Avron J. E. and Berger J.
Adiabatic Response of Quantum Systems Pinching a Gap Closure
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ABSTRACT.  A vanishing cause can lead to a large response in quantum systems which
undergo cyclic deformations that pinch a point of level crossing.  We call
such behavior homeopathic. We illustrate this behavior by studying  charge
circulation in quantum models of necklaces of atoms  driven by a running
wave of small amplitude.