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arXiv:2405.18827 · Advanced Quantum Technologies

Device‐Independent Dimension Leakage Null Test on Qubits at Low Operational Cost

Tomasz Rybotycki, Tomasz Białecki, Josep Amengual i Batle, Adam Bednorz

Published Oct 8, 2024• 0 citations
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Abstract

Abstract A null test of the two‐level space of a qubit is constructed, which is both device independent and needs a small number of different experiments. Its feasibility is demonstrated on IBM Quantum, with most qubits failing the test by more than ten standard deviations. The robustness of the test against common technical imperfections, like decoherence and phase shifts, and supposedly negligible leakage, indicates that the origin of deviations is beyond known effects.

DOI
10.1002/qute.202400264

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We demonstrate a determinant dimension witness of a qubit space. Our test has a minimal number of independent parameters. We achieve it by mapping the Bloch sphere [Formula: see text]-rotation axis angle on the non-planar so-called Viviani curve. We ran our test on different platforms: IBM Quantum, IQM Resonance, and IonQ. Our investigations show that numerous qubits, especially from the newest IBM Heron family devices, fail the test by more than ten standard deviations. The nature of those deviations has no simple explanation as the test is robust against common imperfections.
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