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QI: Fachverband Quanteninformation

QI 30: Quantum Algorithms

QI 30.7: Talk

Thursday, March 9, 2023, 16:15–16:30, B305

Variational quantum amplitude estimation on noisy quantum processors — •Tobias Nauck, Thomas Wellens, and Andreas Ketterer — Fraunhofer Institut für Angewandte Festkörperphysik

The quantum amplitude estimation algorithm provides a quadratic speedup over classical Monte Carlo methods in the task of approximately evaluating integrals. This maximum speedup can, however, only be achieved with quantum circuits of exponentially growing depths which is unfeasible on noisy intermediate-scale quantum processors. In order to tackle the problem of impractically large circuit depths, we develop a hybrid algorithm that approximates circuits with depths exceeding a predefined threshold using a classical variational approximation. To do so, we maximize the fidelty between the invovled circuits and an appropriate variational circuit of low depth on neighboring qubits. In terms of numerical simulations, we show how the introduced variational algorithm depends on the choice of the aforementioned threshold depth and discuss its vulnerability to noise in terms of quantum gate errors.