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Dynamical decoupling in solids

Dynamical decoupling in solids. 报告人：王亚 导师：杜江峰. University of Science & Technology of China. 2011.8.5. Outline. Suppressing decoherence Anomalous decoherence effect The application of DD in quantum metrology Future work. Decoherence suppression with DD. decoherence.

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Dynamical decoupling in solids

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  1. Dynamical decoupling in solids 报告人：王亚 导师：杜江峰 University of Science & Technology of China 2011.8.5

  2. Outline • Suppressing decoherence • Anomalous decoherence effect • The application of DD in quantum metrology • Future work

  3. Decoherence suppression with DD decoherence Decoherence suppression

  4. Hahn spin echo echo time π time

  5. Spin bath system ……

  6. Decoupling sequences

  7. Impurity spin-based Quantum computer [NV]-center in diamond Endohedral N@C60 External field P doped in silicon N S = 3/2 S = 1 S = 1/2 ……

  8. Magnetic Field B Electron Orbit Crystal Lattice Nuclear spin Nuclear spin Electron spin Electron spin Interactions in an Electron Spin-Nuclear Bath Coupling Solid State Computer Spin-orbital Hyperfine: Fermi Contact Dipole-Dipole Dipole-Dipole Dipole-dipole

  9. Typical electron spin decoherence time in solids T1>>T2, spin bath is the main decoherence source

  10. Qubit-bath model for pure dephasing Nuclear spin interaction (dipole-dipole, Zeeman energy, etc.) Zeeman energy Overhauser field A block diagonal Hamiltonian for qubit

  11. Decoherence by quantum entanglement

  12. Decoherence under Dynamical decouling

  13. DD under simulated noise Michael J. Biercuk et al. Nature 458 996 (2009)

  14. DD in solids: ensemble system • J.F Du et al. Nature 461 1265 (2009) After 7 pulses, the coherence enhancement is saturated due to the electron-electron spin coupling.

  15. DD in solids: single electron spin G. Lange et. Al., Science 330, 60 (2010) Up to 136 pulses, no limit is found to the coherence enhancement

  16. Pulse imperfections in DD C.A.Ryan et al. Phys. Rev. Lett 105, 200402 (2010)

  17. Dynamical decoupling works in muti-qubit case ?

  18. Nested DD in multi-qubits case Physical Review A 81, 012331(2010) Physical Review A 82, 052338(2010) Commute or anti-commute Single qubit operators, e.g. Phys. Rev. A 83, 022306 (2011) … … … … … … … …

  19. CW/Pulsed EPR sepctrometer

  20. Anomalous Decoherence Effect in a Quantum Bath

  21. 3E Nitrogen Vacancy (NV) in Diamond Laser B N V MW C C C 1μm C C C 3A2 kcounts/s Fluorescence Optical Excitation

  22. 3E Energy level 1A1 3A2 ms=-1 ms=1 ODMR spectrum Rabi Oscillation ms=0

  23. ODMRsetup

  24. Optical Parts

  25. Microwave and Electronic parts

  26. Quantum Description of decoherence • Coherence is lost as which-way • information is recorded in the bath 3 ways for nuclear spin of different electron state

  27. Decoherence without DD Observation of free induced decay of single- and multi-transition in NV

  28. Anomalous Decoherence Effect in Muti-pulse DD

  29. Quantum Nature of ADE in single transition (0,+) case: in double transition (+,-) case: demolished due to DD control bath operator back action: cause high frequency moise

  30. Application of dynamical decoupling in Quantum metrology

  31. Standard quantum limit and Heisenberg limit Vittorio Giovannetti et al. PRL 96, 010401 (2006)

  32. An example

  33. Quantum metrology with entanglement J. M. Geremia, J. K. Stockton, H. Mabuchi, Science 304,270 (2004); D. Leibfried , et al., Nature 438, 639 (2005); Tomohisa Nagata, et al.Science 316, 726 (2007); Jonathan A. Jones, et al., Science 324, 1166 (2009) C. Gross, et al . , Nature 464, 1165-1169(2010); ……

  34. Quantum metrology without entanglement:Multi-round protocol Vittorio Giovannetti et al. PRL 96, 010401 (2006) • B.L.Higgins et al. Nature 450 393 (2007)

  35. Geometric phase(GP):AA phase [NV]-center in diamond S = 1

  36. Addressing NV centre

  37. Phase estimation with single GP

  38. Phase estimation with multi GP Repeated N times Prepare Read out Prepare Read out Classical: Repeated N times φ φ Quantum:

  39. Enhanced phase estimation with CPMG k GP 2k GP k GP π π π π π π π π π π π π/2 π/2

  40. Analysis

  41. Future work • Robust gate • Dynamically corrected gate(DCG) PRL 102,080501(2009)… • Combine DD with optimization control • …

  42. Thank you for your attention

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