Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

# Decoherence and Recurrences in a Large Ferromagnetic $F = 1$ Spinor Bose-Einstein Condensate

Version 1 : Received: 10 November 2020 / Approved: 12 November 2020 / Online: 12 November 2020 (14:40:51 CET)

How to cite: Romero-Rochin, V.; Sandoval-Santana, J.C.; Paredes, R. Decoherence and Recurrences in a Large Ferromagnetic $F = 1$ Spinor Bose-Einstein Condensate. Preprints 2020, 2020110353 (doi: 10.20944/preprints202011.0353.v1). Romero-Rochin, V.; Sandoval-Santana, J.C.; Paredes, R. Decoherence and Recurrences in a Large Ferromagnetic $F = 1$ Spinor Bose-Einstein Condensate. Preprints 2020, 2020110353 (doi: 10.20944/preprints202011.0353.v1).

## 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 density matrix, in the weak and strong interacting regimes. 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. We discuss the nature of these limits in the light of the thermodynamic limit.

## Keywords

Bose-Einstein condensates; quantum decoherence; full quantum dynamics

## Subject

PHYSICAL SCIENCES, Acoustics

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