Measurement and on-chip control of a niobium persistent current qubit
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53278793-MIT.pdf
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Full printable version
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14.1 MB
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Checksum (MD5)
953b685edef3b2d0bf43de6b7e98fdf4
Author(s)
Crankshaw, Donald S. (Donald Shane), 1974-
Advisor(s)
Terry P. Orlando.
Date Issued
2003
Publisher
Massachusetts Institute of Technology
Abstract
The persistent current qubit is a superconducting ring interrupted by three Josephson junctions. Its two quantum states have circulating currents in opposite directions which can be measured by a dc SQUID magnetometer. This work examines a persistent current qubit fabricated in niobium, using Lincoln Laboratory's DPARTS process. Measurements of the niobium qubit show a promisingly high subgap resistance, demonstrate discrete energy levels, and give good estimates of the qubit parameters as fabricated. Although the variances on the qubit parameters are large, it is possible to design a qubit whose parameters are in the quantum regime. Additionally, we show how the qubit can be integrated with on-chip electronics while taking into account decoherence. A dc SQUID oscillator has been designed which can deliver an oscillating field at 10 GHz without reducing the decoherence time below 1 microsecond. The oscillator is shown to deliver power to the measurement device, although the qubit rotation has not yet been observed.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (p. 203-208).
Subjects
Electrical Engineering and Computer Science.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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