Jiannis K. Pachos, Emilio Alba, Ville Lahtinen, Juan J. Garcia-Ripoll
The Chern number, a topological invariant characterising the ground state of fermionic systems, is a definitive theoretical signature that determines whether a given superconducting system can support Majorana zero modes. Here we show that it can be faithfully reproduced through a set of time-of-flight measurements, making it a diagnostic tool also in actual cold atom experiments. We demonstrate the measurement scheme by employing a chiral topological model of spinless fermions that only requires the experimentally accessible s-wave pairing and staggered tunnelling that mimics spin-orbit coupling. By adiabatically connecting this model to Kitaev's honeycomb lattice model, we show that it gives rise to nu = \pm 1 phases, where vortices carry Majorana fermions, and nu=\pm 2 phases that emerge as a collective state of localised Majorana fermions. Hence, the preparation of these phases and the detection of their Chern numbers provides an unambiguous signature for the presence of Majorana modes. Finally, we demonstrate that our detection procedure is resilient against most inaccuracies in experimental control parameters as well as finite temperature.
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http://arxiv.org/abs/1209.5115
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