Spectral Quantum Tomography

Abstract

We introduce spectral quantum tomography, a simple method to extract the eigenvalues of a noisy few-qubit gate, represented by a trace-preserving superoperator, in a SPAM-resistant fashion, using low resources in terms of gate sequence length. The eigenvalues provide detailed gate information, supplementary to known gate-quality measures such as the gate fidelity, and can be used as a gate diagnostic tool. We apply our method to one- and two-qubit gates on two different superconducting systems available in the cloud, namely the QuTech Quantum Infinity and the IBM Quantum Experience. We discuss how cross-talk, leakage and non-Markovian errors affect the eigenvalue data.

13 pages, 6 figures v2: various minor changes, close to accepted version

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Cited by in corpus (13)

• Gate Set Tomography
• Non-Markovian Quantum Process Tomography
• A Practical Introduction to Benchmarking and Characterization of Quantum Computers
• Filling up complex spectral regions through non-Hermitian disordered chains
• Spectral estimation for Hamiltonians: a comparison between classical imaginary-time evolution and quantum real-time evolution
• Emergence of noise-induced barren plateaus in arbitrary layered noise models
• Consistency testing for robust phase estimation
• Estimation of correlations and non-separability in quantum channels via unitarity benchmarking
• Quantum process tomography of continuous-variable gates using coherent states
• Model-Independent Simulation Complexity of Complex Quantum Dynamics
• Deformation quantization and the tomographic representation of quantum fields
• A simple formulation of no-cloning and no-hiding that admits efficient and robust verification
• Theory of quantum error mitigation for non-Clifford gates