halo

Simulation of colliding Bose-Einstein condensates in producing momentum-correlated pairs of atoms. S-wave scattering and T-F approximation are used in the simulation model. Scattering halo qualitatively resembling experiments are produced and data analysis is undertaken to quantify number squeezing and momentum correlation.

Package

MATLAB scripts

• halo.m
• halo_sim.m
• halo_analyse.m (RENAME this file)
• g2_BB.m
• g2_histo.m
• g2_gauss_fit.m
• g2_ogren_kheruntsyan.m
• pairsum.m
• ballfilter.m

Instructions

1. Configure simulation parameters in halo.m: N_sim, N_halo, QE, N_0, P_dist, w_trap, zone_frac, Nz_polar, Nz_azim
2. Run halo.m script Explain what the script does
3. Configure parameters in g2_BB.m: p_delta
4. Run g2_BB.m Explain what the script does
5. Run g2_gauss_fit.m explain
6. Run g2_ogren_kheruntsyan.m explain

He* BEC collision experiment

• Raman/Bragg laser wavelength: 1083nm
• He* s-wave scattering length: a_He = 7.5nm
• He4 mass: m_He = 6.65e-27 kg

BEC momentum distribution

Ogren-Kheruntsyan

• Width of the momentum distribution of the source condensate (TF approx) along direction i w(S)_i =~ 1.99/R_i

Thomas-Fermi approximation of BEC wavefunction

• Thomas-Fermi radius: R_i = sqrt(2mu/(momega_i^2))
• Chemical potential: mu = (15N_0a/abar)^0.4hbaromega_avg/2

BEC parameters

• Characteristic length of oscillator: abar = sqrt(hbar/(m*omega_avg))
• Oscillator frequency: omega_avg = (omega_1omega_2omega_3)^(1/3)
• Condensate population: N_0