Low Temperature Physics: 38, 301 (2012); https://doi.org/10.1063/1.3699781 (10 pages)
Fizika Nizkikh Temperatur: Volume 38, Number 4 (April 2012), p. 382-395    ( to contents , go back )

Superposition of states in flux qubits with Josephson junction of ScS type (Review Article)

V.I. Shnyrkov1, A.A. Soroka2, A.M. Korolev3, and O.G. Turutanov1

1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: shnyrkov@ilt.kharkov.ua

2National Science Center "Kharkov Institute of Physics and Technology" 1 Academicheskaya St., Kharkov 61108, Ukraine

3Institute of Radio Astronomy NAS Ukraine, Krasnoznamennaya st., 4, Kharkov, 61002, Ukraine
pos Анотація:

Received Octouber 18, 2010

Abstract

The consequences of the transition to a quantum description of magnetic flux motion in the superconducting ring closed by the ScS Josephson junction are considered. The principal results on macroscopic quantum tunneling (MQT) of Bose condensate consisting of a macroscopically large number of Cooper electron pairs are reviewed. These phenomena are illustrated by the original data obtained from the study of MQT and coherent states in a modified flux qubit with energy level depletion ΔЕ01 ≈ 2∙10-23 J (ΔЕ01/h ≈ 30 GHz). The state superposition properties in the two-well potential and the issues associated with quantum measurements of local curvature of qubits’ superposition energy levels are analyzed.

PACS: 73.23.–b Electronic transport in mesoscopic systems;
PACS: 74.50.+r Tunneling phenomena; Josephsoneffects.

Key words: superposition of states, flux qubit, qutrit, SQUBID.

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