Quantum interference phenomenon in the cold atomic cascade

Quantum interference phenomenon in the cold atomic cascade system $$ : National Science Council and National Space Program Office, Taiwan Ray-Yuan Chang, Wei-Chia Fang, Ming-Da Tsai, and Chin-Chun Tsai National Cheng Kung University, Tainan, 70148 Taiwan

Classical analogy Young's interference

Quantum interference Fano interference Autler-Townes splitting

Transmission (arb. unit) Absorption (arb. unit) Quantum interference EIT

Energy level diagram Cesium F=4 Coupling laser Ti : Sapphire 794. 4 nm F=5 Probe laser 852 nm F=4 Calibration tool and marker for Rydberg state transition Transmission (arb. unit) 133 RTEIT Δc (MHz)

Cs MOT F’=5 4 3 2 MOT laser Repump laser F=4 3

Experimental Setup M M Cs vapor cell Red filter Probe Anti-Helmholtz Coil for MOT Chopper ND filter BS Cold Cs Atom M BS PD Coupling Probe f PD 1 AOM Repump Laser MOT Laser Ti: Sapphire laser

Trap Loss F=5 Probe laser 852 nm F=4 f PD

Suppression F=5 Probe laser 852 nm F=4

Suppression F=4 Coupling laser Ti : Sapphire F=5 Probe laser F=4 Recovery

Suppress Recover Loading Interaction MOT LASER F=4 Ti-Sa LASER Probe LASER Repump LASER AH Coil Ti-Sa LASER Step suppress recover Coupling laser Ti : Sapphire F=5 Probe laser F=4

Chop Mode Loading Interaction MOT LASER Ti-Sa LASER Probe LASER Repump LASER AH Coil Ti-Sa LASER Step suppress recover

Suppress Recover Coupling 30 m. W Probe off F=4 Coupling laser Ti : Sapphire Probe on F=5 Probe laser RT EIT F=4

Power dependence Probe 5μW Coupling 10 m. W F=4 3 m. W 0. 8 m. W Coupling laser Ti : Sapphire F=5 0. 4 m. W 0. 2 m. W 0. 15 m. W Probe laser F=4

Power dependence ~3. 5 MHz

Power dependence Laser linewidth 0. 5 MHz Laser linewidth 0 MHz

Conclusion

Absorption EIT/CPT Enhanced

EIT features Δp=0 Coupling 8. 3 m. W 150μW Δp varies Δp= -53 MHz -23 MHz 15. 6 m. W +26 MHz 38. 9 m. W +70 MHz

Periodical Table Rb Xe Ba Fr I am Here!!!

Importance NIST-F 1 Frequency standard (9. 2 GHz) -16 ~ 6 × 10 , June 2004).

Scattering Force Atom Photon Atom Spontaneous emission in a random direction Ultracold Lab.

Doppler Cooling Hansch and Schawlow Opt. Commun. 13, 68 (1975) Damp force Ultracold Lab.

Magneto-Optical Trap Steven Chu and D. E. Pritchard Phys. Rev. Lett. 59, 2631 (1987) mj |e> J=1 -1 +1 0 0 +1 -1 0 |g> J=0 B<0 B=0 B>0 Ultracold Lab.

Ultracold Atomic Physics Lab. Ray-Yuan Chang Chin-Chun Tsai

My PHD career 1. Wavemeter Δλ/λ～ 10 -7 < 50 MHz

My PHD career 2. Na 2 OODR spectroscopy 3 p+3 p New observation 3 s+4 p Extend to the higher rovibrational levels 3 s+4 d Avoid crossing 3 s+4 f 3 s+5 d L-uncoupling and Λ doubling 3 s+4 d 3 s+5 p Extend to the higher rovibrational levels

My PHD career 3. Precision measurement of the Rydberg states Dye Laser : 560 nm~630 nm Dn ~ 10 MHz

Schematic of EIT Ωc >> Ωp Δc = 0 Δp～

Our system Phys. Rev. A 59 , 4675 (1999)

Dressed state approach Claude Cohen-Tannoudji D D

Autler-Townes splitting CPT EIT

Pathway Cancellation

Direct excitation Trap Loss ØLoading ØPower broadening EIT △c MHz

Time sequence

Time sequence F=4 Loading Interaction MOT LASER Coupling laser Ti : Sapphire Repump LASER F=5 4 3 2 Ti-Sa LASER Step MOT laser Ti-Sa LASER Repump laser AH Coil F=4 3

Aulter-Townes splitting MOT fluorescence F’’=4 Coupling laser Ti : Sapphire 4 3 2 MOT laser RT EIT Repump laser F’=5 F=4 3

EIT process in MOT F=4 133 Coupling laser Ti : Sapphire 4 3 2 MOT laser Repump laser F=5 Probe laser F=4 3 Cesium

Time sequence Loading Interaction MOT LASER Repump LASER AH Coil Ti-Sa LASER Probe LASER Ti-Sa LASER Step F=4 Coupling laser Ti : Sapphire 794. 5 nm F=5 Probe laser 852 nm F=4

EIT in MOT EIT F=4 Coupling laser Ti : Sapphire F=5 Probe laser MOT fluorescence F=4

Room temperature EIT Two extreme of probe intensity

) Hz (M Δc ( MH z) ) Hz (M Ωp Transmission (arb. unit) EIT&Raman absorption Transmission (arb. unit) Ωp Δc ( MH z)

Autler-Townes splitting CPT EIT

Doubly dressed states

Doubly dressed

Doubly dressed Splitting of EIT doublet

Absorption EIT/CPT Enhanced

Energy level diagram F=4 133 Coupling laser Ti : Sapphire 794. 4 nm F=5 Probe laser 852 nm F=4 Cesium

Decay fluorescence 8 s 7 s 6 p 6 s Fluorescence intensity 7 p

Excitation F’’=4 Coupling laser Ti : Sapphire 4 3 2 MOT laser Repump laser F’=5 F=4 3

Equation of motion

Schematic of EIT

Coupled differential equation Steady state

Our system Phys. Rev. A 59 , 4675 (1999)

Scan coupling Background Free

Decay fluorescence 7 p to 6 s 8 s 7 p 7 s 6 p 6 s

Experimental Setup M Cs vapor cell PD 1 Chopper Red filter M BS AOM AOM MOT Laser Ti: Sapphire laser

Simulation Calibration tool and marker for Rydberg state transition