Readout error mitigated quantum state tomography tested on superconducting qubits

Abstract

Quantum technologies rely heavily on accurate control and reliable readout of quantum systems. Current experiments are limited by numerous sources of noise that can only be partially captured by simple analytical models and additional characterization of the noise sources is required. We test the ability of readout error mitigation to correct realistic noise found in systems composed of quantum two-level objects (qubits). To probe the limit of such methods, we designed a beyond-classical readout error mitigation protocol based on quantum state tomography (QST), which estimates the density matrix of a quantum system, and quantum detector tomography (QDT), which characterizes the measurement procedure. By treating readout error mitigation in the context of state tomography the method becomes largely readout mode-, architecture-, noise source-, and quantum state-independent. We implement this method on a superconducting qubit and evaluate the increase in reconstruction fidelity for QST. We characterize the performance of the method by varying important noise sources, such as suboptimal readout signal amplification, insufficient resonator photon population, off-resonant qubit drive, and effectively shortened $T_1$ and $T_2$ decay times. As a result, we identified noise sources for which readout error mitigation worked well, and observed decreases in readout infidelity by a factor of up to 30.

18 pages, 12 figures, corrections, title change and added additional information

References in corpus (14)

• Charge insensitive qubit design derived from the Cooper pair box
• Randomized Benchmarking of Quantum Gates
• Quantum Phases of Matter on a 256-Atom Programmable Quantum Simulator
• Experimental Quantum State Tomography of Optical Fields and Ultrafast Statistical Sampling
• Fault-tolerant quantum computation with high threshold in two dimensions
• Quantum Error Mitigation
• Hybrid quantum-classical algorithms and quantum error mitigation
• Measuring measurement
• Fundamental limits of quantum error mitigation
• Enhancing the Coherence of Superconducting Quantum Bits with Electric Fields
• Efficient tomography with unknown detectors
• Towards practical Quantum Credit Risk Analysis
• When quantum state tomography benefits from willful ignorance
• Efficient reconstruction, benchmarking and validation of cross-talk models in readout noise in near-term quantum devices

Cited by in corpus (7)

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• Benchmarking the quality of multiplexed qubit readout beyond assignment fidelity
• Nonequilibrium quantum thermometry with noncommutative system-bath couplings
• Mitigation of correlated readout errors without randomized measurements
• Superiority of Krylov shadow tomography in estimating quantum Fisher information: From bounds to exactness
• Limitations for adaptive quantum state tomography in the presence of detector noise
• Direct entanglement ansatz learning (DEAL) with ZNE on error-prone superconducting qubits