1. Observation of Quantum Beating in Rubidium at 2. 1 THz and 18
Observation of Quantum Beating in Rubidium at 2.1 THz and 18.2 THz: Long-Range Rb*-Rb Interactions.
WILLIAM GOLDSHLAG, BRIAN J. RICCONI, J. GARY EDEN
Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering,
University of Illinois at Urbana-Champaign,
Urbana, IL, USA.

2. Overview
Quantum beating has been observed at frequencies up to 55 THz.
Interaction between 7s-5d and 8s-6d wave packets is observed.
A new tool for probing Rb*-Rb* interactions at long range ( Å).

3. Quantum Beat Spectroscopy

4. Excitation of Atomic Wave Packets in Rubidium
Spectrum of coherent excitation source 5d 7s
E:\ToBigSpore\Illinois\Research\QuantumBeating\Physical_Quantities_and_Conversions\Energy_levels\Rb_EnergyLevels_HighVisibility\Rb_2photon_excitations_and_relaxations_andPumpOverlap.png

5. Schematic Diagram of the Experimental Layout
55 fs Ti:Al2O3 laser
50/50 ΔT
dichroic
mirror
50/50
Oven
Quantum beating intensity
Delay
stage
Beam
profiler
Laser
pump
power

6. Quantum Beating in Time Domain
Strong182_quantumBeats-200C\02-01-TimeD4.png
Strong182_quantumBeats-200C\ TimeD-zoomX-coherentTransient2-4.png

7. Strong Quantum Beats in Time Domain
TimeD-zoomX-individualBeats_around5ps-datapoints-font16.png
QuantumBeating\Physical_Quantities_and_Conversions\Energy_levels\Rb_EnergyLevels_HighVisibility\Rb_quantum_beat_stateGroups-mainTwo.png
Energy levels of Rb
producing strongest
quantum beating

8. Spectral Intensity of 6p Emission to Ground (420 nm)
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-60THz-hiPass0d25THz-harmonicsAround_36.45THz-noLabels.png

9. Spectral Lines Attributed to Wave Packet Interactions
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-zoomY-peakAssignments-60THz-wProcesses-primaryLabels.png

10. Optical Process Generating the 18.225 THz Quantum Beating
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-zoomY-peakAssignments-60THz-wProcesses-18d2-2.png

11. Optical Process Generating the 2.107 THz Quantum Beating
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-zoomY-peakAssignments-60THz-wProcesses-2d1-2.png

12. Optical Process Generating the 10.73 THz Quantum Beating
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-zoomY-peakAssignments-60THz-wProcesses-10d73-2.png

13. Spectral Lines Attributed to Wave Packet Interactions
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-170C\ FrequencyD-60THz-hiPass0d25THz-peakAssignments.png

14. Perspective View of a Spectrogram

15. Perspective View of a Spectrogram

16. Temporal Behavior of Main Quantum Beating Lines
7s-5d
8s-6d
“5s-p-d”
Plots are not to scale.
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-200C\ spectralLinePowerDensityEvolution_18d2_vs_10d7-noLegend.png
Illinois\Research\QuantumBeating\Physical_Quantities_and_Conversions\Energy_levels\Rb_EnergyLevels_HighVisibility\Rb_quantum_beat_stateGroups-mainThree.png
Energy levels of Rb comprising the wave packets.
Time delay between pulses, ps.

17. Temporal Behavior of Main Quantum Beating Lines
Plots are not to scale.
7s-5d
Illinois\Research\QuantumBeating\ Strong182_quantumBeats-200C\ spectralLinePowerDensity_18d2_1st_vs_2nd_harmonics-noLegend.png
Illinois\Research\QuantumBeating\Physical_Quantities_and_Conversions\Energy_levels\Rb_EnergyLevels_HighVisibility\Rb_quantum_beat_stateGroups-harmonics_of_18d2.png
2x (7s-5d)
Energy levels of Rb comprising the wave packets.
Time delay between pulses, ps.

18. Summary
Observed quantum beating in rubidium at frequencies up to 55 THz using parametric four-wave mixing.
Multiple wave packets were simultaneously observed, and they appear to be trading energy.
The wave packets allow us to look into long-range interactions of rubidium atoms, making quantum beat spectroscopy a new tool for studying molecular interactions.