Quantum logic gate based on a single walled carbon nanotube containing spin elements at S1 and S2.

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Nanotube quantum logic gate

• Quantum logic gate based on a single walled
  carbon nanotube containing spin elements at S1
  and S2.

A. Ardavan et al., Phil. Trans. R. Soc. Lond. A
361, 1473-1485 (2003)
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Spin qubits in carbon nanomaterials
Quantum Nanoscience, Noosa Heads22nd 26th
January 2006www.qipirc.org
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Quantum Information Processing IRC
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Fundamental concepts in quantum mechanics

• 1930s Philosophical debate
• Hidden variables vs non-locality
• Copenhagen interpretation
• 1970s Experimental verification
• Bell inequality (1966)
• Experimental Test of Local Hidden-Variable
  Theories Stuart J. Freedman and John F. Clauser
  (1972)
• 2010s Technological implementation
• Quantum cryptography
• Quantum metrology
• Quantum computing

www.qipirc.org
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Spin qubits in carbon nanomaterials

• What we still need to know
• How could you measure an individual qubit?
• What would the nature of the interactions be?
• How would you address and control qubits that are
  so closely spaced?
• Is a 1-D quantum circuit adequate for robust
  quantum computing?
• What we have learned
• Chemistry provides a marvellous tool for
  molecular assembly of hierarchical quantum
  nanomaterials.
• We can model their structural and electronic
  properties rather accurately.
• Molecular nanomaterials offer well-defined and
  reproducible energy levels and selection rules.
• We can manipulate individual electron and nuclear
  spins with exquisite precision.

www.qipirc.org
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Fullerenes in nanotubes
Gas-Phase Nanotube Filling (300-500oC)

Fullerene C60, C70, C82, Sc_at_C82, Ce_at_C82,
Nd_at_C82 Sc2_at_C80, Ce2_at_C80, Er3N_at_C80, Sc3N_at_C80
Nanotubes (diameters 1.36nm and 1.49nm)
www.nanotech.org
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Fullerene molecules in carbon nanotubes

• (a, b) C60_at_DWNTs zigzag
• (c, d) C60_at_SWNT chiral
• (e, f) two-molecule layer

Simulated annealing Hodak and Girifalco Phys Rev
B 67, 075419 (2003)
A.N. Khlobystov et al. Phys. Rev. Lett. 92,
245507 (2004)
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10 yoctolitre test tubes
Chemical reactions inside single-walled carbon
nano test-tubes. Chem. Commun. 2005, 37-39
(2005) Hot Paper (19 November 2004) cover story
of Issue 1 of 40th Anniversary Year Blueprint 5,
3 (18 November 2004) New Scientist (23 November
2004) BBC News Iran Daily Newspaper (25 November
2004) p. 4 Financial Times 35621, 13 (26 November
2004) Chemical Engineering News 82 (48) 7 (29
November 2004) Chemistry World 12 (December
2004) Editors Choice, Science 306, 1863 (10
December 2004) Smallest reactor ever, Materials
Today 8 (1) 9 (January 2005) The smallest test
tube in The Guinness Book of World Records (2006)
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10 yoctolitre test tubes
Chemical reactions inside single-walled carbon
nano test-tubes. D.A. Britz et al., Chem.
Commun. 2005, 37-39.
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Ce_at_C82_at_SWNT
A. Khlobystov et al. Angewandte Chemie
International Edition 43, 1386-1389 (2004, hot
paper)
5 nm
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PLE of Er3N_at_C80
Mark Jones
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Sc_at_C82 hyperfine coupling /mT
HFC /mT Expt (ESR) Theory (DFT)
Sc 0.382 0.280 (-33)
13C 0.177 0.153 (-24)
0.38 mT
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Sc_at_C82 what is the electronic structure?
G.W. Morley et al., Nanotechnology 16, 2469-2473
(2005) Your article Hyperfine structure of
Sc_at_C82 from ESR and DFT has been downloaded 500
times so far. This was achieved in 51 days from
the date of publication. To put this into
context, across all IOP journals 3 of articles
were accessed over 500 times this year. (3rd Nov
2005)
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Filling nanotubes using supercritical CO2
A.N. Khlobystov et al., J. Mater.
Chem. 14, 2852-2857 (2004)
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Fullerene molecules in nanotubes
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14N_at_C60 T1 and T2 vs Temperature
At 4.2 K, T1 gt 1 s
T1
T2
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BB1 sequence for spin manipulation
J.J.L. Morton et al., Phys. Rev. Lett. 95, 200501
(2005)
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14N_at_C60
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Dynamic nuclear polarisation of 15N_at_C60
Gavin Morley
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Bang-bang control
J.J.L. Morton et al., Nature Physics 2, 40-43
(2006)
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J.J.L. Morton et al., Nature Physics 2, 40-43
(2006)
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Bang-bang control
J.J.L. Morton et al., Nature Physics 2, 40-43
(2006)
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Spin qubits in carbon nanomaterials

• Goal
• To engineer a hierarchical molecular
  nanostructure exploiting quantum superposition
  and entanglement
• Achievement
• There is world wide progress in nanotube devices.
• Fullerenes can be arranged in nanotubes to make
  peapods with control over the phase of the
  packing
• Two qubit experiments have been demonstrated
  using electron and nuclear spins
• Aspiration
• Bring all these steps together to build a
  molecular QIP device

www.nanotech.org
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Bang-bang control
J.J.L. Morton et al., Nature Physics 2, 40-43
(2006)