Continuously tunable dipolar exciton geometry for controlling bosonic quantum phase transitions

TL;DR

This paper demonstrates a method to continuously tune the geometry and binding energy of dipolar excitons in a 2D heterostructure, enabling control over many-body quantum phase transitions and advancing programmable optoelectronic applications.

Contribution

It introduces a polarizable interlayer exciton with in situ tunable geometry and energy, controlled via an electric field, which was not possible in fixed solid-state systems.

Findings

In situ control of exciton dipole length and radius.

Transformation of Mott transition from gradual to abrupt.

Establishment of exciton geometry as a tunable parameter.

Abstract

The geometry and binding energy of excitons, set by electron-hole wavefunction distributions, are fundamental factors that underpin their many-body interactions and determine optoelectronic properties of semiconductors. However, in typical solid-state systems, these quantities are fixed by material composition and structure. Here we introduce a polarizable interlayer exciton hosted in a two-dimensional tetralayer heterostructure whose dipole length, in-plane radius, and binding energy can be continuously programmed in situ over a wide range, enabling direct control over the nature of excitonic many-body phase transitions. An out-of-plane electric field redistributes layer-hybridized electron-hole wavefunctions, realizing in situ control of exciton geometry through a strong quadratic Stark response. This tunability further regulates the nature of interaction-driven Mott transition, transforming it from gradual to abrupt. Our results establish exciton geometry as a continuously tunable materials parameter, opening routes to exciton-based quantum phase-transition simulators and guiding the design of emergent optoelectronic functionalities from programmable excitonic materials.