Monte Carlo approach for finding optimally controlled quantum gates with differential geometry

Fuente: arXiv
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Main Authors: da Silva, Adonai Hilário, Castelano, Leonardo Kleber, Napolitano, Reginaldo de Jesus
Format: Preprint
Published: 2025
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author da Silva, Adonai Hilário
Castelano, Leonardo Kleber
Napolitano, Reginaldo de Jesus
author_facet da Silva, Adonai Hilário
Castelano, Leonardo Kleber
Napolitano, Reginaldo de Jesus
contents A unitary evolution in time may be treated as a curve in the manifold of the special unitary group. The length of such a curve can be related to the energetic cost of the associated computation, meaning a geodesic curve identifies an energetically optimal path. In this work, we employ sub-Riemannian geometry on the manifold of the unitary group to obtain optimally designed Hamiltonians for generating single-qubit gates in an environment with the presence of dephasing noise as well as a two-qubit gate under a time-constant crosstalk interaction. The resulting geodesic equation involves knowing the initial conditions of the parameters that cannot be obtained analytically. We then introduce a random sampling method combined with a minimization function and a cost function to find initial conditions that lead to optimal control fields. We also compare the optimized control fields obtained from the solutions of the geodesic equation with those extracted from the well-known Krotov method. Both approaches provide high fidelity values for the desired quantum gate implementation, but the geodesic method has the advantage of minimizing the required energy to execute the same task. These findings bring new insights for the design of more efficient fields in the arsenal of optimal control theory.
format Preprint
id arxiv_https___arxiv_org_abs_2503_09593
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Monte Carlo approach for finding optimally controlled quantum gates with differential geometry
da Silva, Adonai Hilário
Castelano, Leonardo Kleber
Napolitano, Reginaldo de Jesus
Quantum Physics
Computational Physics
A unitary evolution in time may be treated as a curve in the manifold of the special unitary group. The length of such a curve can be related to the energetic cost of the associated computation, meaning a geodesic curve identifies an energetically optimal path. In this work, we employ sub-Riemannian geometry on the manifold of the unitary group to obtain optimally designed Hamiltonians for generating single-qubit gates in an environment with the presence of dephasing noise as well as a two-qubit gate under a time-constant crosstalk interaction. The resulting geodesic equation involves knowing the initial conditions of the parameters that cannot be obtained analytically. We then introduce a random sampling method combined with a minimization function and a cost function to find initial conditions that lead to optimal control fields. We also compare the optimized control fields obtained from the solutions of the geodesic equation with those extracted from the well-known Krotov method. Both approaches provide high fidelity values for the desired quantum gate implementation, but the geodesic method has the advantage of minimizing the required energy to execute the same task. These findings bring new insights for the design of more efficient fields in the arsenal of optimal control theory.
title Monte Carlo approach for finding optimally controlled quantum gates with differential geometry
topic Quantum Physics
Computational Physics
url https://arxiv.org/abs/2503.09593