Upload
jiajun898
View
228
Download
0
Embed Size (px)
Citation preview
7/30/2019 Eqec2011 Gleb
1/13
Atom-Light Interface in Strong
Focusing GeometrySyedAbdullah Aljunid, Jianwei Lee,
Kadir Durak, Brenda Chng,
Martin Paesold, Dao Hoang Lan,Gleb Maslennikov, Christian Kurtsiefer
Theory support: Yimin Wang, Teo Zhi Wei Colin,
Lana Sheridan,Valerio Scarani,
CLEO 2011, Europe, Munich EA 9.2
7/30/2019 Eqec2011 Gleb
2/13
Atom-Photon Interface
Quantum Information and Communication protocols
information exchange between flying qubits (photons) and
stationary qubits (atoms)
absorptiontriggered
phase shift
7/30/2019 Eqec2011 Gleb
3/13
Strong Coupling
V=deffEA E(x , t)=i g(x )a (t)+g* (x) a(t)
Interaction Electric field operator (single mode)
normalizationmode function
=
20Vm
Vm= dxg(x)mode volume
paraxial beams with
gaussian mode function
Vm=Lw0
2
2
=
w02
L0
Strong coupling in a Jaynes-Cummings model
g0=deff=
32c
w02
L
LOSSES
7/30/2019 Eqec2011 Gleb
4/13
Reference
15 1.5 2x105M. Koch et. al.,
Phys. Rev. Lett. 105,173003 (2010)
12 0.4 106T. Kampschulte et.al.,Phys. Rev. Lett.105, 153603 (2010)
215 53 4x104R.Gehr et. al.,
Phys. Rev. Lett. 104,203602 (2010)
Cavities
Cavity to compensate for losses
g0
g0 , State of art values
g0
(2)MHz
(2)MHz Finesse
? can we go for even lower finesse to achieve strong coupling ? =
w0
2L
0
Focusing !?S.E. Morrin et al., Phys.Rev. Lett 73, 1489 (1994)
Confocal cavity with w0
Finesse=4.5,=(2)540MHz
g0=(2)32MHz
Finesse enough to observecavity mediated changes in
spontaneous emission
7/30/2019 Eqec2011 Gleb
5/13
Strong Focusing
? what is the maximal coupling one can achieve with strong focusing ?
? what is the maximum field at the focus EA, related to input field EL?
EL
EA
Lw
f
analytical solution for field at the focus gives (M.K.Tey et.al., NJP, 11, 043209 (2011))
( )uRw
uu
ue
u
w
E
Esc
LuL
L
A
2
222
22
2
32
222
3
1,
4
11,
4
1
4
3
3
2
=
+
=
f
wu
L
=
7/30/2019 Eqec2011 Gleb
6/13
Strong Focusing
The normalization constant for a
strongly focused mode becomes
=Rsc(u)
32L
0
and the coupling strength for anatom in an antinode of cavity's
standing wave is
g0=
c Rsc(u)
L
=27ns ,L=10mm
Current experiments on strong focusing
u0.35L=6mm,g 0(2)40MHz
Strong coupling expected for
(2)10MHzR0.99
7/30/2019 Eqec2011 Gleb
7/13
Cavity lenses
f n
n+1
fn1n+1
longitudinal half-axis
transverse half-axis
I. Sahl, On burning mirrors and lenses(Publisher unknown, Baghdad, 984)
prototype lens turned from PMMA bySYNTEC OPTICS
surface irregularity < 100 angstrom
sag error (spherical surface) 300 nm
wavefront deviations ~/10 PV
Work in progress!
NA = 0.35
7/30/2019 Eqec2011 Gleb
8/13
Caveats I
Single-mode optical cavity with small waist --- need to work near stability threshold
testing with a different cavity, L = 10 cm, Rc=- 5 cm, R = 0.97, F = 150
w0
2=
2L(2RcL) w0=7.5 m , g0=(2)5.3 MHz ,=(2)16MHz
Ways to go: decrease L further, make more tests on stability in vacuum
7/30/2019 Eqec2011 Gleb
9/13
Caveats II
Atom has to be well localized at the antinode of the standing wave
In our experiments we trap87
Rb atom in a tightly focused optical tweezer
trap frequencies
=55 kHz ,l=7 kHz ,
Raman cooling of an atom to the ground state of the trap can be performed
7/30/2019 Eqec2011 Gleb
10/13
Raman Cooling
average motional stateafter cooling
n =0.550.07
atomic delocalization
x200 nm
x
7/30/2019 Eqec2011 Gleb
11/13
Conclusions
A model describing optical resonators with a strongly
focused mode is proposed. An analytical expressionis obtained for the coupling strength, beyond paraxial
approximation.
We have designed an anaclastic cavity lens with
NA=0.3 that can be used in cavity QED experiments
with strong focusing
To achieve maximal coupling strength a thermal
Motion of atoms must be minimized.We have performed a Raman sideband cooling of single
87Rb atom in a tightly focusing dipole trap to
n =0.550.07
7/30/2019 Eqec2011 Gleb
12/13
Thank you!
Syed Abdullah Aljunid
Jianwei LeeKadir Durak
Martin PaesoldDao Hoang Lan
Brenda ChngGleb Maslennikov
Yimin WangColin Teo
Lana Sheridan
Valerio ScaraniChristian Kurtsiefer
7/30/2019 Eqec2011 Gleb
13/13
Single atom
(almost) Hanbury-BrownTwiss experiment on
atomic fluorescence during cooling
Rabioscillation
photon
antibunchingD1
D2