187,134 research outputs found
Topological insulators are tunable waveguides for hyperbolic polaritons
Layered topological insulators, for example, BiSe are optically
hyperbolic materials in a range of THz frequencies. Such materials possess
deeply subdiffractional, highly directional collective modes: hyperbolic
phonon-polaritons. In thin crystals the dispersion of such modes is split into
discrete subbands and is strongly influenced by electron surface states. If the
surface states are doped, then hybrid collective modes result from coupling of
the phonon-polaritons with surface plasmons. The strength of the hybridization
can be controlled by an external gate that varies the chemical potential of the
surface states. Momentum-dependence of the plasmon-phonon coupling leads to a
polaritonic analog of the Goos-H\"anchen effect. Directionality of the
polaritonic rays and their tunable Goos-H\"anchen shift are observable via THz
nanoimaging.Comment: 12 pages, 7 figure
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Bioinspired Multifunctional Anti-icing Hydrogel
The recent anti-icing strategies in the state of the art mainly focused on three aspects: inhibiting ice nucleation, preventing ice propagation, and decreasing ice adhesion strength. However, it is has proved difficult to prevent ice nucleation and propagation while decreasing adhesion simultaneously, due to their highly distinct, even contradictory design principles. In nature, anti-freeze proteins (AFPs) offer a prime example of multifunctional integrated anti-icing materials that excel in all three key aspects of the anti-icing process simultaneously by tuning the structures and dynamics of interfacial water. Here, inspired by biological AFPs, we successfully created a multifunctional anti-icing material based on polydimethylsiloxane-grafted polyelectrolyte hydrogel that can tackle all three aspects of the anti-icing process simultaneously. The simplicity, mechanical durability, and versatility of these smooth hydrogel surfaces make it a promising option for a wide range of anti-icing applications
The Cauchy problem for the Pavlov equation
Commutation of multidimensional vector fields leads to integrable nonlinear
dispersionless PDEs arising in various problems of mathematical physics and
intensively studied in the recent literature. This report is aiming to solve
the scattering and inverse scattering problem for integrable dispersionless
PDEs, recently introduced just at a formal level, concentrating on the
prototypical example of the Pavlov equation, and to justify an existence
theorem for global bounded solutions of the associated Cauchy problem with
small data.Comment: In the new version the analytical technique was essentially revised.
The previous version contained a wrong statement about the solvability of the
inverse problem for large data. This problem remains ope
Development of a new instrument for direct skin friction measurements
A device developed for the direct measurement of wall shear stress generated by flows is described. Simple and symmetric in design with optional small moving mass and no internal friction, the features employed in the design eliminate most of the difficulties associated with the traditional floating element balances. The device is basically small and can be made in various sizes. Vibration problems associated with the floating element skin friction balances were found to be minimized due to the design symmetry and optional damping provided. The design eliminates or reduces the errors associated with conventional floating element devices: such as errors due to gaps, pressure gradient, acceleration, heat transfer, and temperature change. The instrument is equipped with various sensing systems and the output signal is a linear function of the wall shear stress. Dynamic measurements could be made in a limited range and measurements in liquids could be performed readily. Measurement made in the three different tunnels show excellent agreement with data obtained by the floating element devices and other techniques
The Emergence of Superconducting Systems in Anti-de Sitter Space
In this article, we investigate the mathematical relationship between a (3+1)
dimensional gravity model inside Anti-de Sitter space , and a (2+1)
dimensional superconducting system on the asymptotically flat boundary of (in the absence of gravity). We consider a simple case of the Type II
superconducting model (in terms of Ginzburg-Landau theory) with an external
perpendicular magnetic field . An interaction potential is introduced
within the Lagrangian system. This provides more flexibility within the model,
when the superconducting system is close to the transition temperature .
Overall, our result demonstrates that the two Ginzburg-Landau differential
equations can be directly deduced from Einstein's theory of general relativity.Comment: 10 pages, 2 figure
Dressed Qubits
Inherent gate errors can arise in quantum computation when the actual system
Hamiltonian or Hilbert space deviates from the desired one. Two important
examples we address are spin-coupled quantum dots in the presence of spin-orbit
perturbations to the Heisenberg exchange interaction, and off-resonant
transitions of a qubit embedded in a multilevel Hilbert space. We propose a
``dressed qubit'' transformation for dealing with such inherent errors. Unlike
quantum error correction, the dressed qubits method does not require additional
operations or encoding redundancy, is insenstitive to error magnitude, and
imposes no new experimental constraints.Comment: Replaced with published versio
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