Intrinsic decoherence and recurrences in a large ferromagnetic $F = 1$ spinor Bose-Einstein condensate

TL;DR

This paper investigates how intrinsic decoherence and recurrences occur in the dynamics of a large F=1 spinor Bose-Einstein condensate under magnetic fields, revealing the effects of interactions and symmetry breaking.

Contribution

It provides analytical expressions for decoherence and recurrence times in large condensates, highlighting the impact of spin-spin interactions and magnetic fields.

Findings

Decoherence and recurrences depend on interaction strength and atom number.

Analytical formulas accurately predict decoherence and recurrence times.

Stationary states exhibit distinct features in weak and strong interaction regimes.

Abstract

Decoherence with recurrences appear in the dynamics of the one-body density matrix of an $F = 1$ spinor Bose-Einstein condensate, initially prepared in coherent states, in the presence of an external uniform magnetic field and within the single mode approximation. The phenomenon emerges as a many-body effect of the interplay of the quadratic Zeeman effect, that breaks the rotational symmetry, and the spin-spin interactions. By performing full quantum diagonalizations very accurate time evolution of large condensates are analyzed, leading to heuristic analytic expressions for the time dependence of the one-body density matrix, in the weak and strong interacting regimes, for initial coherent states. We are able to find accurate analytical expressions for both the decoherence and the recurrence times, in terms of the number of atoms and strength parameters, that show remarkable differences depending on the strength of the spin-spin interactions. The features of the stationary states in both regimes is also investigated. We discuss the nature of these limits in the light of the thermodynamic limit.