dc measurements of macroscopic quantum levels in a superconducting qubit structure with a time-ordered meter

D. S. Crankshaw, K. Segall, D. Nakada, T. P. Orlando, L. S. Levitov, S. Lloyd, S. O. Valenzuela, N. Markovic, M. Tinkham, and K. K. Berggren
Phys. Rev. B 69, 144518 – Published 22 April 2004
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Abstract

dc measurements are made in a superconducting, persistent current qubit structure with a time-ordered meter. The persistent-current qubit has a double-well potential, with the two minima corresponding to magnetization states of opposite sign. Macroscopic resonant tunneling between the two wells is observed at values of energy bias that correspond to the positions of the calculated quantum levels. The magnetometer, a superconducting quantum interference device, detects the state of the qubit in a time-ordered fashion, measuring one state before the other. This results in a different meter output depending on the initial state, providing different signatures of the energy levels for each tunneling direction.

  • Received 1 October 2003

DOI:https://doi.org/10.1103/PhysRevB.69.144518

©2004 American Physical Society

Authors & Affiliations

D. S. Crankshaw, K. Segall, D. Nakada, and T. P. Orlando

  • Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

L. S. Levitov

  • Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

S. Lloyd

  • Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

S. O. Valenzuela, N. Markovic, and M. Tinkham

  • Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

K. K. Berggren

  • Massachusetts Institute of Technology Lincoln Laboratory, Lexington, Massachusetts 02420, USA

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Issue

Vol. 69, Iss. 14 — 1 April 2004

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