Limitation of the modulation method to smooth wire guide roughness

TL;DR

This paper investigates the limitations of using current modulation to smooth wire guide roughness in atom traps, analyzing heating, loss rates, and conditions for evaporative cooling to optimize the technique.

Contribution

It provides a theoretical analysis of the modulation method's limitations, including heating effects, loss mechanisms, and conditions for effective cooling.

Findings

Heating rate increases at low modulation frequency.

Resonances cause loss at certain high modulation frequencies.

Modulation technique is effective over a wide parameter range.

Abstract

It was recently demonstrated that wire guide roughness can be suppressed by modulating the wire currents so that the atoms experience a time-averaged potential without roughness. We theoretically study the limitations of this technique. At low modulation frequency, we show that the longitudinal potential modulation produces a heating of the cloud and we compute the heating rate. We also give a quantum derivation of the rough conservative potential associated with the micro-motion of the atoms. At large modulation frequency, we compute the loss rate due to non adiabatic spin flip and show it presents resonnances at multiple modulation frequencies. These studies show that the modulation technique works for a wide range of experimental parameters. We also give conditions to realise radio-frequency evaporative cooling in such a modulated trap.