Spin dynamics of strongly-interacting, two-dimensional ensembles of V_B^- defects in hexagonal Boron Nitride

Conventionally, strongly interacting color-center ensembles are three-dimensional in nature. While such systems have been used extensively as both quantum sensors and simulators of many-body dynamics, the ability to access lower dimensional physics using such solid-state color-centers remains an exciting prospect. Here, we investigate the many-body dynamics of ensembles of negatively-charged boron vacancy (V_B^-) defects in few-layer hBN flakes, where the flake thickness is smaller than the average inter-defect spacing. In this regime, we demonstrate that the emergent spin dynamics are governed by the native dipolar interactions between the V_B^- defects. In particular, we utilize a form of many-body noise spectroscopy where the dimensionality directly enters the temporal profile of the V_B^- defects’ decoherence dynamics. Building on this, we perform measurements of local spin-spin auto-correlation functions in order to explore and contrast spin transport in 2D thin flakes and 3D bulk ensembles.