Presentation on theme: "A NUCLEAR SPIN QUANTUM COMPUTER IN SILICON"— Presentation transcript:
1 A NUCLEAR SPIN QUANTUM COMPUTER IN SILICON Microanalytical Research CentreM A R CA NUCLEAR SPIN QUANTUM COMPUTER IN SILICONNational Nanofabrication Laboratory, School of Physics, University of New South WalesLaser Physics Centre, Department of Physics, University of QueenslandMicroanalytical Research Centre, School of Physics, University of Melbourne
2 MOTIVATIONQuantum Computers will be the world’s fastest computing devices, e.g. decryption (prime factors of a composite number) - Factor a 400 digit number 108 times fasterSpin-off technology development for conventional silicon processing at the sub-1000Å scale
5 QUANTUM LOGICAny quantum computation can be reduced to a sequence of 1 and 2 qubit operations:H |in> = H1 H2 H Hn |in>Conventional operations: NOT, AND Quantum operations: NOT, CNOT
6 QUANTUM ALGORITHMSSuperposition and entanglement enables massive parallel processingShor’s prime factorization algorithm (1994) relevant to cryptographyGrover’s exhaustive search algorithm (1996)QCCCFactoringQuantum Physics ProblemsExhaustive SearchNP-HardProblems?All Problems
7 EXPERIMENTAL QUANTUM COMPUTATION Bulk spin resonance (Stanford, MIT): ? qubitsTrapped cooled ions (Los Alamos, Oxford): ? qubitsTrue quantum computer may require 106 qubits“Solid state” (semiconductor) quantum computer architecturesProposed using electron and nuclear spin to store qubitsElectrons: D. Loss and D. DiVincenzo, Phys. Rev. A 57, 120 (1998).Nuclei: V. Privman, I. D. Vagner, and G. Kventsel, Phys. Lett. A in press, quant-ph/
8 In Si:P at Temperature (T)=1K: electron relaxation time = 1 hournuclear relaxation time = hours
9 A Silicon-based nuclear spin quantum computer B. E A Silicon-based nuclear spin quantum computer B. E. Kane, Nature, May 14, 1998~200 Å
11 Fabrication Pathways Fabrication strategies: (1) Nano-scale lithography:Atom-scale lithography using STM H-resistMBE growthEBL patterning of A, J-GatesEBL patterning of SETs(2) Direct 31P ion implantationSpin measurement by SETs or magnetic resonance force microscopyMajor collaboration with Los Alamos National Laboratory, funded through US National Security Agency
19 SUMMARY Quantum Computers have enormous potential Solid-state quantum computation is the best candidate for scalabilityOffers integration with existing Si technologyUNSW strategy to use qubits stored on nuclear spins (concept by Kane)
20 The Melbourne Node Node Team Leader: Steven Prawer Test structures created by single ion implantationAtom Lithography and AFM measurement of test structuresTheory of Coherence and Decoherence
22 Single Ion Implantation Fabrication Strategy Etch latent damage & metalliseRead-out state of “qubits”MeV 31P implantResist layerSi substrate
23 MeV ion etch pits in track detector Scale bars: 1 mm intervalsHeavy ion etch pitLight ion etch pitsSingle MeV heavy ions are used to produce latent damage in plasticEtching in NaOH develops this damage to produce pitsLight ions produce smaller pits1. Irradiate2. Latent damage3. EtchFrom: B.E. Fischer, Nucl. Instr. Meth. B54 (1991) 401.
24 Single ion tracksLatent damage from single-ion irradiation of a crystal (Bi2Sr2CaCuOx)Beam: 230 MeV AuLighter ions produce narrower tracks!Depth1 mm3 mm5 mm7.5 mm3 nmFrom Huang and Sasaki, “Influence of ion velocity on damage efficiency in the single ion target irradiation system” Au-Bi2Sr2CaCu2Ox Phys Rev B 59, p3862
25 Project Management - A distributed system Director ClarkDeputy Director MilburnReadoutTheory/ModellingArray fabricationSET DzurakMagnetic Resonance (LANL)Quantum Optics Rubeinstein-DunlopSingle Ion ImplantationJamiesonAtom LithographyPrawerSilicon MBESimmons
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