971 research outputs found
Bloch inductance in small-capacitance Josephson junctions
We show that the electrical impedance of a small-capacitance Josephson
junction includes besides the capacitive term also an inductive
term . Similar to the known Bloch capacitance , the Bloch
inductance also depends periodically on the quasicharge , and its
maximum value achieved at always exceeds the value of
the Josephson inductance of this junction at fixed . The
effect of the Bloch inductance on the dynamics of a single junction and a
one-dimensional array is described.Comment: 5 pages incl. 3 fig
An Approach to Automatic Indexing of Scientific Publications in High Energy Physics for Database SPIRES HEP
We introduce an approach to automatic indexing of e-prints based on a
pattern-matching technique making extensive use of an Associative Patterns
Dictionary (APD), developed by us. Entries in the APD consist of natural
language phrases with the same semantic interpretation as a set of keywords
from a controlled vocabulary. The method also allows to recognize within
e-prints formulae written in TeX notations that might also appear as keywords.
We present an automatic indexing system, AUTEX, which we have applied to
keyword index e-prints in selected areas in high energy physics (HEP) making
use of the DESY-HEPI thesaurus as a controlled vocabulary.Comment: 23 pages, 4 figure
Sensitivity and Linearity of Superconducting Radio-Frequency Single-Electron Transistors: Effects of Quantum Charge Fluctuations
We have investigated the effects of quantum fluctuations of quasiparticles on
the operation of superconducting radio-frequency single-electron transistors
(RF-SETs) for large values of the quasiparticle cotunneling parameter
, where and are the Josephson and charging
energies. We find that for , subgap RF-SET operation is still
feasible despite quantum fluctuations that renormalize the SET charging energy
and wash out quasiparticle tunneling thresholds. Surprisingly, such RF-SETs
show linearity and signal-to-noise ratio superior to those obtained when
quantum fluctuations are weak, while still demonstrating excellent charge
sensitivity.Comment: Submitted to Phys. Rev. Let
Nonequilibrium and Parity Effects in the Tunneling Conductance of Ultrasmall Superconducting Grains
Recent experiment on the tunneling spectra of ultrasmall superconducting
grains revealed an unusual structure of the lowest differential conductance
peak for grains in the odd charging states. We explain this behavior by
nonequilibrium ``gapless'' excitations associated with different energy levels
occupied by the unpaired electron. These excitations are generated by inelastic
cotunneling.Comment: 4 pages, 2 .eps figures include
FQHE interferometers in strong tunneling regime. The role of compactness of edge fields
We consider multiple-point tunneling in the interferometers formed between
edges of electron liquids with in general different filling factors in the
regime of the Fractional Quantum Hall effect (FQHE). We derive an effective
matrix Caldeira-Leggett models for the multiple tunneling contacts connected by
the chiral single-mode FQHE edges. It is shown that the compactness of the Wen-
Fr\"ohlich chiral boson fields describing the FQHE edge modes plays a crucial
role in eliminating the spurious non-locality of the electron transport
properties of the FQHE interferometers arising in the regime of strong
tunneling.Comment: 5 page
Resonant tunneling through a macroscopic charge state in a superconducting SET transistor
We predict theoretically and observe in experiment that the differential
conductance of a superconducting SET transistor exhibits a peak which is a
complete analogue in a macroscopic system of a standard resonant tunneling peak
associated with tunneling through a single quantum state. In particular, in a
symmetric transistor, the peak height is universal and equal to . Away from the resonance we clearly observe the co-tunneling current
which in contrast to the normal-metal transistor varies linearly with the bias
voltage.Comment: 11 pages, 3 figures, Fig. 1 available upon request from the first
autho
Correlated transport of FQHE quasiparticles in a double-antidot system
We have calculated the linear conductance associated with tunneling of
individual quasiparticles of primary quantum Hall liquids with filling factors
through a system of two antidots in series. On-site Coulomb
interaction simulates the Fermi exclusion and makes the quasiparticle dynamics
similar to that of tunneling electrons. The liquid edges serve as the
quasiparticle reservoirs, and also create the dissipation mechanism for
tunneling between the antidots. In the regime of strong dissipation, the
conductance should exhibit resonant peaks of unusual form and a width
proportional to the quasiparticle interaction energy . In the weakly-damped
regime, the shape of the resonant conductance peaks reflects coherent tunnel
coupling of the antidots. The Luttinger-liquid singularity in the rates of
quasiparticle tunneling to/from the liquid edges manifests itself as an
additional weak resonant structure in the conductance curves.Comment: 9 pages including 5 figure
Resistively-shunted superconducting quantum point contacts
We have studied the Josephson dynamics of resistively-shunted ballistic
superconducting quantum point contacts at finite temperatures and arbitrary
number of conducting modes. Compared to the classical Josephson dynamics of
tunnel junctions, dynamics of quantum point contacts exhibits several new
features associated with temporal fluctuations of the Josephson potential
caused by fluctuations in the occupation of the current-carrying Andreev
levels.Comment: 5 pages, RevTex, 3 postscript figures include
AC Josephson effect and resonant Cooper pair tunneling emission of a Cooper Pair Transistor
We measure the high-frequency emission of a single Cooper pair
transistor(SCPT) in the regime where transport is only due to tunneling of
Cooper pairs. This is achieved by coupling on-chip the SCPT to a
superconductor-insulator-superconductor junction and by measuring the photon
assisted tunneling current of quasiparticles across the junction. This
technique allows a direct detection of the AC Josephson effect of the SCPT and
provides evidence of Landau-Zener transitions for proper gate voltage. The
emission in the regime of resonant Cooper pair tunneling is also investigated.
It is interpreted in terms of transitions between charge states coupled by the
Josephson effect.Comment: Revtex4, 5 pages, 4 figures, final versio
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