Search results for "TUNNEL"
showing 10 items of 576 documents
Noise induced effects in overdamped Josephson junction in the presence of colored noise
2007
We analyze the role of the correlated fluctuations, with a correlation time τc, in the dynamics of an overdamped Josephson junction in the presence of a periodic driving signal.
Gd-based single-ion magnets with tunable magnetic anisotropy: Molecular design of spin qubits
2012
et al.
Asymptotic and Numerical Studies of Resonant Tunneling in 2D-Waveguides for Electrons of Small Energy
2021
Chapter 5 is devoted to asymptotic studies of electron resonant tunneling in a two-dimensional waveguide with two narrows. The narrow diameter plays the role of a small parameter. The asymptotics of basic characteristics of resonant tunneling are presented for electrons with energy between the first and the second thresholds. Moreover, the asymptotics results are compared with numerical ones obtained by approximate calculation of the scattering matrix.
Momentum partition between constituents of exotic atoms during laser-induced tunneling ionization
2015
The tunneling ionization of exotic atoms such as muonic hydrogen, muonium, and positronium in a strong laser field of circular polarization is investigated, taking into account the impact of the motion of the center of mass on the the tunneling ionization dynamics. The momentum partition between the ionization products is deduced. The effect of the center-of-mass motion for the momentum distribution of the ionization components is determined. The effect scales with the ratio of the electron (muon) to the atomic core masses and is nonnegligible for exotic atoms, while being insignificant for common atoms. It is shown that the electron (muon) momentum shift during the under-the-barrier motion…
Electron–phonon interaction in a thin Al–Mn film
2006
Abstract Aluminum doped with manganese is an interesting novel material with applications in normal metal–insulator–superconductor (NIS) tunnel junction devices and transition-edge sensors at sub-Kelvin temperatures. We have studied the electron–phonon (e–p) coupling in a thin aluminum film doped with 1% manganese, with a measuring technique based on DC hot-electron effect. The electron temperature was measured with the help of symmetric normal metal–insulator–superconductor tunnel-junction pairs (SINIS-thermometers). Measurements show that the temperature dependence of the e–p interaction is not consistent with existing theories for disordered metals, but follows a higher power law.
Description of sub-barrier heavy ion fusion in a semiclassical quantum tunneling model
1996
In this paper we apply the semiclassical method based on the Feynman path integral formalism to sub-barrier fusion of heavy nuclei. Cross sections are calculated and compared to experimental data and to coupled-channel calculations for different mass systems: 32S124Mg, 58Ni164Ni, and 16O1208Pb. The semiclassical method and coupled-channel calculations give comparable results. It is found that the coupling produces a renormalization of the barrier that is responsible for the enhancement of sub-barrier fusion cross sections and a dissipative force along the classical tunneling path.
Detection of the optical magnetic field by circular symmetry plasmons
2000
We report on the influence of coating a sharpened optical fiber tip with Au when observing nanofabricated dielectric structures with a Photon Scanning Tunneling Microscope (PSTM) in constant-height mode. For well-defined incident wavelengths and coating thicknesses, we found that such tips detect the distribution of the magnetic field associated with the optical wave in the near-field zone. A simple tip model indicates that this phenomenon is related to the excitation of circular symmetry plasmons in Au coated tips.
Coherent control via weak measurements in P31 single-atom electron and nuclear spin qubits
2018
The understanding of weak measurements and interaction-free measurements has greatly expanded the conceptual and experimental toolbox to explore the quantum world. Here we demonstrate single-shot variable-strength weak measurements of the electron and nuclear spin states of a P31 single-atom donor in silicon. We first show how the partial collapse of the nuclear spin due to measurement can be used to coherently rotate the spin to a desired pure state. We explicitly demonstrate that phase coherence is preserved with high fidelity throughout multiple sequential single-shot weak measurements and that the partial state collapse can be reversed. Second, we use the relation between measurement st…
Simultaneous observation of light localization and confinement in near-field optics
2001
We report on the observation, in direct space, of both light localization and confinement effects near lithographically designed structures. The sample is observed in the optical near-field zone with a Photon Scanning Tunneling Microscope (PSTM). Several patterns composed of a few periods of TiO2 dots, arranged as a hexagonal lattice, have been investigated. When the central dot of the pattern is removed, a phenomenon of light localization above the vacancy can be observed in the PSTM image. The occurrence of this phenomenon can be related to the variation of the electromagnetic local density of state.
One and two dimensional tunnel junction arrays in weak Coulomb blockade regime-absolute accuracy in thermometry
1999
We have investigated one and two dimensional (1D and 2D) arrays of tunnel junctions in partial Coulomb blockade regime. The absolute accuracy of the Coulomb blockade thermometer is influenced by the external impedance of the array, which is not the same in the different topologies of 1D and 2D arrays. We demonstrate, both by experiment and by theoretical calculations in simple geometries, that the 1D structures are better in this respect. Yet in both 1D and 2D, the influence of the environment can be made arbitrarily small by making the array sufficiently large.