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Chern Numbers Hiding in Time-of-Flight Images



Ian B. Spielman, Erhai Zhao, Noah Bray-Ali, Carl J. Williams, Indubala Satija


We present a novel technique for detecting topological invariants -- Chern numbers -- from time-of-flight images of ultra-cold neutral atoms. The Chern number of fermions in a lattice potential depends on magnetic field (for neutral atoms, generated by an artificial magnetic field) and the chemical potential; we find that the Chern numbers leave their fingerprints as oscillations in the atoms momentum distribution. The signature is strikingly enhanced for anisotropic hopping, where we show the momentum distribution assumes a sinusoidal form with period determined by the Chern number.
Physical Review Letters


artificial gauge fields, time-of-flight images, topological insulators, ultracold atoms


Spielman, I. , Zhao, E. , Bray-Ali, N. , Williams, C. and Satija, I. (2011), Chern Numbers Hiding in Time-of-Flight Images, Physical Review Letters, [online], (Accessed June 20, 2024)


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Created December 21, 2011, Updated November 10, 2018