Optimal Paths for Symmetric Actions in the Unitary Group

Given a positive and unitarily invariant Lagrangian L defined in the algebra of matrices, and a fixed time interval [0, t0 ] ⊂ ℝ, we study the action defined in the Lie group of n × n unitary matrices U(n) by, where α: [0, t0] → U(n) is a rectifiable curve. We prove that the one-parameter subgroups...

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Detalles Bibliográficos
Autores: Antezana, Jorge Abel, Larotonda, Gabriel Andrés, Varela, Alejandro
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2014
País:Argentina
Institución:Consejo Nacional de Investigaciones Científicas y Técnicas
Repositorio:CONICET Digital (CONICET)
Idioma:inglés
OAI Identifier:oai:ri.conicet.gov.ar:11336/37335
Acceso en línea:http://hdl.handle.net/11336/37335
Access Level:acceso abierto
Palabra clave:Geodesic Segment
Lagrangian
Optimal Path
Unitarily Invariant Norm
Unitary Group
Grassmann Manifold
Angular Metric
https://purl.org/becyt/ford/1.1
https://purl.org/becyt/ford/1
Descripción
Sumario:Given a positive and unitarily invariant Lagrangian L defined in the algebra of matrices, and a fixed time interval [0, t0 ] ⊂ ℝ, we study the action defined in the Lie group of n × n unitary matrices U(n) by, where α: [0, t0] → U(n) is a rectifiable curve. We prove that the one-parameter subgroups of U(n) are the optimal paths, provided the spectrum of the exponent is bounded by π. Moreover, if L is strictly convex, we prove that one-parameter subgroups are the unique optimal curves joining given endpoints. Finally, we also study the connection of these results with unitarily invariant metrics in U(n) as well as angular metrics in the Grassmann manifold.