Quantum phase transition in one-dimensional Josephson junction arrays

We describe experiments on one-dimensional arrays of small capacitance Jose phson junctions which show how the Coulomb blockade of Cooper pair tunnelin g is influenced by changing the Josephson coupling energy in situ with an e xternally applied magnetic flux. We show how the zero bias resistance of th e array is affected by the length of the array, and we use the length scali ng of this resistance to infer that a quantum phase transition occurs as th e Josephson coupling energy is changed. The data are qualitatively analyzed in terms of a theoretical model of the quantum phase transition which uses a mapping to the two-dimensional XY model. (C) 2001 Elsevier Science B.V. All rights reserved.