Simulation of cooling and atom loss rates in forced evaporation

In this presentation, we outline a technique for numerically simulating atom losses during forced evaporative cooling. This same technique can also be used to estimate Majorana spin flip losses at the hole of a quadrupole trap. Our procedure uses a Metropolis-Hastings algorithm to sample trajectories from a thermal distribution. Then, the nuclear coordinates of atoms are taken to be classical, and the energy shift due to the linear Zeeman effect gives a shift in energy levels parameterized in time by E∝|B(r(t))|. As atoms reach points of closest and furthest approach (i.e. near the central hole or the RF knife), trapped states may non-adiabatically tunnel into anti-trapped spin states at the avoided crossing. Since atoms undergo quasi-periodic motion, the probability of a spin state transition may be averaged over many orbits to calculate an effective loss rate.