Speed optimization of Josephson direct coupled logic

Logic design of Josephson network

Direct observation of Josephson capacitance.

The effective capacitance has been measured in the split Cooper-pair box (CPB) over its phase-gate bias plane. Our low-frequency reactive measurement scheme allows us to probe purely the capacitive susceptibility due to the CPB band structure. The data are quantitatively explained using parameters determined independently by spectroscopic means. In addition, we show in practice that the method ...

Electron Mobility Transistor Direct-Coupled FET Logic Inverters

The monolithic integration of enhancementand depletion-mode (Eand D-mode) high electron mobility transistors (HEMTs) lattice-matched to InP is of interest in the area of circuits for low power, high speed communications. When compared to circuits implemented in depletion-mode @-mode) only technology, circuits implemented in ED-mode technology enjoy a number of advantages. D-mode only circuits r...

Dynamic behavior of Josephson-coupled layered structures.

Coherent manipulation of coupled Josephson charge qubits

We have analyzed and measured the quantum coherent dynamics of a circuit containing two-coupled superconducting charge qubits. Each qubit is based on a Cooper pair box connected to a reservoir electrode through a Josephson junction. Two qubits are coupled electrostatically by a small island overlapping both Cooper pair boxes. Quantum state manipulation of the qubit circuit is done by applying n...