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Updated: Jul 19, 2026

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
State tomography of capacitively shunted phase qubits with high fidelity
Matthias Steffen1, M Ansmann, R McDermott
1Department of Physics and California Nanosystems Institute, University of California, Santa Barbara, CA 93106, USA.
Abstract:
We introduce a new design concept for superconducting phase quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstration of quantum state tomography with superconducting qubits using single-shot measurements.
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