Presentation on theme: "Simon Hutchinson February 21 st 2012. What did they accomplish? “full electromagnetic transparency to XUV light in He can be achieved by destructively."— Presentation transcript:
Simon Hutchinson February 21 st 2012
What did they accomplish? “full electromagnetic transparency to XUV light in He can be achieved by destructively interfering two distinct multi-photon ionization pathways” 1.Electromagnetic transparency via quantum interference 2. Multi-photon ionization pathway – XUV + IR Helium Ip = 24.6 eV XUV IR 3. Results: Transparency and modulation of ionisation rate at twice the electromagnetic frequency of the IR pulse.
|1› |2› |3› Dressing field 1.Opposite phase 2.Same amplitude Creates coherent states and allows for quantum interference Electromagnetically Induced Transparency IMPORTANT FOR LATER
Assisted Ionisation Channels in Helium eV 1s Continuum eV2p Dressing Field eV eV Photon Energy Resultant Excitation 11 th Harmonic to eV to eV 13 th Harmonic to eV to eV 1. Coherence 2. Coupling 1. 2.
Control in the Experiment 1. XUV amplitude -XUV mirror coatings -Al filter (Total Ionization Channel Probability Amplitude) 2. XUV energy tuning -Phase-matching via pressure tuning
Control in the Experiment 3. Phases of interfering channels -Delay between IR dressing field and XUV pulses
The Experiment (part one) Using COLTRIMS, measure He + yield as the 13 th harmonic is scanned. (XUV at t0, IR x-axis) Enhancement for positive delays: transient (resonant?) multi-photon ionisation.
The Experiment (part two) Lifetime of 2p state in helium = 10ps Phys. Rev. A 28, 3340–3348 (1983)