Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Originally published in Science Express on 15 May 2003
Science 6 June 2003:
Vol. 300. no. 5625, pp. 1548 - 1550
DOI: 10.1126/science.1084528
Prev | Table of Contents | Next

Reports

Entangled Macroscopic Quantum States in Two Superconducting Qubits

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, F. C. Wellstood

We present spectroscopic evidence for the creation of entangled macroscopic quantum states in two current-biased Josephson-junction qubits coupled by a capacitor. The individual junction bias currents are used to control the interaction between the qubits by tuning the energy level spacings of the junctions in and out of resonance with each other. Microwave spectroscopy in the 4 to 6 gigahertzrange at 20 millikelvin reveals energy levels that agree well with theoretical results for entangled states. The single qubits are spatially separate, and the entangled states extend over the 0.7-millimeter distance between the two qubits.

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

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Response to Comment on "Multipartite Entanglement Among Single Spins in Diamond".
P. Neumann, N. Mizuochi, F. Rempp, P. Hemmer, H. Watanabe, S. Yamasaki, V. Jacques, T. Gaebel, F. Jelezko, and J. Wrachtrup (2009)
Science 323, 1169d
   Abstract »    Full Text »    PDF »
Quantum Coherent Tunable Coupling of Superconducting Qubits.
A. O. Niskanen, K. Harrabi, F. Yoshihara, Y. Nakamura, S. Lloyd, and J. S. Tsai (2007)
Science 316, 723-726
   Abstract »    Full Text »    PDF »
Solid-State Qubits with Current-Controlled Coupling.
T. Hime, P. A. Reichardt, B. L. T. Plourde, T. L. Robertson, C.-E. Wu, A. V. Ustinov, and J. Clarke (2006)
Science 314, 1427-1429
   Abstract »    Full Text »    PDF »
Measurement of the entanglement of two superconducting qubits via state tomography..
M. Steffen, M. Ansmann, R. C. Bialczak, N. Katz, E. Lucero, R. McDermott, M. Neeley, E. M. Weig, A. N. Cleland, and J. M. Martinis (2006)
Science 313, 1423-1425
   Abstract »    Full Text »    PDF »
Quantum Dynamics of a d-Wave Josephson Junction.
T. Bauch, T. Lindstrom, F. Tafuri, G. Rotoli, P. Delsing, T. Claeson, and F. Lombardi (2006)
Science 311, 57-60
   Abstract »    Full Text »    PDF »
Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit.
W. D. Oliver, Y. Yu, J. C. Lee, K. K. Berggren, L. S. Levitov, and T. P. Orlando (2005)
Science 310, 1653-1657
   Abstract »    Full Text »    PDF »
Simultaneous State Measurement of Coupled Josephson Phase Qubits.
R. McDermott, R. W. Simmonds, M. Steffen, K. B. Cooper, K. Cicak, K. D. Osborn, S. Oh, D. P. Pappas, and J. M. Martinis (2005)
Science 307, 1299-1302
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)