文摘
This paper gives a new algebraic interpretation for the algebra generated by the quantum cluster variables of the \(A_r\) quantum Q-system (Di Francesco and Kedem in Int Math Res Not IMRN 10:2593–2642, 2014). We show that the algebra can be described as a quotient of the localization of the quantum algebra \(U_{\sqrt{q}}({\mathfrak {n}}[u,u^{-1}])\subset U_{\sqrt{q}}(\widehat{{\mathfrak {sl}}}_2)\), in the Drinfeld presentation. The generating current is made up of a subset of the cluster variables which satisfy the Q-system, which we call fundamental. The other cluster variables are given by a quantum determinant-type formula, and are polynomials in the fundamental generators. The conserved quantities of the discrete evolution (Di Francesco and Kedem in Adv Math 228(1):97–152, 2011) described by quantum Q-system generate the Cartan currents at level 0, in a non-standard polarization. The rest of the quantum affine algebra is also described in terms of cluster variables.