Optimizing quantum circuits with Riemannian gradient flow

Feb 14, 2022
15 pages
Published in:
  • Phys.Rev.A 107 (2023) 6, 062421
  • Published: Jun 27, 2023
e-Print:
DOI:

Citations per year

2018202020222024202502468101214
Abstract: (APS)
Variational quantum algorithms are a promising class of algorithms that can be performed on currently available quantum computers. In most settings, the free parameters of a variational circuit are optimized using a classical optimizer that updates parameters in Euclidean geometry. Since quantum circuits are elements of the special unitary group, we can consider an alternative optimization perspective that depends on the structure of this group. In this work, we investigate a Riemannian optimization scheme over the special unitary group and we discuss its implementation on a quantum computer. We illustrate that the resulting Riemannian gradient-flow algorithm has favorable optimization properties for deep circuits and that an approximate version of this algorithm can be performed on near-term hardware. We highlight the connections of our work with previously proposed heuristics like ADAPT-VQE and show that they can be understood as variants of our algorithm.
  • geometry: Euclidean
  • unitarity
  • hardware
  • flow
  • structure
  • quantum circuit
  • optimization
  • quantum algorithm: variational