Quantum leakage detection using a model-independent dimension witness

Abstract

Users of quantum computers must be able to confirm they are indeed functioning as intended, even when the devices are remotely accessed. In particular, if the Hilbert space dimension of the components are not as advertised -- for instance if the qubits suffer leakage -- errors can ensue and protocols may be rendered insecure. We refine the method of delayed vectors, adapted from classical chaos theory to quantum systems, and apply it remotely on the IBMQ platform -- a quantum computer composed of transmon qubits. The method witnesses, in a model-independent fashion, dynamical signatures of higher-dimensional processes. We present evidence, under mild assumptions, that the IBMQ transmons suffer state leakage, with a $p$ value no larger than $5\times 10^{-4}$ under a single qubit operation. We also estimate the number of shots necessary for revealing leakage in a two-qubit system.

arXiv comment11 pages, 5 figures

References in corpus (30)

• Charge insensitive qubit design derived from the Cooper pair box
• Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing
• Simple pulses for elimination of leakage in weakly nonlinear qubits
• High-fidelity quantum logic gates using trapped-ion hyperfine qubits
• High-fidelity two-qubit quantum logic gates using trapped calcium-43 ions
• The European Quantum Technologies Roadmap
• Efficient Z-Gates for Quantum Computing
• Procedure for systematically tuning up crosstalk in the cross resonance gate
• Testing the Hilbert space dimension
• Device-independent tests of classical and quantum dimensions
• Operational Markov condition for quantum processes
• Fast quantum logic gates with trapped-ion qubits
• Analytic control methods for high fidelity unitary operations in a weakly nonlinear oscillator
• Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit
• Self-Consistent Measurement and State Tomography of an Exchange-Only Spin Qubit
• Random Quantum Circuits and Pseudo-Random Operators: Theory and Applications
• Quantification and Characterization of Leakage Errors
• A lower bound on the dimension of a quantum system given measured data
• Experimental Device-independent Tests of Classical and Quantum Dimensions
• Random Quantum Operations
• Convergence Conditions for Random Quantum Circuits
• Multiparty Delegated Quantum Computing
• Characterization of Leakage Errors via Randomized Benchmarking
• Gate-error analysis in simulations of quantum computers with transmon qubits
• Maximum violations of the quantum-witness equality
• Witnessing irreducible dimension
• Assessing dimensions from evolution
• Certifying an irreducible 1024-dimensional photonic state using refined dimension witnesses
• Structure of temporal correlations of a qubit
• Two-Qubit Pulse Gate for the Three-Electron Double Quantum Dot Qubit

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• Model-Independent Simulation Complexity of Complex Quantum Dynamics
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