single atom wants to meet single photon · 2011. 1. 6. · deterministic source of single neutral...
TRANSCRIPT
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Single Atom wants to meet Single PhotonControlled Processes with Neutral Atoms
D. Meschede,
Institut für Angewandte Physik
Collège de FranceParis, Fevriér 26, 2002
Universität Bonn
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Single Atoms Crew
Dr.Victor GomerStephan KuhrWolfgang AltDominik SchraderMartin MüllerYephen Miroshnyshenko
Daniel Frese (`00)Bernd Ueberholz (`01)
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Experimenting with Single Neutral Atoms in a MOT
2. Deterministic Source ofSingle Neutral atoms
3. Single Atom Dynamics4. Towards entanglement
Overview
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Ernst Mach (1838-1916)
1867 Professor for Experimental Physics Prague1895 Professor for Philosophy Vienna
„Atome können wir nirgends wahrnehmen, sie sind wie alle Substanzen Gedankendinge.“
(„Atoms themselves cannot be perceived anywhere, like all substances they are abstractions.“ 1912)
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
2002:Physics/Quantum Optics is moving
towards Quantum Engineering!
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Experimenting with Single Neutral Atoms in a MOT
2. Deterministic Source ofSingle Neutral atoms
3. Single Atom Dynamics4. Towards entanglement
Overview
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Strong magnetic field helpsto better localise atoms
Magneto-optical Trap (MOT)
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Cesium atom „sixpack“
10 µm
Magneto-optical Trap (MOT)
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Clock 1
Detectors: APD (EG&G), 200ns dead time, Q.E. > 50%
Clocks: 50 ns resolution, ~ 1 MHz dyn. range
Magneto-optical Trap (MOT)
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Dynamics of trapped atoms
0 1 2 3 4 5 6 7 8 9 100
2
4
6
8
10
12
14
16
18
5 Atoms
Minutes
103 counts/100ms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Clock 1Clock 2
1. Experimenting with Single Neutral Atoms
Hanbury-Brown & Twiss setupImproves time resolution!
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Presto Internal Dynamics @ nano seconds2. Allegro Magnetic Bistability @ micro seconds3. Andante Global trap motion @ milli seconds4. Adagio Cold collisions @ seconds/minutes
Photon correlationsreveal atomic dynamics
at all relevant time scales!
1. Experimenting with Single Neutral Atoms
For a review see: V. Gomer and D. Meschede, Ann.Phys.(Leipzig)10, 9 –18 (2001) and refs. therein
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1 atom
0
1
2
3
Time [ns]0 40 80-40-80
Photon Antibunching – a Classic of Quantum Optics
Coi
ncid
ence
s/m
in„Prepares“ atom in ground state
Shows Rabi oscillation1. Photon
2. Photon
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3 atoms
10
0
5
coin
cid
en
ces/
min
0
4
8
2 atoms
1 atom
0
1
2
3
Time [ns]0 40 80-40-80
0 20 40 600,0
0,5
1,0ρ22
N = 1
N = 10
0 20 40 600,0
0,5
1,0
22
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Polarisation analysis
Clock 1Clock 2
Use linearly polarized light only!
PBS
l
r
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Strong circular correlations!
No linear correlations !
t [µs]0 20 40 60 80 100
1300
1400
1500
1600C
oinc
iden
ces/
100
ms l l
0 20 40 60 80 1000,0
0,2
0,4
0,6
0,8
1,0
t [µs]
lr
0 20 40 60 80 1000,0
0,2
0,4
0,6
0,8
1,0
1,2
g(2
)(τ
)vh
t [µs]
h v
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
r
Magnetic Bistability(Optical pumping in „real time“, µs time scale)
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
h
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
∆m = 1
∆m = 0
h
r
1. Experimenting with Single Neutral Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Experimenting with Single Neutral Atoms in a MOT
2. Deterministic Source ofSingle Neutral atoms
3. Single Atom Dynamics4. Towards entanglement
Overview
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
2. Deterministic Source of Cold Atoms
Controlling atomic dynamics:
• Impossible in the MOT• Use off resonant dipole trap!
SetupMOT
Nd:YAG laser
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Optical dipole potential = AC Stark effect
ground state
excited state
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
500 nm
U0=1.3 mK
z
Ωz
Optical dipole potential = AC Stark effect
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Laser SequenceMOTDipole Trap
N=0
N=2
N=4
N=3
0 10 20 30 40 50
Time [s]
Phot
on C
ount
s [1
00 k
Hz]
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Controlling theEXACT NUMBERof atoms
!!
SetupMOT
Nd:YAG laser
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
F=4
F=3
CesiumHyperfine structure
Controlling the internalQUANTUM STATEof single atoms !!
SetupMOT
Nd:YAG laser
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Towards controlling theEXACT POSITIONof single atoms !!
