Berry phases of higher spins due to internal geometry of Majorana constellation and relation to quantum entanglement

TL;DR

This paper explores how the geometric structure of Majorana stars influences the Berry phase in higher spins, revealing a connection to quantum entanglement and internal constellation dynamics.

Contribution

It introduces a new geometric interpretation of Berry phases for spin-1 states, linking constellation twist to quantum entanglement in two-qubit systems.

Findings

Berry phase for spin-1 includes a twist-related term

The constellation's self-rotation correlates with entanglement

Majorana geometry reveals deep quantum state structures

Abstract

Majorana stars, the antipodal directions associated with the coherent states that are orthogonal to a spin state, provide a visualization and a geometric understanding of the structures of general quantum states. For example, the Berry phase of a spin-1/2 is given by half the solid angle enclosed by the close path of its Majorana star. It is conceivable that the Berry phase of higher spins may also be related to the geometry of the Majorana constellation. We find that for a spin-1 state, besides the expected contributions from the solid angles enclosed by the close paths of the two Majorana stars, the Berry phase includes a term related to the twist of the relative position vector around the barycenter vector of the two Majorana stars, i.e., the self-rotation of the constellation. Interestingly, if the spin-1 state is taken as a symmetrized two-qubit state, the extra contribution to the Berry phase is given by the self-rotation of the Majorana constellation weighted by the quantum entanglement of the two qubits. This discovery alludes to the relevance of the Majorana stellar geometry in representing the deep structures of quantum states and of quantum entanglement.