Quantum dynamics of spin-J particles in static and rotating magnetic fields: Entanglement resonances and kinks

TL;DR

This paper investigates the quantum dynamics and entanglement resonances of spin-J particles in magnetic fields, revealing periodic state transitions and potential for entanglement control, with implications for quantum technologies.

Contribution

It introduces new resonance conditions and analyzes entanglement dynamics, including kinks, in spin-J systems with dipolar interactions, expanding understanding of quantum control mechanisms.

Findings

Resonant, periodic oscillations between maximally stretched states occur regardless of J.

Resonances and kinks in entanglement dynamics are identified and can be engineered.

Weak dipolar interactions are relevant for dipolar Bose-Einstein condensates.

Abstract

We examine the quantum dynamics of both a single spin-J particle and a pair of spin-J particles in the presence of static and rotating magnetic fields, which can be important for qudit-based quantum technologies. Notably, we find resonant, periodic oscillations between two maximally stretched states, irrespective of the value of J. Additionally, we observe periodic transitions between sublevels with magnetic quantum numbers of opposite signs. The dynamics also exhibit a periodic transfer of the spin to the maximally stretched state, starting from the ground state of the initial Hamiltonian. For a pair of spins, we derive various resonance conditions and further analyze the entanglement generated by dipole-dipole interactions. In the case of two spin-1/2 particles, the entanglement dynamics reveal resonances and kinks in the maximum entanglement, and their criteria can be obtained from the energy spectrum. Strikingly, we show that the kink can be exploited to engineer the entanglement dynamics. Finally, we briefly discuss the regime of weak dipolar interactions, which are relevant for dipolar Bose-Einstein condensates.