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
AOM
AOM
Loading Station for Single Atom Conveyor Belt
2. Deterministic Source of Cold Atoms
Photoncounter
Imaging optics
Nd:YAG-laser
MOTlaser beams
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
M OTr e gion
fix ed
detectio n
optic s
pro be
las er
di spl ace d
dete ctio noptics
a b
flu
ore
sc
en
ce
[co
un
ts/
20
ms]
0 50 100 15 0 20 0
0
10
20
30
tim e [ m s]
pr obe las er
Detection of relocated atoms
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
-2-4 0 2 4 6 8 100.0
0.2
0.4
0.6
0.8
1.0
Fluorescence-DetectionRayleigh-Zone
Separation (mm)
Eff
icie
ncy
Transport Efficiency of Single Atoms (1)
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Laser sequence
0 100 200 300 400 500 600 7000
100
200
300
400
500
600
700
fluor
esc
ence
[cou
nts
/100
ms]
time [ms]
MOTdipole trap
MOT
mut
ual
detu
ning
oneatom
+∆ω
-∆ω
forward
backward
motion of thestanding wave0
1 ms
Laser sequence
0 100 200 300 400 500 600 7000
100
200
300
400
500
600
700
fluor
esc
ence
[cou
nts
/100
ms]
time [ms]
MOTdipole trap
MOT
mut
ual
detu
ning
oneatom
+∆ω
-∆ω
forward
backward
motion of thestanding wave0
1 ms
Laser sequence
0 100 200 300 400 500 600 7000
100
200
300
400
500
600
700
fluor
esc
ence
[cou
nts
/100
ms]
time [ms]
MOTdipole trap
MOT
mut
ual
detu
ning
oneatom
+∆ω
-∆ω
forward
backward
motion of thestanding wave0
1 ms
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
distance [mm]
eff
icie
ncy
-4 -2 0 2 4 6 8 100.0
0.2
0.4
0.6
0.8
1.0
Fluorescent Detection
MOT-Recapture
Transport Efficiency of Single Atoms (2)
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
0
0.02
0.04
0.06
0.08
10 12 14 16 18 20z [mm]
U [m
K] ρ
Utot
Ueff
U (z)eff
U (z)
0
2. Deterministic Source of Cold Atoms
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
“Moving standing wave”
atom
1, 2, 3, ... Atoms0, 1, 2, ... Photons
Delivery of atomsON DEMAND !!
2. Deterministic Source of Cold Atoms
D. Frese, B. Ueberholz, S. Kuhr, W. Alt, D. Schrader, V. Gomer, and D. Meschede, Phys. Rev. Lett., 85 3777 (2000)S. Kuhr, W. Alt, D. Schrader, M. Müller,V. Gomer,D. Meschede, Science 293, p. 278-280, (2001)D. Schrader, S. Kuhr, W. Alt, M. Mueller, V. Gomer, D. Meschede, Appl Phys B 73 (2001) 8, 819-824
Refs:
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Experimenting with Single Neutral Atoms in a MOT
2. Deterministic Source ofSingle Neutral atoms
3. Single Atom Dynamics4. Towards entanglement
Overview
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3. Single Atom Dynamics
Spectroscopyof a single neutral atom
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Photon Bursts of Individual Trapped Atoms
Time [ms]
1 Atom
Phot
ons/
20m
s
Time [ms]
No Atom
Phot
ons/
20m
s
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Spectroscopy of atoms in dipole trap
0 20 40 60 80 1000
20
40
60
80
100F
luor
esce
nce
[cou
nts/
ms]
Probe laser detuning [MHz]
0,50 W1,05 W2,15 W
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
σ-polarisiert
π-polarisiert
0 20 40 60 80 1000.0
0.2
0.4
0.6
0 20 40 60 80 1000.0
0.2
0.4
0.6
Detuning [MHz]
Detuning [MHz]
Flu
ores
cenc
e[a
.u.]
Flu
ores
cenc
e[a
.u.]
0 20 40 60 80 1000
500
1000
0 20 40 60 80 1000
1000
2000
Detuning [MHz]
Detuning [MHz]
Pho
tons
Pho
tons
∆mF=0
∆mF=1
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
ground state
excited state
Optical dipole potential = AC Stark effect
3. Single Atom Dynamics
Bound excited states!
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3. Single Atom Dynamics
Acceleratinga single neutral atom
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
10 100 1000 10000 100000 10000000.0
0.2
0.4
0.6
0.8
1.0
a [m/s2]
Effi
zien
z
δν
tt / 20
vmax
3. Single Atom Dynamics
aspontaneous
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Axial oscillation frequencyExcitation mechanism
dipole traplaser
dipole traplaser
vacuumwindow
resonant excitation ifparametric excitation if
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
200 400 600 800 1000 1200 1400 1600 1800 2000 2200 24000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Model: GaussChi^2 = 1.23
frequency1 330 ±5 kHzwidth1 66 ±10 kHz
frequency2 660 ±15 kHzwidth2 112 ±24 kHzd
ete
ctio
ne
ffic
ien
cy
∆ω [kHz]
resonantexcitation
parametricexcitation
Frequency measurement
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
3. Single Atom Dynamics
„Temperature“ (E/kB)of a single neutral atom
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
UE
x0U1 E1=U1
x0
∫ == const.dxpSAdiabatic Cooling:
x
U0
E0
0
V(U,x)
3. Single Atom Dynamics
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
0.0 0.1 0.2 0.3 0.40.0
0.2
0.4
0.6
0.8
1.0
Initial energy of atom E0/U0
surv
ival
pro
babi
lity
p(E) ~ E2exp(-E/kT)
3. Single Atom Dynamics
T ~ TDoppler
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
1. Experimenting with Single Neutral Atoms in a MOT
2. Deterministic Source ofSingle Neutral atoms
3. Single Atom Dynamics4. Towards entanglement
Overview
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Creation of entangled and fully controlled atoms
( )12
4. Towards Entanglement
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Next technical implementation:Raman cooling to dipole trap ground state
0
T=E/kB
U(x)U0
x
4. Towards Entanglement
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
top view:
Nd:YAGlaser
MOT laserresonator
side view:
MOT laser Nd:YAGlaser
resonator200 µm
1 mm
4. Towards Entanglement
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Conclusion
We can or will control neutral atoms:
Atoms are excellent quantum memories ... Photons make good transmitters, switches ...
Exact number UUQuantum state (internal) UUPosition (global) UU
Trapping oscillator stateNumber of photons in cavity.....
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Copyright Research Group of Dieter Meschede, University of Bonn, Feb. 2002
Merci beaucoup pour votre attention !