Dipole-dipole interaction in quantum logic gates and quantum reflection - PowerPoint PPT Presentation

About This Presentation
Title:

Dipole-dipole interaction in quantum logic gates and quantum reflection

Description:

EVANESCENT-WAVE ATOMIC MIRRORS ... Evanescent waves. A. Landragin, J.-Y. ... Quantum reflection from evanescent-wave atomic mirrors occurs at finite energies, ... – PowerPoint PPT presentation

Number of Views:57
Avg rating:3.0/5.0
Slides: 32
Provided by: william499
Category:

less

Transcript and Presenter's Notes

Title: Dipole-dipole interaction in quantum logic gates and quantum reflection


1
Dipole-dipole interaction in quantum logic gates
and quantum reflection
  • Angela M. Guzmán
  • Departamento de Física, Universidad Nacional de
    Colombia, Bogotá, Colombia, and visiting
    Professor,
  • School of Physics, The Georgia Institute of
    Technology, Atlanta, GA 30332, USA.
  • angela.guzman_at_guzgon.com.

2
1. Quantum dipole-dipole interaction
2. Controlled collisions between neutral atoms.
s-scattering .vs. dipole-dipole interaction in
a phase gate.
Marco Dueñas, Universidad Nacional de Colombia
3. van der Waals interaction in an external
field Quantum reflection in evanescent-wave
mirrors static .vs. dynamic van der Waals
(dipole-dipole) potential.
Brian Kennedy, Georgia Institute of Technology.
3
DIPOLE-DIPOLE INTERACTION
4
DIPOLE-DIPOLE INTERACTION
Controlled collisions between adjacent atoms in
an optical lattice
Atom-wall interaction in quantum reflection
Cold atoms
Wannier functions
5
s-scattering (Fermi Potential)
D. Jaksch, H.-J. Briegel, J. I. Cirac, C. W.
Gardiner, and P. Zoller. Phys. Rev. Lett. 82,1975
(1999).
6
A 1D moving optical lattice (with
polarization gradient)
7
Optical potential U,U-
2U0
U0
0
0
1.6
0.8
kLz
8
Controlled Collisions
CONTROLLED COLLISION
9
DIPOLE-DIPOLE INTERACTION
Atom 1
Atom 2
K2
K1
k
k
VACUUM PHOTONS
Induced dipole -moment.
10
Selection rules
Transition probabilities
Elastic collisions
11
(No Transcript)
12
Elastic collisions, dipole-dipole interaction
Interaction energy
Spatially modulated losses.
13
MATRIX ELEMENTS
14
Interaction energy
15
ImDipole-Dipole interaction potential
16
ORDERS OF MAGNITUDE
  • The probability losses (probability of having
    the
  • atoms in the original two-qubit state)

Adiabatic criterion
17
Using a commutation frequency b3
18
Remarks
  • Long range potentials rather than s-scattering
    determine the table of truth of logic gates based
    on atomic collisions.
  • Logic operations based in the dipole-dipole
    interaction can not be performed in a time scale
    shorter than that of the spatially modulated
    losses.
  • Dissipation diminishes fidelity and does not
    allow for successive quantum operations.
  • Same limitations apply to schemes with enhanced
    dipole-dipole interaction G. K. Brennen, C. M.
    Caves, P. S. Jessen, and I. H. Deutsch, Phys.
    Rev. Lett. 82, 1060 (1999), unless special
    bichromatic engineering is used to balance
    losses.


19
Atom-wall interaction in atomic reflection the
dipole-dipole interaction
  • J.E. Lennard-Jones, Trans. Faraday Soc. 28,33
    (1932).

Perfect conductor
Perfect conductor
Perfect conductor
r
r
r
r
r
r
r
r
20
  • H.B. Casimir and D. Polder, Phys. Rev. 73, 360
    (1948). Radiative corrections

21
ALKALI ATOMS GOLD SURFACE
Exp. 1 Theor. 2
Cs 1.087 4.143 0.59
Rb 0.938 3.362 0.65
K 0.791 2.877 0.73
3
1 A. Shih, V.A. Parsegian , Phys. Rev. A 12,
835 (1975) 2 A. Derevianko, W. R. Johnson, M.
S. Safranova, J. F. Babb Phys. Rev. Lett.
82, 3589 (1999). 3 F. Shimizu, Phys. Rev.
Lett. 86, 987 (2001) (Neon)
22
QUANTUM REFLECTION
Na BEC
T. A. Pasquini, Y-I Shin, C. Sanner, M. Saba, A.
Schirotzek, D.E. Pritchard, and W. Ketterle,
arXiv.org/cond-mat/0405530.
23
EVANESCENT-WAVE ATOMIC MIRRORS
M. Kasevich, K. Moler, E. Riis, E. Sunderman, D.
Weiss, and S. Chu, Atomic Physics 12, AIP
Conf. Proc. 233, 47 (1991).
A means of measuring atom-surface forces
24
DIPOLE-DIPOLE INTERACTION
25
Dynamic van der Waals potential between a ground
state atom and a dielectric surface in the
presence of an evanescent wave and the EM vacuum.
Dissipation
Dynamic Potential
26
Dissipation due to the interaction through the
vacuum
27
Dynamic van der Waals potential
Static van der Waals potential
28
Effective potential
Optical potential
Dynamic van der Waals potential
Effect of van der Waals potential
29
Quantum reflection
  • Evanescent waves. A. Landragin, J.-Y. Courtois,
    G. Labeyrie, N. Vansteenkiste, C. I. Westbrook,
    and A. Aspect, Phys. Rev. Lett. 77, 1464 (1996).

From a solid surface at normal incidence. T. A.
Pasquini, Y-I Shin, C. Sanner, M. Saba, A.
Schirotzek, D.E. Pritchard, and W. Ketterle,
arXiv.org/cond-mat/0405530.
30
Quantality of the potentials
q
31
Remarks
  • Atom-wall and atom-atom van der Waals potential
    in external fields relate to the dynamic rather
    than to the static polarizability.
  • The shape of the reflecting potential is not
    controlled by S0 alone. Variations in field
    intensity scale the potential but variations in
    detuning shift the maximum.
  • Quantum reflection from solid surfaces occurs
    only for atomic velocities close to zero (heating
    has been observed). Quantum reflection from
    evanescent-wave atomic mirrors occurs at finite
    energies, but the reflectivity will be less than
    one because of dissipative effects.
  • Applications in atomic funnels, quantum
    reflection engineering, optical traps for quantum
    gases, Rydberg atoms in optical lattices (a power
    dependent line width of the fluorescence spectrum
    has already been observed, FiO 2004).
Write a Comment
User Comments (0)
About PowerShow.com