QIC 890/891: A tutorial onNanowires in Quantum Information Processing
Daryoush Shiri, Institute for Quantum Computing (IQC)July 21, 23, 28 and 30, 2014
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Agenda• Introduction• A crash course on
• Electronic structure calculation• Phonon spectrum• Electron-phonon scattering
• Spin-Orbit Interaction• Rashba term• Dresselhaus term
• Exchange Interaction• Spin relaxation mechanisms
• Dyakonov - Perel• Elliot - Yafet• Hyperfine interaction
Daryoush Shiri, IQC 2
Introduction
Daryoush Shiri, IQC 3
• Electron spin is a natural choice for a Qubit.
• Spin of electrons in Quantum Dots (QD).
• QDs are defined by potential landscaping on 2DEG.
• 2DEG bandgap engineering in a superlattice.
Electric Field (spin-orbit interaction)
Spin to charge conversionESR
Nanowires & QIP
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• Semiconducting nanowires• A Host for embedding interacting Quantum Dots• Topology-based Q-Computing: Hunt for Majorana Fermions• Emitters of single photon, entangled photons
G. Weihs & H. Majedi, et al.
J. Baugh, IQC
L. Kouwenhoven, Delft
Superconducting nanowires• Detection of single photon (SNPD)
NIST
See courses offered by:Sir. Anthony Leggett and other faculty members at IQC and Physics on superconductivity
Why nanowires?
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• Compatibility with mainstream electronic chip industry• As opposed to 2DEG based Qdot systems:
Scalability of Qubits • Embedding many Qdots (spin qubits)• Better electrostatic control (potential landscape) using many gates
• Bandgap engineering
Fabrication methods
(2) Top-down methods
Group III-V (InP, InAs, InSb, GaAs, GaP, AlGaN,….)Group V (Si/Ge)Group II-VI (ZnSe/ZnTe)
(1) Bottom-up methods e.g. VLS
Review article by: J. Ramanujam, D. Shiri, and A. VermaMater. Express 1, 105-126 (2011).
Materials of Choice
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http://www.ioffe.rssi.ru/SVA/NSM/Semicond/
InAs InSb
m*/m0 = 0.023µe = 10,000 ~ 30,000 cm2/V.s @ base temp (100mK)Lande’ g-factor = 10λ MFP ~ 300nm
m*/m0 = 0.014µe = 10,000 ~ 30,000 @ base temp (100mK)Lande’ g-factor = 50
J. Baugh, IQC
InSb
Core-Shell
Tandem