, B. W; Erikson, L. W; Fallis, J. W; Hager, U. W; Hutcheon, D. W; Martin, L. W; Murphy, A. St; Nelson, K. St; Spyrou, A. St;

Chaput, Laurent

doi: 10.1103/PhysRevLett.110.265506pmid: 23848898

The frequency dependent phonon Boltzmann equation is transformed to an integral equation over the irreducible part of the Brillouin zone. Simultaneous diagonalization of the collision kernel of that equation and a symmetry crystal class operator allow us to obtain a spectral representation of the lattice thermal conductivity valid at finite frequency. Combining this approach with density functional calculations, an ab initio dynamical thermal conductivity is obtained for the first time. The static thermal conductivity is also obtained as a particular case. The method is applied to C, Si, and Mg 2 Si and excellent agreement is obtained with the available static thermal conductivity measurements.

Chen, Jiunn-Wei ; Pu, Shi ; Wang, Qun ; Wang, Xin-Nian

doi: 10.1103/PhysRevLett.110.262301pmid: 23848865

We derive a relativistic chiral kinetic equation with manifest Lorentz covariance from Wigner functions of spin- 1 / 2 massless fermions in a constant background electromagnetic field. It contains vorticity <?format ?>terms and a four-dimensional Euclidean Berry monopole which gives an axial anomaly. By integrating <?format ?>out the zeroth component of the 4-momentum p , we reproduce the previous three-dimensional results derived from the Hamiltonian approach, together with the newly derived vorticity terms. The phase <?format ?>space continuity equation has an anomalous source term proportional to the product of electric and magnetic fields ( F σ ρ F ˜ σ ρ ∼ E σ B σ ). This provides a unified interpretation of the chiral magnetic and vortical effects, chiral anomaly, Berry curvature, and the Berry monopole in the framework of Wigner functions.