Energy spectrum and quantum phase transition of the coupled single spin and an infinitely coordinated Ising chain

• Seidali Seidov,
• Natalia Pugach and
• Anatolie Sidorenko

Beilstein J. Nanotechnol. 2025, 16, 1668–1676, doi:10.3762/bjnano.16.117

• .16.117 Abstract In this work we consider a spin model composed of a single spin and connected to an infinitely coordinated Ising chain. Theoretical models of this type arise from various fields of theoretical physics, such as theory of open systems, quantum control, and quantum computations. In the

• we obtain the spectrum of the whole system and study the properties of the ground-state quantum phase transition. Keywords: Ising chain; Lipkin–Meshkov–Glick model; quantum phase transitions; Introduction In the present manuscript, we consider a single spin connected to an infinitely coordinated

• Ising chain. From a purely theoretical point of view, this model arises when studying the physics of open systems [1][2]. In this case, the chain is modelling the external environment to which the single spin is connected. In such models, it is convenient to study not only Markovian dynamics of the