Realizing Quantum Materials with Helium: Helium films at ultralow temperatures, from strongly correlated atomically layered films to topological superfluidity

TL;DR

This paper reviews recent experimental advances in using helium films at ultralow temperatures to create and study various quantum materials, revealing new quantum states and phenomena relevant to condensed matter physics.

Contribution

It provides a comprehensive overview of how helium films serve as quantum simulators for exploring emergent quantum states and topological superfluidity.

Findings

Realization of 2D Fermi systems with Mott-Hubbard transition

Observation of topological mesoscopic superfluidity

Identification of 2D quantum spin liquids

Abstract

This article provides an overview, primarily from an experimental perspective, of recent progress and future prospects in using helium to realize a range of quantum materials of generic interest, by "top-down" and "bottom-up" nanotechnology. We can grow model systems to realise new quantum states of matter, and explore key issues in condensed matter physics. In the language of cold atomic gases, two dimensional and confined 3He and 4He provide "quantum simulators", with the potential to uncover new emergent quantum states. These include: strictly 2D Fermi system with Mott-Hubbard transition; interacting coupled 2D fermion-boson system; heavy fermion quantum criticality; ideal 2D frustrated ferromagnetism; 2D quantum spin liquid; intertwined superfluid and density wave order with emergent large symmetry; topological mesoscopic superfluidity (new materials and emergent excitations).