Registration Number
0225U004615,
(0125U002250)
, R & D reports
Title
Enhancement of superconducting pairing with the quantum control
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Посилення надпровідного спарювання в моделі Фермі-Габбарда за допомогою квантового контролю
Head
Sotnikov Andrii H., Доктор фізико-математичних наук
Registration Date
15-12-2025
Organization
National Science Center "Kharkiv Institute of Physics and Technology"
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The aim of the work is to study the characteristics of superconducting correlations in a one-dimensional half-filled Fermi-Hubbard chain with periodic boundary conditions under the action of an external driving field. For a better understanding of the superconducting and magnetic characteristics of the states of a system with a certain energy, the corresponding distribution diagrams will be constructed. The dynamics of superconducting correlations will be considered using the example of a system with a finite number of sites. The dependencies of the correlation amplitude on the choice of frequency and amplitude of the external field will be analyzed. To effectively transfer the system to an excited state with a non-zero value of the order parameter, it is planned to use quantum Lyapunov control. Its basis is the construction of the external field momentum in such a way that the derivative of the superconducting pairing parameter is maintained non-negative throughout the entire evolution. Using this method, it is assumed that it will be possible to construct a field that begins with a pulse with almost any ratio of amplitude and frequency, but brings the system to a state with the maximum value of the superconducting pairing parameter allowed by the selection rules. This, in particular, makes it possible to avoid the procedure of selecting optimal parameters for the excitation of stable superconductivity and to construct the desired pulse on the basis of an arbitrary strongly nonlinear signal. Lyapunov control will also be used when solving the problem of suppressing superconducting correlations in an already excited system. Using the example of this process, it is planned to show the nonlocality of control and investigate the possibility of using the system current to select the moment in time at which the introduction of a pulse will lead to the most effective suppression of superconductivity.
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The work is devoted to the study of the characteristics of superconducting correlations in a one-dimensional half-filled Fermi-Hubbard chain with periodic boundary conditions under the action of an external exciting field. For a better understanding of the superconducting and magnetic characteristics of the states of a system with a certain energy, the corresponding distribution diagrams are constructed. The dynamics of superconducting correlations is considered on the example of a system with a finite number of nodes. The dependencies of the correlation amplitude on the choice of frequency and amplitude of the external field are analyzed.
To effectively transfer the system to an excited state with a non-zero value, quantum Lyapunov control is employed. Its basis is the construction of the external field in such a way that the derivative of the superconducting pairing parameter is maintained non-negative throughout the entire evolution. Using this method, it is shown that it is possible to construct a field that starts with a pulse with almost any ratio of amplitude and frequency, but brings the system to a state with the maximum value of the superconducting pairing parameter allowed by the selection rules. This, in particular, made it possible to avoid the procedure of selecting optimal parameters for the excitation of stable superconductivity and to construct the desired pulse based on an arbitrary strongly nonlinear signal.
Lyapunov control is used when solving the problem of suppressing superconducting correlations in an already excited system. The example of this process shows the nonlocality of control and explores the possibility of using the system response to select the optimal time point at which the pulse application leads to the most effective suppression of superconductivity.
Product Description
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Andrii G. Sotnikov
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2025-12-15
