Showing papers by "Yoseph Imry published in 1994"
TL;DR: In this paper, the lifetime of a quantum dot is calculated as a function of energy, disorder, and dot size, and the number of discrete levels is of the order of 5-20 in typical experiments, though such dots may contain thousands of electrons.
Abstract: The quasi-particle lifetime is calculated for electrons in a quantum dot as a function of energy, disorder, and dot size. As a result of electron-electron interaction, the spectrum is discrete only in close vicinity of the Fermi level. In the strongly diffusive case, levels farther than the Thouless energy (inverse diffusion time across the dot) from the Fermi level are broadened by the interaction beyond the average level spacing and merge to form a continuous spectrum. The number of discrete levels is hence of the order of 5-20 in typical experiments though such dots may contain thousands of electrons. For less disordered and ballistics dots, the number of discrete levels is of the order of the square root of the number of electrons in the dot.
73 citations
TL;DR: In this article, a general formulation of the loss of phase coherence between two partial waves, leading to the dephasing of their interference, is given, and stringent conditions for observing the discrete spectrum of such a dot, in agreement with recent experiments.
Abstract: A general formulation will be given of the loss of phase coherence between two partial waves, leading to the dephasing of their interference. This is due to inelastic scattering from the 'environment' (which is a different set of degrees of freedom that the waves are coupled with). For a conduction electron, the other electrons ('Fermi sea') are often the dominant environment of this type. Coulomb interactions with the latter are, especially at lower dimensions, the most important dephasing mechanism. It will be shown how this picture yields rather straightforwardly the very non-trivial results of Altshuler, Aronov and Khmelnitskii in one and two dimensions, in the diffusive case. Subtleties associated with divergences that have to be subtracted will be discussed. These results are known to agree well with experiments. As a new application of the above ideas, the dephasing in a zero-dimensional quantum dot will be briefly considered. This will lead to stringent conditions for observing the discrete spectrum of such a dot, in agreement with recent experiments. The crossover at low temperatures in small wires from one- to zero-dimensional behaviour will be shown to 'rescue' the Landau Fermi-liquid theory from being violated because of the T2/3 behaviour of the 1D dephasing rate. After clarifying the relationship between the e-e scattering rate and the dephasing rate, the connection with the former will be made, including the ballistic regime.
9 citations
TL;DR: In this article, the authors review developments in quasi particle level response to external perturbations, correlated tunneling through isolated impurities, the persistent current problem, and mesoscopic effects related to superconductivity.
5 citations
TL;DR: It is shown that the pair-transfer process is effective in reducing the Coulomb repulsion even in situations where the second band is very narrow and possesses by itself a very large repulsion.
Abstract: The screening and renormalization of the Coulomb repulsion in the conduction band of a two-band model are considered It is shown that when the second band lies above the conduction band and it is empty at low temperatures, the transfer of pairs of charge carriers between the two bands is the relevant interband process for reducing the Coulomb repulsion in the conduction band By considering a two-band situation arising from the hybridization of the conduction band with shallow impurity states having a large intrasite repulsion, it is shown that the pair-transfer process is effective in reducing the Coulomb repulsion even in situations where the second band is very narrow and possesses by itself a very large repulsion The implications for enhanced pairing in systems with the appropriate band structure or in those near the metal-insulator transition caused by doping, are discussed
3 citations