Propagation of a Dark Soliton in a Disordered Bose-Einstein Condensate

We consider the propagation of a dark soliton in a quasi 1D Bose-Einstein condensate in presence of a random potential. This configuration involves nonlinear effects and disorder, and we argue that, contrarily to the study of stationary transmission coefficients through a nonlinear disordered slab, it is a well defined problem. It is found that a dark soliton decays algebraically, over a characteristic length which is independent of its initial velocity, and much larger than both the healing length and the 1D scattering length of the system. We also determine the characteristic decay time.Comment: 4 pages, 2 figure

Microcircuit testing and fabrication, using scanning electron microscopes

Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances

Three-core weakly-guiding mode-selective fibre couplers

The coupling behaviour of two-core mode-selective couplers (MSC) depends on the spatial-orientation of the asymmetric higher-order modes. This restricts their use for mode de-multiplexing in few-mode fibre networks. The use of three-core MSC's is presented as a solution

Gamow-Teller properties of the double beta-decay partners 116Cd(Sn) and 150Nd(Sm)

The two Gamow-Teller (GT) branches connecting the double-beta decay partners (116Cd, 116Sn) and (150Nd, 150Sm) with the intermediate nuclei 116In and 150Pm are studied within a microscopic approach based on a deformed proton-neutron quasiparticle random-phase approximation built on a Skyrme selfconsistent mean field with pairing correlations and spin-isospin residual forces. The results are compared with the experimental GT strength distributions extracted from charge-exchange reactions. Combining the two branches, the nuclear matrix elements for the two-neutrino double-beta decay are evaluated and compared to experimental values derived from the measured half-lives.Comment: 10 pages, 16 figure

Asymmetric quantum cloning machines in any dimension

A family of asymmetric cloning machines for $N$-dimensional quantum states is introduced. These machines produce two imperfect copies of a single state that emerge from two distinct Heisenberg channels. The tradeoff between the quality of these copies is shown to result from a complementarity akin to Heisenberg uncertainty principle. A no-cloning inequality is derived for isotropic cloners: if $\pi_a$ and $\pi_b$ are the depolarizing fractions associated with the two copies, the domain in $(\sqrt{\pi_a},\sqrt{\pi_b})$-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. More generally, a no-cloning uncertainty relation is discussed, quantifying the impossibility of copying imposed by quantum mechanics. Finally, an asymmetric Pauli cloning machine is defined that makes two approximate copies of a quantum bit, while the input-to-output operation underlying each copy is a (distinct) Pauli channel. The class of symmetric Pauli cloning machines is shown to provide an upper bound on the quantum capacity of the Pauli channel of probabilities $p_x$, $p_y$ and $p_z$.Comment: 18 pages RevTeX, 3 Postscript figures; new discussion on no-cloning uncertainty relations, several corrections, added reference

Regulating Mobile Mental Health Apps

Mobile medical apps (MMAs) are a fast‐growing category of software typically installed on personal smartphones and wearable devices. A subset of MMAs are aimed at helping consumers identify mental states and/or mental illnesses. Although this is a fledgling domain, there are already enough extant mental health MMAs both to suggest a typology and to detail some of the regulatory issues they pose. As to the former, the current generation of apps includes those that facilitate self‐assessment or self‐help, connect patients with online support groups, connect patients with therapists, or predict mental health issues. Regulatory concerns with these apps include their quality, safety, and data protection. Unfortunately, the regulatory frameworks that apply have failed to provide coherent risk‐assessment models. As a result, prudent providers will need to progress with caution when it comes to recommending apps to patients or relying on app‐generated data to guide treatment

Non-abelian cubic vertices for higher-spin fields in anti-de Sitter space

We use the Fradkin-Vasiliev procedure to construct the full set of non-abelian cubic vertices for totally symmetric higher spin gauge fields in anti-de Sitter space. The number of such vertices is given by a certain tensor-product multiplicity. We discuss the one-to-one relation between our result and the list of non-abelian gauge deformations in flat space obtained elsewhere via the cohomological approach. We comment about the uniqueness of Vasiliev's simplest higher-spin algebra in relation with the (non)associativity properties of the gauge algebras that we classified. The gravitational interactions for (partially)-massless (mixed)-symmetry fields are also discussed. We also argue that those mixed-symmetry and/or partially-massless fields that are described by one-form connections within the frame-like approach can have nonabelian interactions among themselves and again the number of nonabelian vertices should be given by tensor product multiplicities.Comment: 30 pages, v2: minor corrections, reference adde