Stability Diagram of a Few-Electron Triple Dot

Abstract

Individual and coupled quantum dots containing one or two electrons have been realized and are regarded as components for future quantum information circuits. In this Letter we map out experimentally the stability diagram of the few-electron triple dot system, the electron configuration map as a function of the external tuning parameters, and reveal experimentally for the first time the existence of quadruple points, a signature of the three dots being in resonance. In the vicinity of these quadruple points we observe a duplication of charge transfer transitions related to charge and spin reconfigurations triggered by changes in the total electron occupation number. The experimental results are largely reproduced by equivalent circuit analysis and Hubbard models. Our results are relevant for future quantum mechanical engineering applications within both quantum information and quantum cellular automata architectures.

Quantum simulation of a Fermi–Hubbard model using a semiconductor quantum dot array

“…Seminal efforts are underway in the control of artificial quantum systems, that can be made to emulate the underlying Fermi-Hubbard models [5, 6, 7, 8,9,10,11]. Electrostatically confined conduction band electrons define interacting quantum coherent spin and charge degrees of freedom that allow all-electrical pure-state initialisation and readily adhere to an engineerable Fermi-Hubbard Hamiltonian [12,13,14,15,16,17,18,19,20,21,22,23]. Until now, however, the substantial electrostatic disorder inherent to solid state has made attempts at emulating Fermi-Hubbard physics on solid-state platforms few and far between [24,25].…”

“…Furthermore, scaling to similarly homogeneous but larger system sizes is not always straightforward [5,7,8,9,10,11,25]. Semiconductor quantum dots form a scalable platform that is naturally described by a Fermi-Hubbard model in the low-temperature, strong-interaction regime, when cooled down to dilution temperatures [12,13,15,14,16]. As such, pure state initialization of highly-entangled states is possible even without the use of adiabatic initialization schemes [27].…”

Characterizing gate operations near the sweet spot of an exchange-only qubit

“…In a more elaborate model, we could expand this to include the following terms U 0 j=1,2,3 n j↑ n j ↓ + U 1 j=1,2 n j n j+1 + U 2 n 1 n 3 , (A12) corresponding to double-occupations, nearest-neighbor couplings, and next-nearest-neighbor couplings. Such models have previously been explored by some authors, 6,14,34 while other authors consider a basis set of singly-occupied states, 5 where all the Coulomb terms are incorporated into the exchange interaction parameters of an effective Hamiltonian.…”

“…3 Several logical spin qubits have been proposed for quantum dot architectures. 4 Here, we consider the exchange-only logical qubit, 5 formed of three electrons in a triple dot, [6][7][8] as illustrated in Fig. 1(d).…”

Antisymmetric Spin–Orbit Coupling Effect on Kondo-Induced Electric Polarization in a Triangular Triple Quantum Dot

“…For the last decade, the TTQD has been experimentally realized in AlGaAs/GaAs heterostructures [33][34][35][36][37] and self-assembled InAs systems. 38) The recent development of a fabrication technique has stimulated theoretical investigations of various TTQD Kondo systems because of the high potentiality for versatile quantum devices.…”