Optimizing Variational Quantum Algorithms with qBang: Efficiently Interweaving Metric and Momentum to Navigate Flat Energy Landscapes
Artikel i vetenskaplig tidskrift, 2024

Variational quantum algorithms (VQAs) represent a promising approach to utilizing current quantum computing infrastructures. VQAs are based on a parameterized quantum circuit optimized in a closed loop via a classical algorithm. This hybrid approach reduces the quantum processing unit load but comes at the cost of a classical optimization that can feature a flat energy landscape. Existing optimization techniques, including either imaginary time -propagation, natural gradient, or momentum -based approaches, are promising candidates but place either a significant burden on the quantum device or suffer frequently from slow convergence. In this work, we propose the quantum Broyden adaptive natural gradient (qBang) approach, a novel optimizer that aims to distill the best aspects of existing approaches. By employing the Broyden approach to approximate updates in the Fisher information matrix and combining it with a momentumbased algorithm, qBang reduces quantumresource requirements while performing better than more resource -demanding alternatives. Benchmarks for the barren plateau, quantum chemistry, and the maxcut problem demonstrate an overall stable performance with a clear improvement over existing techniques in the case of flat (but not exponentially flat) optimization landscapes. qBang introduces a new development strategy for gradient -based VQAs with a plethora of possible improvements.

Författare

David Fitzek

Chalmers, Mikroteknologi och nanovetenskap, Tillämpad kvantfysik

Volvo Group

Robert Jonsson

Chalmers, Mikroteknologi och nanovetenskap, Tillämpad kvantfysik

Saab

Werner Barucha-Dobrautz

Chalmers, Kemi och kemiteknik

Christian Schäfer

Chalmers, Mikroteknologi och nanovetenskap

Chalmers, Fysik

Quantum

2521327X (eISSN)

Vol. 8 1313

QC-SQUARED

Europeiska kommissionen (EU) (EC/HE/101062864), 2022-01-07 -- 2025-06-30.

Kvantplasmonik – en teknologi för foton-fotonväxelverkan på kvantnivå vid rumstemperatur

Vetenskapsrådet (VR) (2016-06059), 2017-01-01 -- 2022-12-31.

Ämneskategorier

Beräkningsmatematik

DOI

10.22331/q-2024-04-09-1313

Mer information

Senast uppdaterat

2024-06-18