Nonlinear Spectroscopy of Cold, Trapped Atoms: Atomic Recoil and Localization Effects in a MOT T. M. Brzozowski M. M¹czyñska M. Zawada J. Zachorowski and W. Gawlik Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland Experimental setup Simplistic predictions | e,N-1> |e,N> | g,N> | g,N+1> | 2(N-1)> | 1(N-1)> | 2(N)> |1(N)> d d W’ w+W’ w+W’ w-W’ w-W’ w w w W’ The simplest model: dressed two level atom resonances @ , , w - W’ w w + W’ @ absorption ~ Im ( r ) eg 2 four wave mixing ~ |r | eg Different shapes of the absorption and FWM spectra, but resonances occur at the same frequencies! Experimental results absorption [arbitrary units] -4 -3 -2 -1 0 1 2 3 4 I/I =4.6 0 I/I =10.4 0 I/I =23.6 0 D (0,±1) D (0,±1) D (±1,±2) a b c probe - pump detuning [MHz] detuning of the trapping beams d=14 MHz Changes in absorption with trapping beam intensity D [MHz] w 0 - trapping beam frequency w 0 absorption four-wave mixing -60 -40 -20 0 20 w 0 Wide scan spectra Narrowed scan spectra: central structure s+ s- lin -2 -1 0 1 2 3 -2 -1 0 1 2 3 -2 -1 0 1 2 3 s+ s- lin absorption four-wave mixing pump - probe detuning [MHz] (s+/-, lin - polarization of the probe beam) Conclusions J. Zachorowski, T. M. Brzozowski, T. Pa³asz, M. Zawada, and W. Gawlik, Acta Phys. Polonica A 101, 61 (2002) trap beam frequency absorption four-wave mixing frequency Requirements Spectroscopy of cold atoms in the magneto-optical trap Experiment principle Investigation of atom energy levels perturbed by light Investigation of localization of atoms in the light field Investigation of atom dynamics in the trap Motivation absorption detection absorption detection four-wave mixing signal detection four-wave mixing signal detection trapping & pump beams trapping & pump beams probe beam probe beam Simultaneous detection of absorption and four-wave mixing (FWM) and locked master oscillator probe laser trapping laser double-pass AOM double-pass AOM frequency offset probe tuning single-pass AOM single-pass AOM frequency offset frequency offset trapping beam probe beam injection injection High spectroscopic resolution Laser stabilization and tuning precision up to single kHz D - detuning from atomic resonance F=3 - F’=4 s+ s- frequency reference & stabilization Enhanced resolution spectra absorption four-wave mixing pump - probe detuning [MHz] (s+/- - polarization of the probe beam) Raman transitions between the vibrational levels in optical lattices Transitions between the states in continuum: Recoil induced resonances absorption four-wave mixing Mechanisms responsible for central structure Raman transitions between light shifted Zeeman sublevels absorption four-wave mixing 2 D (±1,±2) [kHz] 2 D (0,±1) [kHz] The plot of D vs. D (0,±1) (±1,±2) 2 3, 1 3, 0 3, 7 3 7 2 7 15 2 1 D (0,±1) D (±1,±2) -1 3, -2 3, D (±1,±2) 7 3 7 15 2 1 Light-shifted Zeeman sublevels 85 of F=3 level of Rb atom 500 600 700 800 900 1000 1100 1200 1000 1500 2000 2500 3000 3500 a b Fitting: y = a + b x = -392.1 ± 65.3 = 3.16 ± 0.08 slope: 3.0 weak intensity pól 2 (~W / d) slope: 3.22 strong intensity limit (~W) Trapping beams detunung d = 14 MHz D (0,±1) D (±1,±2) a b c D (0,±1) Interpretation -2 -1 0 1 2 -2 -1 0 1 2 four-wave mixing absorption Our spectra probe the dynamics of trapped atoms. results from transitions between: Central structure Light-perturbed Zeeman subleveles Vibrational levels in optical lattice Kinetic continuum states Four-wave mixing signals reveal more details but require explanation of: differences between resonances in the absorption and FWM spectra dynamic effects: signal dependence on scan speed and direction signal dependence on the probe polarization References pump photon (from trapping beam) probe photon
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Nonlinear Spectroscopy of Cold, Trapped Atoms: Atomic Recoil and Localization Effects in a MOT
T. M. Brzozowski M. M¹czyñska M. Zawada J. Zachorowski and W. Gawlik
Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland
Experimental setup Simplistic predictions
| e,N-1>
|e,N>
| g,N>
| g,N+1>
| 2(N-1)>
| 1(N-1)>
| 2(N)>
|1(N)>
d
d
W’
w+
W’
w+
W’
w-
W’
w-
W’
w
wwww
W’
The simplest model: dressed two level atom
resonances @ , , w - W’ w w + W’@
absorption ~ Im ( r )eg
2four wave mixing ~ |r |eg
Different shapes of the absorption and FWM spectra, but resonances occur at the same frequencies!
