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arXiv · 1905.00271

Fast high fidelity quantum non-demolition qubit readout via a non-perturbative cross-Kerr coupling

R. Dassonneville·T. Ramos·V. Milchakov·L. Planat·É. Dumur·F. Foroughi·J. Puertas·S. Leger·K. Bharadwaj·J. Delaforce·C. Naud·W. Hasch-Guichard·J. J. García-Ripoll·N. Roch·O. Buisson
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Abstract

Qubit readout is an indispensable element of any quantum information processor. In this work, we experimentally demonstrate a non-perturbative cross-Kerr coupling between a transmon and a polariton mode which enables an improved quantum non-demolition (QND) readout for superconducting qubits. The new mechanism uses the same experimental techniques as the standard QND qubit readout in the dispersive approximation, but due to its non-perturbative nature, it maximizes the speed, the single-shot fidelity and the QND properties of the readout. In addition, it minimizes the effect of unwanted decay channels such as the Purcell effect. We observed a single-shot readout fidelity of 97.4% for short 50 ns pulses, and we quantified a QND-ness of 99% for long measurement pulses with repeated single-shot readouts.

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R. Dassonneville, T. Ramos, V. Milchakov, L. Planat, É. Dumur, F. Foroughi, J. Puertas, S. Leger, K. Bharadwaj, J. Delaforce, C. Naud, W. Hasch-Guichard, J. J. García-Ripoll, N. Roch, O. Buisson. 2019-05-01. Fast high fidelity quantum non-demolition qubit readout via a non-perturbative cross-Kerr coupling. https://doi.org/10.1103/physrevx.10.011045

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