01229nas a2200169 4500008004100000245005000041210004800091260001500139490000700154520075700161100001600918700001900934700002300953700002100976700002500997856003701022 2011 eng d00aChern numbers hiding in time-of-flight images0 aChern numbers hiding in timeofflight images c2011/12/210 v843 a We present a technique for detecting topological invariants -- Chern numbers
-- from time-of-flight images of ultra-cold atoms. We show that the Chern
numbers of integer quantum Hall states of lattice fermions leave their
fingerprints in the atoms' momentum distribution. We analytically demonstrate
that the number of local maxima in the momentum distribution is equal to the
Chern number in two limiting cases, for large hopping anisotropy and in the
continuum limit. In addition, our numerical simulations beyond these two limits
show that these local maxima persist for a range of parameters. Thus, an
everyday observable in cold atom experiments can serve as a useful tool to
characterize and visualize quantum states with non-trivial topology.
1 aZhao, Erhai1 aBray-Ali, Noah1 aWilliams, Carl, J.1 aSpielman, I., B.1 aSatija, Indubala, I. uhttp://arxiv.org/abs/1105.3100v3