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Physical Review A

Spin polarization and quantum-statistical effects in ultracold ionizing collisions

Chad Orzel, M. Walhout, Uwe Sterr, Paul S. Julienne, S. L. Rolston

Published Mar 1, 1999• 39 citations
Publisher

Abstract

We have measured ultracold ionizing collision rates for three bosonic ${(}^{132}\mathrm{Xe},{}^{134}\mathrm{Xe},$ and ${}^{136}\mathrm{Xe})$ and two fermionic ${(}^{129}\mathrm{Xe}$ and ${}^{131}\mathrm{Xe})$ isotopes of xenon in the $6s[3/2{]}_{2}$ metastable state, for both spin-polarized and unpolarized samples. For unpolarized samples at temperatures above the p-wave centrifugal barrier $(\ensuremath{\sim}39 \ensuremath{\mu}\mathrm{K}),$ we find that collision rates for all isotopes are identical. Quantum-statistical effects forbid s-wave collisions for spin-polarized fermions, giving rise to significant differences between bosonic and fermionic isotopes below the p-wave barrier. We present a technique for measuring collision rates at temperatures below $1 \ensuremath{\mu}\mathrm{K},$ and find that the ratio of polarized to unpolarized collision rates for fermions decreases by a factor of 2 at low temperatures, while the ratio for bosons increases by $50%.$ We find no evidence of an overall reduction in the collision rate for spin-polarized samples, as has been observed in metastable helium. These results are explained using a simple theoretical model of transmission and quantum reflection off long-range interatomic potentials.

DOI
10.1103/physreva.59.1926

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