Confined Vacuum Resonances as Artificial Atoms with Tunable Lifetime

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. However, it is precisely the regime in which these interactions do matter where computational times lend simulations a critical advantage over numerical methods. Here, we propose a 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 dimensions 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 dependence of the electron lifetime on the properties of the underlying bulk band structure. The interplay with the bulk bands gives rise to negative differential resistance, leading to possible applications in engineering custom atomic-scale resonant tunnelling diodes, which exhibit similar current–voltage characteristics.

Engineering quantum states and electronic landscapes through surface molecular nanoarchitectures

“…Novel quantum properties are also envisioned upon the advancement of design principles of engineered 2DEGs. In particular, electronic scattering and confinement effects should be transferable to image potential states that are accessible via STS or 2PPE techniques (Echenique et al, 2004;Schouteden and Van Haesendonck, 2012;Niesner and Fauster, 2014;Rejali et al, 2022). Additionally, network modified 2DEGs have recently been proposed to play a key role in the stabilization and the significant energy down-shifting of superatom molecular orbitals (Kawai et al, 2021).…”

Formation of an Extended Quantum Dot Array Driven and Autoprotected by an Atom-Thick h-BN Layer

“…As IPSs previously served as model systems to study excited states, − probing confined IPSs by 2PPE and STS in such arrays could shed light on how confinement and QD coupling influences the lifetime of these states. Additionally, it was recently suggested by Rejali et al that arrays of confined IPSs in an STM setup might be employed to study electron–electron interactions. Thus, the system presented provides a promising platform for the study of such quantum phenomena.…”