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Scaling up qubits is a necessary step to realize useful systems of quantum computation. Here we demonstrate coherent manipulations of four individual electron spins using a micro-magnet method in a quadruple quantum dot - the largest number…

We propose a new implementation of a universal set of one- and two-qubit gates for quantum computation using the spin states of coupled single-electron quantum dots. Desired operations are effected by the gating of the tunneling barrier…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 Daniel Loss , David P. DiVincenzo

Based on electron spins in semiconductor quantum dots as qubits, a new quantum controlled-NOT(CNOT) gate is constructed in solid nanostructure without resorting to spin-spin interactions. Single electron tunneling technology and coherent…

Quantum Physics · Physics 2009-11-13 Yin-Zhong Wu , Wei-Min Zhang

We investigate the stability of few-electron quantum phases in vertically coupled quantum dots under a magnetic field of arbitrary strength and direction. The orbital and spin stability diagrams of realistic devices containing up to five…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Devis Bellucci , Massimo Rontani , Guido Goldoni , Elisa Molinari

We study controllable exchange coupling between two singlet-triplet qubits. We start from the original second quantized Hamiltonian of a quadruple quantum dot system and obtain the effective spin-spin interaction between the two qubits…

Mesoscale and Nanoscale Physics · Physics 2013-05-13 Rui Li , Xuedong Hu , J. Q. You

We have studied the dissipative dynamics of a solid-state qubit with an extra electron confined to either one of two coupled quantum dots. Previous theoretical work based on Bloch-type rate equations gave an unphysical uniform occupation…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Shi-Hua Ouyang , Chi-Hang Lam , J. Q. You

Tunnel-coupled pairs of optically active quantum dots - quantum dot molecules (QDMs) - offer the possibility to combine excellent optical properties such as strong light-matter coupling with two-spin singlet-triplet ($S-T_0$) qubits having…

We analyzed theoretically localized charge relaxation in a double quantum dot (QD) system coupled with continuous spectrum states in the presence of localized electrons Coulomb interaction in a single QD. We have found that for a wide range…

Mesoscale and Nanoscale Physics · Physics 2012-07-13 V. N. Mantsevich , N. S. Maslova , P. I. Arseyev

The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the resonant exchange (RX) qubit and the exchange-only qubit, but we also…

Mesoscale and Nanoscale Physics · Physics 2017-09-14 Maximilian Russ , Guido Burkard

Singlet-triplet spin blockade in a few-electron lateral double quantum dot is investigated using simultaneous transport and charge-sensing measurements. Transport from the (1,1) to the (0,2) electron occupancy states is strongly suppressed…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 A. C. Johnson , J. R. Petta , C. M. Marcus , M. P. Hanson , A. C. Gossard

Using electrostatic gates to control the electron positions, we present a new controlled-NOT gate based on quantum dots. The qubit states are chosen to be the spin states of an excess conductor electron in the quantum dot; and the main…

Quantum Physics · Physics 2007-05-23 Cyrus C. Y. Lin , Chopin Soo , Yin-Zhong Wu , Wei-Min Zhang

In this work, we propose a stable charging scheme mediated by a three-level system (qutrit), which renders a unidirectional energy flow from an external power source to an $(N+1)$-dimensional quantum battery. By virtue of the qutrit…

Quantum Physics · Physics 2025-09-09 Chen-yi Zhang , Jun Jing

We report the experimental realization of double quantum dots in single-walled carbon nanotubes. The device consists of a nanotube with source and drain contact, and three additional top-gate electrodes in between. We show that, by…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 M. R. Graeber , M. Weiss , C. Schoenenberger

A quantum dot hybrid qubit formed from three electrons in a double quantum dot has the potential for great speed, due to presence of level crossings where the qubit becomes charge-like. Here, we show how to take full advantage of the level…

Quantum Physics · Physics 2013-08-26 Teck Seng Koh , John King Gamble , Mark Friesen , M. A. Eriksson , S. N. Coppersmith

In this theoretical manuscript I propose a scheme for entangling a single electron semiconductor spin qubit with a single electron semiconductor charge qubit in a triangular triple quantum dot configuration. Two out of three quantum dots…

Mesoscale and Nanoscale Physics · Physics 2022-03-30 Marko J. Rančić

We provide a physical analysis of the charging and detection of the first few electrons in a laterally-coupled GaAs/AlGaAs quantum dot (LCQD) circuit with integrated quantum point contact (QPC) read-out. Our analysis is based on the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 L. -X. Zhang , P. Matagne , J. P. Leburton , R. Hanson , L. P. Kouwenhoven

Achieving stable, high-quality quantum dots has proven challenging within device architectures rooted in conventional solid-state device fabrication paradigms. In fact, these are grappled with complex protocols in order to balance ease of…

Mesoscale and Nanoscale Physics · Physics 2024-06-25 Domenic Prete , Valeria Demontis , Valentina Zannier , Lucia Sorba , Fabio Beltram , Francesco Rossella

It has been experimentally shown that negative exchange interactions can arise in a linear three-dot system when a two-electron double quantum dot is exchange coupled to a larger quantum dot containing on the order of one hundred electrons.…

Mesoscale and Nanoscale Physics · Physics 2018-06-05 Kuangyin Deng , F. A. Calderon-Vargas , Nicholas J. Mayhall , Edwin Barnes

We analyzed the localized charge dynamics in the system of $N$ interacting single-level quantum dots (QDs) coupled to the continuous spectrum states in the presence of Coulomb interaction between electrons within the dots. Different dots…

Mesoscale and Nanoscale Physics · Physics 2013-07-09 Vladimir Mantsevich , Natalya Maslova , Petr Arseyev