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Simplest interrogation scheme for the two-photons transition

Simplest interrogation scheme for the two-photons transition. Two-photons Ramsey spectroscopy. Raby frequency: E: electric field strength; R i,j : i  j transition probability; dw : laser detuning; P : power in W; w : waist radius in m To have a π/2 pulse:

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Simplest interrogation scheme for the two-photons transition

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  1. Simplest interrogation scheme for the two-photons transition

  2. Two-photons Ramsey spectroscopy • Raby frequency: • E: electric field strength; Ri,j: ij transition probability; • dw: laser detuning; P: power in W; w: waist radius in m • To have a π/2 pulse: • t: interaction time; v: atomic velocity in m/s • This is possible with v = 20 m/s and P = 50 W (laser power: 0.5 W, cavity enhancement factor: 100) using a waist radius of 0.5 mm

  3. Measurement of the one-photon transition probability • The transition rate Aki for the intercombination line @ 657.3 nm is well known (2900 s-1) • Simultaneous measurement of the integrated absorption coefficient a(n) @ 457.5 nm and 657.3 nm • Cell transmission: • L: length of the absorbing vapor; N: atomic density; • g(n): normalized lineshape; gi: level degeneracy

  4. Apparatus for measuring the E2 transition rate • Ti:Sa laser: 400 mW CW @ 915 nm • SHG with a KNbO3 crystal: 300 mW @ 457.5 nm • ECDL: 10 mW CW @ 657.3 nm • Frequency calibration: two Fabry-Pérot resonators • FSR 300 MHz • Absorption cell • length 0.6 m; diameter 2.5 cm; temperature 650÷700 °C

  5. Data analysis • Fit assuming a pure Doppler line broadening • Doppler linewidth ≈ 2 GHz • buffer gas (Ar) pressure: 10÷20 Pa • broadening coefficient ≈ 100÷150 kHz/Pa • Isotopic structure • most abundant isotopes: 40Ca (96.9%), 44Ca (2%), 42Ca (0.6%) • G(n) normalized Gaussian function

  6. Experimental apparatusfor measuring the E2transition rate

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