Optimization of Time-Dependent Decoherence Rates and Coherent Control for a Qutrit System

Fuente: arXiv
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Autores principales: Morzhin, Oleg, Pechen, Alexander
Formato: Preprint
Publicado: 2023
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author Morzhin, Oleg
Pechen, Alexander
author_facet Morzhin, Oleg
Pechen, Alexander
contents The work considers an open qutrit system whose density matrix $ρ(t)$ evolution is governed by the Gorini-Kossakowski-Sudarshan-Lindblad master equation with simultaneous coherent (in the Hamiltonian) and incoherent (in the superoperator of dissipation) controls. Incoherent control makes the decoherence rates depending on time in a specific controlled manner and within clear physical mechanics. We consider the problem of maximizing the Hilbert-Schmidt overlap between the system's final state $ρ(T)$ and a given target state $ρ_{\rm target}$ and the problem of minimizing the squared Hilbert-Schmidt distance between these states. For the both problems, we perform their realifications, derive the corresponding Pontryagin function, adjount system (with the two cases of transversality conditions in view of the two terminal objectives), and gradients of the objectives, adapt the one-, two-, three-step gradient projection methods. For the problem of maximizing the overlap, we also adapt the regularized first-order Krotov method. In the numerical experiments, we analyze, first, the methods' operation and, second, the obtained control processes, in respect to considering the environment as a resource via incoherent control.
format Preprint
id arxiv_https___arxiv_org_abs_2308_03976
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Optimization of Time-Dependent Decoherence Rates and Coherent Control for a Qutrit System
Morzhin, Oleg
Pechen, Alexander
Quantum Physics
The work considers an open qutrit system whose density matrix $ρ(t)$ evolution is governed by the Gorini-Kossakowski-Sudarshan-Lindblad master equation with simultaneous coherent (in the Hamiltonian) and incoherent (in the superoperator of dissipation) controls. Incoherent control makes the decoherence rates depending on time in a specific controlled manner and within clear physical mechanics. We consider the problem of maximizing the Hilbert-Schmidt overlap between the system's final state $ρ(T)$ and a given target state $ρ_{\rm target}$ and the problem of minimizing the squared Hilbert-Schmidt distance between these states. For the both problems, we perform their realifications, derive the corresponding Pontryagin function, adjount system (with the two cases of transversality conditions in view of the two terminal objectives), and gradients of the objectives, adapt the one-, two-, three-step gradient projection methods. For the problem of maximizing the overlap, we also adapt the regularized first-order Krotov method. In the numerical experiments, we analyze, first, the methods' operation and, second, the obtained control processes, in respect to considering the environment as a resource via incoherent control.
title Optimization of Time-Dependent Decoherence Rates and Coherent Control for a Qutrit System
topic Quantum Physics
url https://arxiv.org/abs/2308.03976