Nonunitary Preparation of Nontrivial States from Trivial Regimes in Two-Dimensional Topological Insulators

TL;DR

This paper introduces a nonunitary, noise-assisted method for preparing nontrivial topological states in 2D topological insulators, overcoming limitations of traditional adiabatic protocols.

Contribution

It proposes a novel nonunitary protocol using dephasing noise to reliably generate topological states from trivial regimes.

Findings

Dephasing noise enables topological state preparation without crossing gap-closing points.

The resulting states' topological invariants match those of the target Hamiltonian.

The method offers an alternative to adiabatic protocols for topological state engineering.

Abstract

While remarkable progress has been achieved in engineering nontrivial Hamiltonians across a wide range of physical platforms, preparing their corresponding nontrivial ground states remains a major experimental challenge. The commonly used strategy for state preparation relies on adiabatic protocols. However, when a trivial initial state is unitarily driven toward nontrivial regimes, the dynamics must cross gap-closing critical points, rendering the process intrinsically nonadiabatic, and the state remains topologically trivial. Here, we present a nonunitary method for dynamically preparing nontrivial states in two-dimensional topological insulators. By introducing dephasing noise into a slowly driven unitary evolution, we demonstrate that the topological number of the resulting dephased states can coincide with that of the target nontrivial Hamiltonian. This nearly adiabatic nonunitary state-preparation protocol provides a powerful alternative to conventional adiabatic approaches for accessing topological states.