We propose a novel approach to probe primordial inhomogeneity in hot and
dense matter which could be realized in non-central heavy-ion collisions.
Although the Hanbury Brown and Twiss (HBT) interferometry is commonly used to
infer the system size, the cluster size should be detected if substructures
emerge in space. We demonstrate that a signal peak in the HBT two-particle
correlation stands at the relative momentum corresponding to the spatial scale
of pseudo one-dimensional modulation. We assess detectability using the data
prepared by an event generator (AMPT model) with clustering implemented in the
particle distribution.Comment: 5 pages, 4 figure