Measuring charge-based quantum bits by a superconducting single-electron transistor

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2003
Major/Subject
Mcode
Degree programme
Language
en
Pages
020506/1-4
Series
Physical Review B, Volume 68, Issue 2
Abstract
Single-electron transistors have been proposed to be used as a read-out device for Cooper pair charge qubits. Here we show that a coupled superconducting transistor at a threshold voltage is much more effective in measuring the state of a qubit than a normal-metal transistor at the same voltage range. The effect of the superconducting gap is to almost completely block the current through the transistor when the qubit is in the logical state 1, compared to the mere diminishment of the current in the normal-metal case. The time evolution of the system is solved when the measuring device is driven out of equilibrium, the effect of higher-order contributions is examined and the setting is analyzed numerically for parameters accessible by lithographic aluminum structures.
Description
Keywords
superconductors, single-electron transistors, charge-based quantum bits
Other note
Citation
Kinnunen, J. & Törmä, P. & Pekola, Jukka. 2003. Measuring charge-based quantum bits by a superconducting single-electron transistor. Physical Review B. Volume 68, Issue 2. 020506/1-4. ISSN 1098-0121 (printed). DOI: 10.1103/physrevb.68.020506.