Abstract
| Original language | Undefined |
|---|---|
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| Award date | 24 Mar 2016 |
| Place of Publication | Enschede |
| Publisher | |
| Print ISBNs | 978-90-365-4082-7 |
| DOIs | |
| Publication status | Published - 24 Mar 2016 |
Keywords
- METIS-316214
- EWI-27016
- IR-100012
Cite this
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Hole spins in GE-SI nanowires. / Brauns, M.
Enschede : Universiteit Twente, 2016. 82 p.Research output: Thesis › PhD Thesis - Research UT, graduation UT › Academic
TY - THES
T1 - Hole spins in GE-SI nanowires
AU - Brauns, M.
PY - 2016/3/24
Y1 - 2016/3/24
N2 - In a universal quantum computer, coherent control over the state of a quantum mechanical two-level system is needed. This requires interactions of the quantum state with its environment. Inherently, such interactions also lead to decoherence and thus limit the performance of the quantum computer. A profound knowledge of the relevant interaction mechanisms is therefore key to the realization of a quantum computer. In this thesis we use Ge-Si core-shell nanowires to investigate holes confined to one dimension. Mixing of heavy and light hole states leads to a strong, anisotropic spin-orbit interaction in this system. We define highly stable quantum dots of different lengths in the nanowire and controllably split up longer quantum dots into double quantum dots. The effective g-factor in these one-dimensional hole quantum dots is found to be highly anisotropic with respect to the nanowire axis as well as the electric-field axis. In double quantum dots, we observe shell filling of new orbitals and Pauli spin blockade of the second hole entering the orbital. The leakage current in the spin-blocked state is highly anisotropic with spin-flip cotunnelling as the dominant leakage mechanism. At finite magnetic fields, we also find signatures of leakage current induced by spin-orbit coupling and anisotropic Coulomb effects.
AB - In a universal quantum computer, coherent control over the state of a quantum mechanical two-level system is needed. This requires interactions of the quantum state with its environment. Inherently, such interactions also lead to decoherence and thus limit the performance of the quantum computer. A profound knowledge of the relevant interaction mechanisms is therefore key to the realization of a quantum computer. In this thesis we use Ge-Si core-shell nanowires to investigate holes confined to one dimension. Mixing of heavy and light hole states leads to a strong, anisotropic spin-orbit interaction in this system. We define highly stable quantum dots of different lengths in the nanowire and controllably split up longer quantum dots into double quantum dots. The effective g-factor in these one-dimensional hole quantum dots is found to be highly anisotropic with respect to the nanowire axis as well as the electric-field axis. In double quantum dots, we observe shell filling of new orbitals and Pauli spin blockade of the second hole entering the orbital. The leakage current in the spin-blocked state is highly anisotropic with spin-flip cotunnelling as the dominant leakage mechanism. At finite magnetic fields, we also find signatures of leakage current induced by spin-orbit coupling and anisotropic Coulomb effects.
KW - METIS-316214
KW - EWI-27016
KW - IR-100012
U2 - 10.3990/1.9789036540827
DO - 10.3990/1.9789036540827
M3 - PhD Thesis - Research UT, graduation UT
SN - 978-90-365-4082-7
PB - Universiteit Twente
CY - Enschede
ER -