Experimental results
ab
sorp
tion
[a
rbitr
ary
un
its]
-4 -3 -2 -1 0 1 2 3 4
I/I =4.60
I/I =10.40
I/I =23.60
D (0,±1) D (0,±1)
D (±1,±2)
a
b
c
probe - pump detuning [MHz]
detuning of the trapping beams d=14 MHz
Changes in absorptionwith trapping beam intensity
D [MHz]
w0 - trapping beam frequency
w0
absorption
four-wave mixing
-60 -40 -20 0 20
w0
Wide scan spectra Narrowed scan spectra: central structure
s+ s-lin
-2 -1 0 1 2 3 -2 -1 0 1 2 3 -2 -1 0 1 2 3
s+ s-lin
absorption
four-wave mixing
pump - probe detuning [MHz]
(s+/-, lin - polarization of the probe beam)
Conclusions
J. Zachorowski, T. M. Brzozowski, T. Pa³asz, M. Zawada, and W. Gawlik, Acta Phys. Polonica A 101, 61 (2002)
trap beam frequency
absorption
four-wave mixing
frequencyRequirements
Spectroscopy of cold atomsin the magneto-optical trap
Experiment principle
Investigation of atom energy levels perturbed by light
Investigation of localization of atoms in the light field
Investigation of atom dynamics in the trap
Motivation
Nonlinear Spectroscopy of Cold, Trapped Atoms: Atomic Recoil and Localization Effects in a MOT
T. M. Brzozowski M. M¹czyñska M. Zawada J. Zachorowski and W. Gawlik
Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland
Experimental setup Simplistic predictions
| e,N-1>
|e,N>
| g,N>
| g,N+1>
| 2(N-1)>
| 1(N-1)>
| 2(N)>
|1(N)>
d
d
W’
w+
W’
w+
W’
w-
W’
w-
W’
w
wwww
W’
The simplest model: dressed two level atom
resonances @ , , w - W’ w w + W’@
absorption ~ Im ( r )eg
2four wave mixing ~ |r |eg
Different shapes of the absorption and FWM spectra, but resonances occur at the same frequencies!
Experimental results
ab
sorp
tion
[a
rbitr
ary
un
its]
-4 -3 -2 -1 0 1 2 3 4
I/I =4.60
I/I =10.40
I/I =23.60
D (0,±1) D (0,±1)
D (±1,±2)
a
b
c
probe - pump detuning [MHz]
detuning of the trapping beams d=14 MHz
Changes in absorptionwith trapping beam intensity
D [MHz]
w0 - trapping beam frequency
w0
absorption
four-wave mixing
-60 -40 -20 0 20
w0
Wide scan spectra Narrowed scan spectra: central structure
s+ s-lin
-2 -1 0 1 2 3 -2 -1 0 1 2 3 -2 -1 0 1 2 3
s+ s-lin
absorption
four-wave mixing
pump - probe detuning [MHz]
(s+/-, lin - polarization of the probe beam)
Conclusions
J. Zachorowski, T. M. Brzozowski, T. Pa³asz, M. Zawada, and W. Gawlik, Acta Phys. Polonica A 101, 61 (2002)
trap beam frequency
absorption
four-wave mixing
frequencyRequirements
Spectroscopy of cold atomsin the magneto-optical trap
Experiment principle
Investigation of atom energy levels perturbed by light
Investigation of localization of atoms in the light field
Investigation of atom dynamics in the trap
Motivation
Nonlinear Spectroscopy of Cold, Trapped Atoms: Atomic Recoil and Localization Effects in a MOT
T. M. Brzozowski M. M¹czyñska M. Zawada J. Zachorowski and W. Gawlik
Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland
Experimental setup Simplistic predictions
| e,N-1>
|e,N>
| g,N>
| g,N+1>
| 2(N-1)>
| 1(N-1)>
| 2(N)>
|1(N)>
d
d
W’
w+
W’
w+
W’
w-
W’
w-
W’
w
wwww
W’
The simplest model: dressed two level atom
resonances @ , , w - W’ w w + W’@
absorption ~ Im ( r )eg
2four wave mixing ~ |r |eg
Different shapes of the absorption and FWM spectra, but resonances occur at the same frequencies!
