Coherence Effects in Multi-Level Systems

Laurentius Windholz

Coherent population trapping (CPT) is treated in multi–level systems, excited by two– or four–frequency laser light. The dynamics of filling non–absorbing (dark) states is investigated. In cases where all transitions involved are excited (closed systems), the effect becomes dependent on the relative phase of the light waves. Further electromagnetically induced transparency (EIT) is described in three– and four–level systems and used for effective side band generation.

Luis Roa, A. Krügel

M. M. Al'perin, Ya. D. Klubis

Nahid Binandeh Dehaghani, A. Pedro Aguiar, Rafał Wiśniewski

This paper addresses the optimal control of quantum coherence in multi-level systems, modeled by the Lindblad master equation, which captures both unitary evolution and environmental dissipation. We develop an energy minimization framework to control the evolution of a qutrit (three-level) quantum system while preserving coherence between states. The control problem is formulated using Pontryagin's Minimum Principle in the form of Gamkrelidze, incorporating state constraints to ensure coherence remains within desired bounds. Our approach accounts for Markovian decoherence, demonstrating that the Lindblad operator is non-unital, which reflects the irreversible decay processes inherent in the system. The results provide insights into effectively maintaining quantum coherence in the presence of dissipation.

Nahid Binandeh Dehaghani, A. Pedro Aguiar, Rafał Wiśniewski

This paper addresses the optimal control of quantum coherence in multi-level systems, modeled by the Lindblad master equation, which captures both unitary evolution and environmental dissipation. We develop an energy minimization framework to control the evolution of a qutrit (three-level) quantum system while preserving coherence between states. The control problem is formulated using Pontryagin’s Minimum Principle in the form of Gamkrelidze, incorporating state constraints to ensure coherence remains within desired bounds. Our approach accounts for Markovian decoherence, demonstrating that the Lindblad operator is non-unital, which reflects the irreversible decay processes inherent in the system. The results provide insights into effectively maintaining quantum coherence in the presence of dissipation.

Jiří Blažek