Confined vacuum resonances as artificial atoms with tunable lifetime

TL;DR

This paper introduces a novel platform for creating tunable artificial atoms using vacuum-localized resonances confined in atomically engineered potential wells, enabling control over electron lifetimes and quantum states for quantum simulation and device applications.

Contribution

It demonstrates the construction and manipulation of atomically precise potential wells that host tunable quantum states and electron lifetimes, advancing the development of atomic-scale quantum devices.

Findings

Electron lifetimes can be extended and tuned via atomic assembly and tip-sample distance.

Controlled state-filling influences quantum many-body state evolution.

Negative differential resistance observed, enabling atomic-scale resonant tunnelling diodes.

Abstract

Atomically engineered artificial lattices are a useful tool for simulating complex quantum phenomena, but have so far been limited to the study of Hamiltonians where electron-electron interactions do not play a role -- but it's precisely the regime in which these interactions do matter where computational times lend simulations a critical advantage over numerical methods. Here, we propose a new platform for constructing artificial matter that relies on the confinement of field-emission resonances, a class of vacuum-localized discretized electronic states. We use atom manipulation of surface vacancies in a chlorine-terminated Cu(100) surface to reveal square patches of the underlying metal, thereby creating atomically-precise potential wells that host particle-in-a-box modes. By adjusting the shape and size of the confining potential, we can access states with different quantum numbers, making these patches attractive candidates as quantum dots or artificial atoms. We demonstrate that the lifetime of electrons in these engineered states can be extended and tuned through modification of the confining potential, either via atomic assembly or by changing the tip-sample distance. We also demonstrate control over a finite range of state-filling, a parameter which plays a key role in the evolution of quantum many-body states. We model the transport through the localized state to disentangle and quantify the lifetime-limiting processes, illustrating the critical dependency of the electron lifetime on the properties of the underlying bulk band structure. The interplay with the bulk bands also gives rise to negative differential resistance, opening possible avenues for engineering custom atomic-scale resonant tunnelling diodes, which exhibit similar current-voltage characteristics.