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Submitted on March 13, 2003
Accepted on April 30, 2003
Entangled Macroscopic Quantum States in Two Superconducting Qubits
A. J. Berkley 1*,H. Xu 1,R. C. Ramos 1,M. A. Gubrud 1,F. W. Strauch 1,P. R. Johnson 1,J. R. Anderson 1,A. J. Dragt 1,C. J. Lobb 1,F. C. Wellstood 1
1 Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742, USA.
* To whom correspondence should be addressed. E-mail: berkley{at}physics.umd.edu.
We present spectroscopic evidence for the creation of entangledmacroscopic quantum states in two current-biased Josephson-junctionqubits coupled by a capacitor. The individual junction biascurrents are used to control the interaction between the qubitsby tuning the energy level spacings of the junctions in andout of resonance with each other. Microwave spectroscopy inthe 4-6 GHz range at 20 mK reveals energy levels which agreewell with theoretical results for entangled states. The singlequbits are spatially separate and the entangled states extendover the 0.7 mm distance between the two qubits.
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LETTERS
Antoni Wójcik;, A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood (29 August 2003) Science301 (5637), 1183.
[DOI: 10.1126/science.301.5637.1183] |Full Text »|PDF »
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