Entangled Macroscopic Quantum States in Two Superconducting Qubits
Abstract
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.
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Science
Volume 300 | Issue 5625
6 June 2003
6 June 2003
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American Association for the Advancement of Science.
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Received: 14 March 2003
Accepted: 30 April 2003
Published in print: 6 June 2003
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