Pelle Grin

of 9/9
8/14/2019 Pelle Grin http://slidepdf.com/reader/full/pelle-grin 1/9  Decoherence protection and quantum logic gates in photonic bandgap structures Sophie Pellegrin, Gershon Kurizki Chemical Physics Department Weizmann Institute of Science Rehovot 76100, Israel [email protected] www.weizmann.ac.il Quantum information – optically manipulated atoms Challenge: protection of the quantum states from decoherence – spontaneous emission Photonic crystals – photonic bandgap structures Quantum logic gates: dynamical aspects adiabatic / nonadiabatic Periodic sudden changes Decoherence protection and quantum logic gates in photonic bandgap structures Sophie Pellegrin, Gershon Kurizki Chemical Physics Department Weizmann Institute of Science Rehovot 76100, Israel [email protected] www.weizmann.ac.il Quantum information – optically manipulated atoms Challenge: protection of the quantum states from decoherence – spontaneous emission Photonic crystals – photonic bandgap structures Quantum logic gates: dynamical aspects adiabatic / nonadiabatic Periodic sudden changes
  • date post

    30-May-2018
  • Category

    Documents

  • view

    229
  • download

    0

Embed Size (px)

Transcript of Pelle Grin

  • 8/14/2019 Pelle Grin

    1/9

    Decoherence protection and quantum logic gatesin photonic bandgap structures

    Sophie Pellegrin, Gershon Kurizki

    Chemical Physics DepartmentWeizmann Institute of Science

    Rehovot 76100, Israel

    [email protected]

    Quantum information optically manipulated atomsChallenge: protection of the quantum states from decoherence spontaneous emission

    Photonic crystals photonic bandgap structures

    Quantum logic gates: dynamical aspectsadiabatic / nonadiabatic

    Periodic sudden changes

    Decoherence protection and quantum logic gatesin photonic bandgap structures

    Sophie Pellegrin, Gershon Kurizki

    Chemical Physics DepartmentWeizmann Institute of Science

    Rehovot 76100, Israel

    [email protected]

    Quantum information optically manipulated atomsChallenge: protection of the quantum states from decoherence spontaneous emission

    Photonic crystals photonic bandgap structures

    Quantum logic gates: dynamical aspectsadiabatic / nonadiabatic

    Periodic sudden changes

    http://www.weizmann.ac.il/http://www.weizmann.ac.il/http://www.weizmann.ac.il/http://www.weizmann.ac.il/
  • 8/14/2019 Pelle Grin

    2/9

    Photonic crystals

    1D

    2D

    3D

    photonic crystals - light

    periodic refractive index

    semi conductors - electrons

    periodic atomic potential

    Band structure

    K. Lim et al., GaAs and AlGaAs 1.8 m, =4.5 m and 1.5 m

    AIST, Japan, TiO2 pillars of

    640 nm and height 2 m

    Fan et al., Si (dark) and SiO2 (light), large

    and complete submicron bandgap.

    S. G. Johnson and J. D. Joannopoulos,APL 77, 3490-3492 (Nov. 2000)

    J. G. Fleming and S. Y. Lin,Opt. Lett. (1999)

  • 8/14/2019 Pelle Grin

    3/9

    Defects

    Breaking the periodicity point like defects: cavities

    frequency

    bandgap

    linear defects: waveguide

    90 bend: 98 of the power transmission(30 in analogous dielectric waveguide)

    2 m

  • 8/14/2019 Pelle Grin

    4/9

    Density of modes

    Neglecting the vectorial nature of the electromagnetic field:analytic scalar dispersion relation

    isotropic density of modes (gap = sphere) ( - c)-1/2

    qualitative results, limited to the description of the bandgap neighborhood

    Quantitative results: non isotropic density

    Densityo

    fmodes

    2

    c

    Scalar, isotropic approximation

    c

  • 8/14/2019 Pelle Grin

    5/9

    Coupling with an atom static aspects

    0.0 10.0 20.0 30.00.2

    0.4

    0.6

    0.8

    1.0

    time (dimensionless(

    Excit

    edstatep

    opulatio

    n

    A. G. Kofman, G. Kurizki, B. Sherman, J. of Mod. Opt. 41, 353 (1994)

    Stronginteraction between the atomand its own photon : splitting

    of the atomic transitionone part is stable, the other one decays.

    Static position of the atomic transition inside the gap.

    at

  • 8/14/2019 Pelle Grin

    6/9

    dyn (t) = Astat ( ) B

    stat (t- ) +

    ,Astat ( ) ,Bstat (t- ) ( ) d , t0+

    Dynamic aspects periodic shifts (1)

    time (dimensionless(

    Excite

    dstatepop

    ulation

    A B

    B

    A

    A

    B

    static

    densityof modes

    A

    B

    A/Bstat = excited state amplitude

    at a fixed frequency A ( B)

    ,A/Bstat = mode amplitude

    0 20 40 600.6

    0.7

    0.8

    0.9

    1.0

    Exciteds

    tatepopulation

    time (dimensionless(

    static

    one change

  • 8/14/2019 Pelle Grin

    7/9

    Dynamic aspects periodic shifts (2)

    0 20 400.65

    0.75

    0.85

    0.95

    Excitedstatepo

    pulation

    time (dimensionless(

    densityof modes

    A

    B

    0 20 0.65

    0.75

    0.85

    0.95

    Exciteds

    tatepopulation

    time (dimensionless(

    Finite transition times

    0 5 10 150.0

    0.2

    0.4

    0.6

    0.8

    1.0

    fid

    elity

    time (dimensionless(

    gate

    control phase gate:excited atomic statephase shift of / 2performed adiabatically

    8 9 10 110.90

    0.95

    fid

    elity

    time (dimensionless(

  • 8/14/2019 Pelle Grin

    8/9

    Conclusion and perspectives

    Periodic modulation of the detuning is able to protect the atomic statefrom spontaneous emission more effectively

    than fixing the largest possible detuning value

    Sudden changes outperform the adiabatic modulation

    First attempts to apply the resultsto quantum logic gates are very encouraging

  • 8/14/2019 Pelle Grin

    9/9