Testing quantum computers with the protocol of quantum state matching

Abstract

The presence of noise in quantum computers hinders their effective operation. Even though quantum error correction can theoretically remedy this problem, its practical realization is still a challenge. Testing and benchmarking noisy, intermediate-scale quantum (NISC) computers is therefore of high importance. Here, we suggest the application of the so-called quantum state matching protocol for testing purposes. This protocol was originally proposed to determine if an unknown quantum state falls in a prescribed neighborhood of a reference state. We decompose the unitary specific to the protocol and construct the quantum circuit implementing one step of the dynamics for different characteristic parameters of the scheme and present test results for two different IBM quantum computers. By comparing the experimentally obtained relative frequencies of success to the ideal success probability with a maximum statistical tolerance, we discriminate statistical errors from device specific ones. For the characterization of noise, we also use the fact that while the output of the ideal protocol is insensitive to the internal phase of the input state, the actual implementation may lead to deviations. For systematically varied inputs we find that the device with the smaller quantum volume performs better on our tests than the one with larger quantum volume, while for random inputs they show a more similar performance.

References in corpus (23)

• Quantum state engineering with Josephson-junction devices
• Noisy intermediate-scale quantum (NISQ) algorithms
• Randomized Benchmarking of Quantum Gates
• Robust randomized benchmarking of quantum processes
• Time Optimal Control in Spin Systems
• Validating quantum computers using randomized model circuits
• Quantum optimization using variational algorithms on near-term quantum devices
• Experimental Comparison of Two Quantum Computing Architectures
• Benchmarking an 11-qubit quantum computer
• Scalable Noise Estimation with Random Unitary Operators
• Characterizing Quantum Gates via Randomized Benchmarking
• Optimal Quantum Circuits for General Two-Qubit Gates
• Optimal Creation of Entanglement Using a Two--Qubit Gate
• A universal quantum circuit for two-qubit transformations with three CNOT gates
• Measuring the Capabilities of Quantum Computers
• Detector Tomography on IBM 5-qubit Quantum Computers and Mitigation of Imperfect Measurement
• Benchmarking gate-based quantum computers
• An Arbitrary Two-qubit Computation In 23 Elementary Gates
• Re-examining the quantum volume test: Ideal distributions, compiler optimizations, confidence intervals, and scalable resource estimations
• An Introduction to Cartan's KAK Decomposition for QC Programmers
• Cartan Decomposition of SU(2^n), Constructive Controllability of Spin systems and Universal Quantum Computing
• Scalable Benchmarks for Gate-Based Quantum Computers
• Quantum state matching of qubits via measurement-induced nonlinear transformations