Balanced metrics for K\"ahler-Ricci solitons and quantized Futaki invariants

Abstract

We show that a K\"ahler-Ricci soliton on a Fano manifold can always be smoothly approximated by a sequence of relative anticanonically balanced metrics, also called quantized K\"ahler-Ricci solitons. The proof uses a semiclassical estimate on the spectral gap of an equivariant Berezin transform to extend a strategy due to Donaldson, and can be seen as the quantization of a method due to Tian and Zhu, using quantized Futaki invariants as obstructions for quantized K\"ahler-Ricci solitons. As corollaries, we recover the uniqueness of K\"ahler-Ricci solitons up to automorphisms, and show how our result also applies to K\"ahler-Einstein Fano manifolds with general automorphism group.