We study the artificial molecular states formed in laterally coupled double semiconductor nanorings by systems containing one, two and three electrons. An interplay of the interring tunneling and the electron-electron interaction is described and its consequences for the magnetization and charging properties of the system are determined. It is shown that both the magnetic dipole moment generated by the double ring structure and the chemical potential of the system as function of the external magnetic field strongly depend on the number of electrons and the interring barrier thickness. Both the magnetization and chemical potentials exhibit cusps at the magnetic fields inducing ground-state parity and / or spin transformations. The symmetry transformations are discussed for various tunnel coupling strengths: from rings coupled only electrostatically to the limit of coalesced rings. We find that in the ground-states for rings of different radii the magnetic field transfers the electron charge from one ring to the other. The calculations are performed with the configuration interaction method based on an approach of Gaussian functions centered on a rectangular array of points covering the studied structure. Electron-electron correlation is also discussed.
From laterally modulated two-dimensional electron gas towards artificial graphene
在GaAs/Al $_x$ Ga $_{1-x}$ As异质结构中用刻蚀的六方超晶格测量了回旋共振的远红外透射。观察到共振位置对磁场的非线性依赖性以及其分裂成几种模式。我们的解释，微扰计算的基础上，描述了所观察到的现象作为一个弱的影响的横向潜力的二维电子气。使用这种方法，我们发现了横向图案化的参数之间的相关性和所产生的有效电位，从而获得有关如何调整的电子能带结构的见解。使用简化模型计算了迷你带色散，并使我们能够制定四个基本标准，这些标准必须满足才能在此类系统中达到石墨烯类物理学。
Highly uniform and ordered nanodot arrays are crucial for high performance quantum optoelectronics including new semiconductor lasers and single photon emitters, and for synthesizing artificial lattices of interacting quasiparticles towards quantum information processing and simulation of many-body physics. Van der Waals heterostructures of 2D semiconductors are naturally endowed with an ordered nanoscale landscape, i.e. the moiré pattern that laterally modulates electronic and topographic structures. Here we find these moiré effects realize superstructures of nanodot confinements for long-liv…
Scanning tunneling microscopy is a powerful tool to build artificial atomic structures even not exist in nature but possess exotic properties. We here constructed Lieb lattices with different lattice constants by real atoms, i.e., Fe atoms on Ag(111) and probed their electronic properties. We find a surprising long-range effective electron wavefunction overlap between Fe adatoms as it exhibits a 1/r2-dependence with the interatomic distance r instead of the theoretically predicted exponential one. Combining control experiments, tight-binding and Green's function calculations, we attribute the …
Quantum confinement has made it possible to detect and manipulate single-electron charge and spin states. The recent focus on two-dimensional (2D) materials has attracted significant interests on possible applications to quantum devices, including detecting and manipulating either single-electron charging behavior or spin and valley degrees of freedom. However, the most popular model systems, consisting of tunable double-quantum-dot molecules, are still extremely difficult to realize in these materials. We show that an artificial molecule can be reversibly formed in atomically thin MoS2 sandwi…
The magnetic skyrmion structure can be formed in the chiral magnets (CMs) with strong Dzyaloshinskii-Moriya interactions. In this work, we propose a way of artificially tailoring the topological details of the skyrmion such as its radial and whirling symmetric patterns by external magnetic fields besieging the CM slab. As long as the boundary magnetic fields are strong enough to fix the boundary ferromagnetism, the attained skyrmion profile is stable over time. The dynamics of spins is considered by numerically solving the non-equilibrium Landau-Lifshitz-Gilbert equation.
Understanding strongly interacting electrons enables the design of materials, nanostructures and devices. Developing this understanding relies on the ability to tune and control electron-electron interactions by, e.g., confining electrons to atomically thin layers of 2D crystals with reduced screening. The interplay of strong interactions on a hexagonal lattice with two nonequivalent valleys, topological moments, and the Ising-like spin-orbit interaction gives rise to a variety of phases of matter corresponding to valley and spin polarized broken symmetry states. In this work we describe a hig…
Given its unrivaled potential of integration and scalability, silicon is likely to become a key platform for large-scale quantum technologies. Individual electron-encoded artificial atoms either formed by impurities or quantum dots have emerged as a promising solution for silicon-based integrated quantum circuits. However, single qubits featuring an optical interface needed for large-distance exchange of information have not yet been isolated in such a prevailing semiconductor. Here we show the isolation of single optically-active point defects in a commercial silicon-on-insulator wafer implan…
Controlling the size and shape of nanopores in two-dimensional materials is a key challenge in applications such as DNA sequencing, sieving, and quantum emission in artificial atoms. We here investigate experimentally and theoretically triangular vacancies in (unconventional) Bernal-stacked AB-h-BN formed using a high-energy electron beam. Due to the geometric configuration of AB-h-BN, triangular pores in different layers are aligned, and their sizes are controlled by the duration of the electron irradiation. Interlayer covalent bonding at the vacancy edge is not favored, as opposed to what oc…
The small size and excellent integrability of silicon metal-oxide-semiconductor (SiMOS) quantum dot spin qubits make them an attractive system for mass-manufacturable, scaled-up quantum processors. Furthermore, classical control electronics can be integrated on-chip, in-between the qubits, if an architecture with sparse arrays of qubits is chosen. In such an architecture qubits are either transported across the chip via shuttling, or coupled via mediating quantum systems over short-to-intermediate distances. This paper investigates the charge and spin characteristics of an elongated quantum do…
