Laser induced manipulation of atom pair interaction

Transcription

1 Laser induced manipulation of atom pair interaction St. Falke, Chr. Samuelis, H. Knöckel, and E. Tiemann Institute of Quantum Optics, European Research Training Network Cold Molecules SFB 407 Quantum limited measuring processes with atoms, molecules and photons supported by DFG

2 Tuning the scattering cold and ultra cold ensembles interaction energy atom-light collision energy variation of scattering properties significant within light fields tuning scattering length Fedichev et al, Phys.Rev.Lett. 77, 913 (1996) observation in photo association spectra Fatemi et al, Phys.Rev.Lett. 85, 446 (000) observation in Rb BEC Theis et al, Phys.Rev.Lett. 93, (004) Poster 15 by Johannes Denschlag Talk by Vladimir Melezhik on anisotropic effects Tue, 16:30

3 5000 v = s+3p energy [cm -1 ] L v =15 fluorescence 1 Σ + u L3 fluorescence Spectroscopy of cold collision regime v X =0 L1 1 X Σ 3 a Σ v =9 X g + + u internuclear distance [ Å] L1 3s+3s Stokes laser L3 pump laser L example Na + Na molecular beam fluorescence fluorescence

4 Spectroscopy of cold collisions 1.0 shape resonance Feshbach resonance threshold v X=65 l=0 f= 1+1 v X =65 l= f=0, l=0 f= l= f= 1+ + asymptote energy in cm -1 detection by fluorescence from v =139 J =1 R out Å

5 Stimulating to the continuum from different excited states v = outer turning point shifts with v ernergy test of the scattering function in this region v x =9 v x = 65 v a =14,15 and continuum internuclear separation R

6 Spectroscopy of coupled molecular systems

7 symptotic coupling by light cm Π g ~ R -5 3s+3d Σ + g v ~180 manipulation laser (chopped) ~ R Σ + u 3s+3p scanning laser v X =31 fluorescence (signal) X 1 Σ + g ~ R -6 3s+3s R [Å]

8 Levels at asymptote 3s+3p coupled to 3s+3d fluorescence P6/R coupling laser 40.3 W / cm 75 MHz blue to atomic 3p - 3d transition 1/ 3/ v = v = dressed state asymptote MHz

9 asymptotes in dressed picture energy δω δω δω v =180 v =180 1 Σ + u 4 1 Σ + g 4 1 Σ + g 4 1 Σ + g and 1 Π g and 1 Π g and 1 Π g 3s +3d 1/ 3/ 3s +3p 1/ 1/ 3s +3d 1/ 3/ 3s +3d 1/ 3/ internuclear separation R

10 Detuning of the coupling laser band (v v X ) = (178-9) δω = -571 MHz δω = MHz J =5 J = δω = -771 MHz MHz δω = +79MHz 3s 1/ +3d 3/ blue detuned coupling laser 74 W / cm predissociating δω

11 Coupling matrix for selected Σ Σ Π Π Π J=7 J=6 J=8 J=6 J=7 J=8 R and J s P R Σ Σ J=7 J=6 J=8 T+ V Ω Ω Ω T+ V+ P Ω T+ V+ P Ω Ω Ω T kinetic energy P Q Π Π J=6 J=7 Ω Ω T+ V+ P T+ V+ P V potential energy R P optical potential Π J=8 Ω T+ V+ P Ω Rabi frequency neglected: fine structure hyperfine interaction spontaneous emission

12 Potential barriers of the coupled states

13 Full matrix with kinetic energy R 1 R R 3 R n

14 Profile simulations no coupling with coupling J =5 J =7 J =5 J =7 v =181 v =181 fluorescence fluorescence I=0 I= I=0 I= MHz MHz fit yields the profile parameters 40.3 W/cm ω L - Ε(3d 3/ -3p 1/ ) = +75 MHz blue detuned fit yields light shift and broadening

15 Comparison of observations and simulations shift in MHz broadening in MHz experiment (fit) simulation v = 179 J =7 75 W/cm experiment simulation (good fit) (bad fit) v = 179 J =7 MHz 75 W/cm shift in MHz broadening in MHz v = 179 J =7-40 experiment (fit) -45 simulation W/cm v = 179 J =7 experiment (fit) MHz detuning MHz detuning asymptote 3s 1/ (f=1) +3d 5/ detuning in MHz W/cm

16 Manifold at the 3s+3d asymptote of Na 0.1 S f=+ D 3/ S f=+ D 5/ 0.0 S f=1+ D 3/ -0.1 S f=1+ D 5/ E (cm -1 ) Na 3s+3d asymptote R (bohr)

17 Curve crossing for more predissociation

18 Coupling to the ground state asymptote -1 V [cm ] 1 + u scanning fixed laser laser scanning laser laser for coupling 1 + g

19 Power and frequency dependence of manipulation fluorescence in a.u L3 on resonance 56mW L3 150 MHz red detuned L3: 16.5 mw detuning L in MHz detuning L L in in MHz coupling X 1 Σ + g v=64 l=0, f= and 1 Σ + u v=10, J=0

20 Scattering model LIF open prepared molecule open interaction with laser fields unaffected molecule open + closed dissociated pair of atoms open Bohn, Julienne, Phys.Rev.60, 414 (1999)

21 Reaction matrix K o o K o c K c o K c c energy normalized equal footing for open and closed channel functions v X =9 v X =9 LIF dissociation v =139 v X =65 v =139 LIF d iss. v =139 LIF v X =65 dissociation v X =65 v X =9 Bohn, Julienne, Phys.Rev.60, 414 (1999)

22 Coupling scheme with linear polarized light F 1 I=0 M=0 J=1 3 1 I= M=0 J=1 F l= l=0 0 l= l= J=0 J=0 I= M =1 I= M = 3 1 J=1 3 J=1 l= l= l= l=0 4 3 J=0 J=0

23 Simulation and hyperfine composition v =10 J =1 537 W/cm δω := 0 MHz with coupling to v X =64 l=0 composition by hyperfine components I = 0 I = M = M = 1 M = 0 without coupling simulated spectrum MHz MHz 1000

24 simulation with detunings v =10 J =1 v =10 J =1 537 W/cm δω = -16 MHz fit result: δω = -131MHz 497 W/cm δω = 10 MHz fit result: δω = 16MHz with coupling to v X =64 l=0 without coupling with coupling to v X =64 l=0 without coupling MHz MHz coupling of closest bound level below the asymptote -90 MHz v =139 J =1 610 W/cm with coupling to v X =65 l=0 least bound level without coupling MHz 1000

25 Conclusions Scattering spectroscopy gives detailed insight and resonance profiles Long range manipulation Observation of bound and dissociating levels Quantitative description with multi channel model Dissociation broadening not described Resonance coupling of ground state levels Observation of complex profiles Scattering model including hyperfine interaction Overall agreement satisfactory Decomposition in nuclear spin components Relative magnitudes wrong? Stationary solutions only Competition transit time and Rabi cycle time