Experimental results
ab
sorp
tion
[a
rbitr
ary
un
its]
-4 -3 -2 -1 0 1 2 3 4
I/I =4.60
I/I =10.40
I/I =23.60
D (0,±1) D (0,±1)
D (±1,±2)
a
b
c
probe - pump detuning [MHz]
detuning of the trapping beams d=14 MHz
Changes in absorptionwith trapping beam intensity
D [MHz]
w0 - trapping beam frequency
w0
absorption
four-wave mixing
-60 -40 -20 0 20
w0
Wide scan spectra Narrowed scan spectra: central structure
s+ s-lin
-2 -1 0 1 2 3 -2 -1 0 1 2 3 -2 -1 0 1 2 3
s+ s-lin
absorption
four-wave mixing
pump - probe detuning [MHz]
(s+/-, lin - polarization of the probe beam)
Conclusions
J. Zachorowski, T. M. Brzozowski, T. Pa³asz, M. Zawada, and W. Gawlik, Acta Phys. Polonica A 101, 61 (2002)
trap beam frequency
absorption
four-wave mixing
frequencyRequirements
Spectroscopy of cold atomsin the magneto-optical trap
Experiment principle
Investigation of atom energy levels perturbed by light
Investigation of localization of atoms in the light field
Investigation of atom dynamics in the trap
Motivation
Nonlinear Spectroscopy of Cold, Trapped Atoms: Atomic Recoil and Localization Effects in a MOT
T. M. Brzozowski M. M¹czyñska M. Zawada J. Zachorowski and W. Gawlik
Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland
Experimental setup Simplistic predictions
| e,N-1>
|e,N>
| g,N>
| g,N+1>
| 2(N-1)>
| 1(N-1)>
| 2(N)>
|1(N)>
d
d
W’
w+
W’
w+
W’
w-
W’
w-
W’
w
wwww
W’
The simplest model: dressed two level atom
resonances @ , , w - W’ w w + W’@
absorption ~ Im ( r )eg
2four wave mixing ~ |r |eg
Different shapes of the absorption and FWM spectra, but resonances occur at the same frequencies!
Experimental results
ab
sorp
tion
[a
rbitr
ary
un
its]
-4 -3 -2 -1 0 1 2 3 4
I/I =4.60
I/I =10.40
I/I =23.60
D (0,±1) D (0,±1)
D (±1,±2)
a
b
c
probe - pump detuning [MHz]
detuning of the trapping beams d=14 MHz
Changes in absorptionwith trapping beam intensity
D [MHz]
w0 - trapping beam frequency
w0
absorption
four-wave mixing
-60 -40 -20 0 20
w0
Wide scan spectra Narrowed scan spectra: central structure
s+ s-lin
-2 -1 0 1 2 3 -2 -1 0 1 2 3 -2 -1 0 1 2 3
s+ s-lin
absorption
four-wave mixing
pump - probe detuning [MHz]
(s+/-, lin - polarization of the probe beam)
Conclusions
J. Zachorowski, T. M. Brzozowski, T. Pa³asz, M. Zawada, and W. Gawlik, Acta Phys. Polonica A 101, 61 (2002)
trap beam frequency
absorption
four-wave mixing
frequencyRequirements
Spectroscopy of cold atomsin the magneto-optical trap
Experiment principle
Investigation of atom energy levels perturbed by light
Investigation of localization of atoms in the light field
Investigation of atom dynamics in the trap
Motivation
absorptiondetectionabsorptiondetection
four-wave mixingsignal detection
four-wave mixingsignal detection
trapping & pump beamstrapping & pump beams
probe beamprobe beam
Simultaneous detection of absorptionand four-wave mixing (FWM) and
lockedmaster
oscillator
probelaser
trappinglaser
double-passAOM
double-passAOM
frequency offset
probe tuning
single-passAOM
single-passAOM
frequency offset
frequency offset
trapping beam
probe beam
injection
injection
High spectroscopic resolution
Laser stabilization and tuning precision up to single kHz
D - detuning from atomic resonance F=3 - F’=4
s+ s-
frequency reference &stabilization
Enhanced resolution spectraabsorption
four-wave mixing
pump - probe detuning [MHz]
(s+/- - polarization of the probe beam)
Raman transitionsbetween the vibrational levels in optical lattices
Transitions between the states in continuum:Recoil induced resonances