# Gate tuning from exciton superfluid to quantum anomalous Hall in van der Waals heterobilayer

## TL;DR

This paper demonstrates how van der Waals heterobilayers of 2D valley semiconductors can be electrically tuned to exhibit exciton superfluid, quantum anomalous Hall, and quantum spin Hall phases, enabling versatile quantum phase control.

## Contribution

It introduces a method to switch between different quantum phases in 2D heterobilayers using interlayer bias, revealing a new platform for quantum phase engineering.

## Key findings

- Tuning between exciton superfluid, QAH, and QSH phases via bias.
- Competition of Coulomb interaction and interlayer tunneling drives phase transitions.
- Potential for electrically controlling topological and superfluid states.

## Abstract

Van der Waals heterostructures of 2D materials provide a powerful approach towards engineering various quantum phases of matters. Examples include topological matters such as quantum spin Hall (QSH) insulator, and correlated matters such as exciton superfluid. It can be of great interest to realize these vastly different quantum matters on a common platform, however, their distinct origins tend to restrict them to material systems of incompatible characters. Here we show that heterobilayers of two-dimensional valley semiconductors can be tuned through interlayer bias between an exciton superfluid (ES), a quantum anomalous Hall (QAH) insulator, and a QSH insulator. The tunability between these distinct phases results from the competition of Coulomb interaction with the interlayer quantum tunnelling that has a chiral form in valley semiconductors. Our findings point to exciting opportunities for harnessing both protected topological edge channels and bulk superfluidity in an electrically configurable platform.