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Updated: Jun 8, 2026

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
Quantum nondemolition measurement of a superconducting qubit in the weakly projective regime
T Picot1, R Schouten, C J P M Harmans
1Kavli Institute of Nanoscience, Delft University of Technology, Post Office Box 5046, 2600GA Delft, The Netherlands.
Abstract:
Quantum state detectors based on switching of hysteretic Josephson junctions biased close to their critical current are simple to use but have strong backaction. We show that the backaction of a dc-switching detector can be considerably reduced by limiting the switching voltage and using a fast cryogenic amplifier, such that a single readout can be completed within 25 ns at a repetition rate of 1 MHz without loss of contrast. Based on a sequence of two successive readouts we show that the measurement has a clear quantum nondemolition character, with a QND fidelity of 75%.
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