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Spin qubits hosted in silicon (Si) quantum dots (QD) are attractive due to their exceptionally long coherence times and compatibility with the silicon transistor platform. To achieve electrical control of spins for qubit scalability, recent…

Valley-orbit coupling is a key parameter for a silicon quantum dot in determining its suitability for applications in quantum information processing. In this paper we study the effect of interface steps on the magnitude and phase of…

Mesoscale and Nanoscale Physics · Physics 2019-10-02 Bilal Tariq , Xuedong Hu

Proposed Silicon-based quantum computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing infrastructure of…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Belita Koiller , Xuedong Hu , S. Das Sarma

We show that the mixing between spin and valley degrees of freedom in a silicon quantum bit (qubit) can be controlled by a static electric field acting on the valley splitting $\Delta$. Thanks to spin-orbit coupling, the qubit can be…

Mesoscale and Nanoscale Physics · Physics 2018-05-02 Léo Bourdet , Yann-Michel Niquet

Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based…

Mesoscale and Nanoscale Physics · Physics 2014-08-05 Xiaojie Hao , Rusko Ruskov , Ming Xiao , Charles Tahan , HongWen Jiang

Quantum dots in SiGe/Si/SiGe heterostructures host coherent electron spin qubits, which are promising for future quantum computers. The silicon quantum well hosts near-degenerate electron valley states, creating a low-lying excited state…

Silicon-based metal-oxide-semiconductor quantum dots are prominent candidates for high-fidelity, manufacturable qubits. Due to silicon's band structure, additional low-energy states persist in these devices, presenting both challenges and…

Substitutional donor atoms in silicon are promising qubits for quantum computation with extremely long relaxation and dephasing times demonstrated. One of the critical challenges of scaling these systems is determining inter-donor distances…

The energy spectrum and wave functions of electrons in a single silicon quantum dot provide valuable insights into the capabilities and limitations of such a system in quantum information processing. Here we investigate the low-lying…

Mesoscale and Nanoscale Physics · Physics 2026-03-26 Bilal Tariq , Xuedong Hu

Donors in silicon, conceptually described as hydrogen atom analogues in a semiconductor environment, have become a key ingredient of many "More-than-Moore" proposals such as quantum information processing [1-5] and single-dopant electronics…

Mesoscale and Nanoscale Physics · Physics 2015-04-07 M. Fernando Gonzalez-Zalba , André Saraiva , Dominik Heiss , Maria J. Calderón , Belita Koiller , Andrew J. Ferguson

Excitations of impurity complexes in semiconductors can not only provide a route to fill the terahertz gap in optical technologies, but can also connect local quantum bits to scale up solid-state quantum-computing devices. However, taking…

Mesoscale and Nanoscale Physics · Physics 2021-08-04 Wei Wu , A. J. Fisher

We present a complete theoretical treatment of Stark effects in doped silicon, whose predictions are supported by experimental measurements. A multi-valley effective mass theory, dealing non-perturbatively with valley-orbit interactions…

The valley splitting of 2D electrons in doubly-gated silicon-on-insulator quantum wells is studied by low temperature transport measurements under magnetic fields. At the buried thermal-oxide SiO$_{2}$ interface, the valley splitting…

Mesoscale and Nanoscale Physics · Physics 2025-09-03 Nathan Aubergier , Vincent T. Renard , Sylvain Barraud , Kei Takashina , Benjamin A. Piot

The valley splitting (VS) of a silicon quantum dot plays an important role for the performance and scalability of silicon spin qubits. In this work we investigate the VS of a SiGe/Si/SiGe heterostructure as a function of the size and…

Mesoscale and Nanoscale Physics · Physics 2024-05-07 Jonas R. F. Lima , Guido Burkard

The energies of valley-orbit states in silicon quantum dots are determined by an as yet poorly understood interplay between interface roughness, orbital confinement, and electron interactions. Here, we report measurements of one- and…

Electronic spins in Silicon (Si) are rising contenders for qubits -- the logical unit of quantum computation-- owing to its outstanding spin coherence properties and compatibility to standard electronics. A remarkable limitation for spin…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 Lijun Zhang , Jun-Wei Luo , A. L. Saraiva , Belita Koiller , Alex Zunger

Phosphorus donor spins in silicon offer a number of promising characteristics for the implementation of robust qubits. Amongst various concepts for scale-up, the shared-control concept takes advantage of 3D scanning tunnelling microscope…

Quantum Physics · Physics 2021-07-27 Charles D. Hill , Muhammad Usman , Lloyd C. L. Hollenberg

The presence of non-degenerate valley states in silicon can drastically affect electron dynamics in silicon-based heterostructures, leading to electron spin relaxation and spin-valley coupling. In the context of solid-state spin qubits, it…

Mesoscale and Nanoscale Physics · Physics 2020-11-18 Nicholas E. Penthorn , Joshua S. Schoenfield , Lisa F. Edge , HongWen Jiang

We report electronic transport measurements through a silicon hybrid double quantum dot consisting of a donor and a quantum dot. Transport spectra show resonant tunneling peaks involving different valley states, which illustrate the valley…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 T. Kobayashi , J. van der Heijden , M. G. House , S. J. Hile , Pablo Asshoff , M. F. Gonzalez-Zalba , M. Vinet , M. Y. Simmons , S. Rogge

Valley splitting is a key figure of silicon-based spin qubits. Quantum dots in Si/SiGe heterostructures reportedly suffer from a relatively low valley splitting, limiting the operation temperature and the scalability of such qubit devices.…