Fichas
Quantum optics-Set 1
Fichas del conjunto (15)
- 1π and π/2-Puls- π/2-Puls magtransfer superpos state into excited state
- mixture will be not completely transferred
- Rabifreq:
π/ R0: the whole population in excited state
π/2 R0: equal superposition - 2Fluorescence and natural linewidth- natural: γ10=FWHM at atomic transition
- fluorescence: fast decay - 3Absorption imaging of ultracold Atoms- lens=imaging system
- Bild des Schattens der Atome
- Off resonant laser - 4Suitable Atoms for laser cooling(Alkali and Alkaline Earths)- almost closed two-level transition
- availability of tonable narrow-bandlasers
- vapour pressure of the atomic gas in the range of mbar(102Pa) at reachable T (<1500°C)
- Alkali Atoms: n2S1/2 → n2P3/2 transition
- all isotopes posses spin (n2P1/2)[hyperfine structure] F=I-1/2; F=I+1/2
- Alkaline: 2 electrons in s-state n1S0 → n1P1 transition - 5Dipole selection rules- s‘=s
- L‘=L±1
- J‘=J; J±1
- F‘=F; F±1
- mF‘=mF; mF ±1 - 6Polarisation- ε0: describes linearly polarized light (mF‘=mF;π transition; quantization axis parallel to polarisation)
- ε+1: describes circularly polarized light (mF‘=mF+1;σ+ transition; quantization axis parallel to direction of propagation)
- ε-1: describes circularly polarized light (mF‘=mF-1;σ- transition; quantization axis parallel to direction of propagation) - 7Principle of slowing atomsmomentum transfer due to absorption
undirectional emission (spontaneous emission)
slowing force: (formula) - 8Doppler effect- due to doppler effect, the effective detuning depends on atom velocity
- adjust such that δeff=0
- solutions:
white laser(all frequencies)
adjust laser freq. (only pulsed possible)
transition freq. adjust → Zeeman slower - 9Zeeman slowerAbsorption Laserlicht und folgende Reemission von Fluoreszenzphotonen: Bremsen
Magnetfeld: Zeemaneffekt vs. Dopplerverschiebung
- B(z) has same shape as v(z) - 10Optical Molassestwo counter propagating lasers to get rid of constant force of the dissipative force
(F_OM ) ⃗=-β ̃v ⃗ β depends on δ(<0: red detuned) → velocity dep. friction force - 11Doppler limitCooling rate in optical molasses equals heat rate due to isotropic emission
T_Doppler1D= ħ γ_10/(2k_B )≈100μK - 12Elastic collisions„good collisions“
total kinetic energy is conserved
only kinetic redistribution
for distinguishable particles σ=4πa^2
for undistinguishable particles r_Boson=8πa^2,σ_Fermion=0
λ=1/nσ
Important for evaporative cooling - 13Inelastic collisions- „Bad collisions“
- loss of energy (kinetic into internal) and far particles
- Restgas collisions
- Dipole relaxion (Coupling of two dipoles ↑↑)
- 3 body-recombination (forming a molecule) - 14BEC-Expansion- uncertainty principle ΔpΔt≥π/2
- interactions between the atoms - 15Measuring velocity distributions- sketch( laser beam frequency vs. velocity distribution)
- same shape of velocity distribution than fluorescence signal
Información
- Descripción
- El usuario ha eliminado su información de asignaturas Fichas sobre Quantum optics-Set 1, creado por Usuario eliminado el 24/09/2017.
- Creado por
- Usuario eliminado · sep 2017
- Actualizado
- 24 sep 2017
- Visitas
- 27
- Historial
-
- Creado por Tom Schobert · 21 sep 2017
- Copiado por Tom Schobert · 24 sep 2017
- Valoración