Abstract
Original language  Undefined 

Awarding Institution 

Supervisors/Advisors 

Thesis sponsors  
Award date  24 Mar 2016 
Place of Publication  Enschede 
Publisher  
Print ISBNs  9789036540827 
DOIs  
Publication status  Published  24 Mar 2016 
Keywords
 METIS316214
 EWI27016
 IR100012
Cite this
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Hole spins in GESI 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 GESI 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 twolevel 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 GeSi coreshell nanowires to investigate holes confined to one dimension. Mixing of heavy and light hole states leads to a strong, anisotropic spinorbit 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 gfactor in these onedimensional hole quantum dots is found to be highly anisotropic with respect to the nanowire axis as well as the electricfield 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 spinblocked state is highly anisotropic with spinflip cotunnelling as the dominant leakage mechanism. At finite magnetic fields, we also find signatures of leakage current induced by spinorbit coupling and anisotropic Coulomb effects.
AB  In a universal quantum computer, coherent control over the state of a quantum mechanical twolevel 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 GeSi coreshell nanowires to investigate holes confined to one dimension. Mixing of heavy and light hole states leads to a strong, anisotropic spinorbit 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 gfactor in these onedimensional hole quantum dots is found to be highly anisotropic with respect to the nanowire axis as well as the electricfield 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 spinblocked state is highly anisotropic with spinflip cotunnelling as the dominant leakage mechanism. At finite magnetic fields, we also find signatures of leakage current induced by spinorbit coupling and anisotropic Coulomb effects.
KW  METIS316214
KW  EWI27016
KW  IR100012
U2  10.3990/1.9789036540827
DO  10.3990/1.9789036540827
M3  PhD Thesis  Research UT, graduation UT
SN  9789036540827
PB  Universiteit Twente
CY  Enschede
ER 