Download presentation
Presentation is loading. Please wait.
Published byShawn Caldwell Modified over 9 years ago
1
Transient enhancement of the nonlinear atom-photon coupling via recoil-induced resonances: Joel A. Greenberg and Daniel. J. Gauthier Duke University 5/22/2009 Cavity-less Rayleigh Superfluorescence in a Thermal Gas FIP
2
Superfluorescence (SF) L Pump Dicke, Phys. Rev. 93, 99 (1954); Bonifacio & Lugiato, Phys. Rev. A 11, 1507 (1975), Polder et al., Phys. Rev. A 19, 1192 (1979), Rehler & Eberly, Phys. Rev A 3, 1735 (1971) W N ‘endfire’ modes W 2 /L
3
SF Threshold time Power SF sp /N sp Cooperative emission produces short, intense pulse of light P peak N 2 Delay time ( D ) before pulse occurs Threshold density/ pump power DD P peak 1 Spontaneous Emission Amplified Spontaneous Emission (ASE) Superfluorescence (SF) SF Thresh Cooperativity Malcuit, M., PhD Dissertation (1987); Svelto, Principles of Lasers, Plenum (1982)
4
New Regime: Thermal Free-space SF Pump (F) Cold atoms Pump (B) Detector (B) Detector (F) - T=20 K - L=3 cm, R=150 m - N~10 9 Rb atoms - P F/B ~4 mW - F2 F’3 =5 F =R 2 / L~1 NO CAVITY! NOT BEC! ≠ Slama et al. ≠ Inouye et al. Inouye et al. Science 285, 571 (1999); Slama et al. PRL 98, 053603 (2007) * Counterpropagating, * Large gain path length 2 collinear pump beams 1 1) Wang et al. PRA 72, 043804; 2) Yoshikawa PRL 94, 083602
5
Results - SF t ( s) Power ( W ) Forward Backward F/B Pumps MOT beams Light persists until N falls below threshold F/B temporal correlations ~1 photon/atom large fraction of atoms participate on off Wang et al. PRA 72, 043804 (2005)
6
DD time Power P peak P F/B (mW) P peak ( W) D ( s) P F/B (mW) Density/Pump power thresholds P peak P F/B D (P F/B ) -1/2 Results - SF Consistent with CARL superradiance * *Piovella et al. Opt. Comm. 187, 165 (2001)
7
SF Mechanism What is the mechanism responsible for SF?
8
Probe Pump (F) Cold atoms Pump (B) Detector (B) - T=20 K - L=3 cm, R=150 m - N~10 9 Rb atoms - P F/B ~4 mW - F2 F’3 =5 Detector (F) ( p = + ) What is the mechanism responsible for SF? SF Mechanism
9
Probe Spectroscopy Forward Detector Backward Detector (FWM) (kHz) Rayleigh SF signal time ( s) Probe Power Rayleigh pump beam alignment Raman pump beam alignment SF Power Raman SF
10
Probe Spectroscopy Forward Detector Backward Detector (FWM) (kHz) Rayleigh SF signal time ( s) Probe Power Rayleigh pump beam alignment Raman pump beam alignment SF Power Raman SF Rayleigh scattering is critical for observation of SF
11
Observe free-space superfluorescence in a cold, thermal gas Large F/B gain path length + pair of pump beams Spectroscopy and beatnote imply Rayleigh scattering as source of SF Temporal correlation between forward/backward radiationConclusions
12
Study dependence of P peak and D on N Look at competition between vibrational Raman and Rayleigh SF Future Work
13
Beatnote (kHz) Look at beatnote between probe beam and SF light as probe frequency is scanned Power (F)
14
Beatnote (kHz) time ( s) 1/ f f~450kHz f SF ~-50kHz Look at beatnote between probe beam and SF light as probe frequency is scanned
15
Weak probe Forward: Rayleigh backscatteringBackward: Recoil-mediated FWM (kHz) Probe ( p = + ) Pumps ( ) I out /I in Forward Backward Rayleigh
16
Weak probe Probe ( p = + ) Pumps ( ) Forward Backward FWM Above Thresh Below thresh (kHz)
17
Weak probe Probe ( p = + ) Pumps ( ) Forward Backward Forward (kHz)
18
Coherence Time time Power F/B Pumps on off off 1 PRPR PRPR
19
Lin || Lin Power time ( s) Pumps ( ) Forward Backward
20
DD time Power P peak P peak ( W) Results - SF *Piovella et al. Opt. Comm. 187, 165 (2001) OD N
21
CARL Regimes Slama Dissertation (2007) Quantum CARL Ultracold Atoms/BEC Good Cavity: < r Bad Cavity: > r Quantum: r >G Semiclassical: r <G In resonator Free space MIT (2003) MIT (1999) Tub (2006) Tub (2003) Tub (2006) Thermal
22
Conclusions Rayleigh backscattering Recoil-mediated FWM (kHz)
23
Superfluorescence (SF) L,N Pump Power SF sp /N sp DD P peak Cooperative emission produces short, intense pulse of light Emission occurs along ‘endfire’ modes P peak N 2
24
Superfluorescence (SF) L,N Pump gL 1 Spontaneous Emission Amplified Spontaneous Emission (ASE) Superfluorescence (SF) SF Thresh
25
Weak probe Forward: Rayleigh backscatteringBackward: Recoil-mediated FWM (kHz) Probe ( p = + ) Pumps ( ) I out /I in Forward Backward Rayleigh
26
Probe Spectroscopy Forward DetectorBackward Detector (FWM) (kHz) Rayleigh SF signal time ( s) Probe Power Rayleigh pump beam alignment Raman pump beam alignment SF Power Raman SF
27
Forward DetectorBackward Detector (FWM) Probe Spectroscopy (kHz) Rayleigh SF signal time ( s) Probe Power Rayleigh pump beam alignment Raman pump beam alignment SF Power Rayleigh scattering is critical for observation of SF
28
Observation of Cavity-less Rayleigh Superfluorescence in a Thermal Gas Joel A. Greenberg and Daniel. J. Gauthier Duke University 5/22/2009
29
Our Setup Pump (F) Cold atoms Pump (B) Detector (B) Detector (F) - T=20 K - L=3 cm, R=150 m - N~10 9 Rb atoms - P F/B ~4 mW - F2 F’3 =5 - No cavity - Thermal atoms - Counterprop. pumps Inouye et al. Science 285, 571 (1999); Slama et al. PRL 98, 053603 (2007)
30
Motivation Collective effects Self-organization Experimental results Conclusions/Future workOutline
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.