Measurement and on-chip control of a niobium persistent current qubit

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.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Crankshaw, Donald S. (Donald Shane), 1974-

Advisor dc:contributor.advisor

• Terry P. Orlando.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/28278

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/28278