Bloch inductance in small-capacitance Josephson junctions

We show that the electrical impedance of a small-capacitance Josephson junction includes besides the capacitive term $-i/\omega C_B$ also an inductive term $i\omega L_B$. Similar to the known Bloch capacitance $C_B(q)$, the Bloch inductance $L_B(q)$ also depends periodically on the quasicharge $q$, and its maximum value achieved at $q=e (\textrm{mod} 2e)$ always exceeds the value of the Josephson inductance of this junction $L_J(\phi)$ at fixed $\phi=0$. 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

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 $\alpha=8E_{J}/E_{c}$, where $E_{J}$ and $E_{c}$ are the Josephson and charging energies. We find that for $\alpha>1$, 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

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

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 $e^2/2\pi \hbar$. 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

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

Coulomb blockade in superconducting quantum point contacts

Amplitude of the Coulomb blockade oscillations is calculated for a single-mode Josephson junction with arbitrary electron transparency $D$. It is shown that the Coulomb blockade is suppressed in ballistic junctions with $D\to 1$. The suppression is described quantitatively as the Landau-Zener transition in imaginary time.Comment: 5 pages, 3 figures include

Coulomb Charging Effects for Finite Channel Number

We consider quantum fluctuations of the charge on a small metallic grain caused by virtual electron tunneling to a nearby electrode. The average electron number and the effective charging energy are determined by means of perturbation theory in the tunneling Hamiltonian. In particular we discuss the dependence of charging effects on the number N of tunneling channels. Earlier results for N>>1 are found to be approached rather rapidly with increasing N.Comment: 6 pages, 5 figure