Quantum changes in conductance are observed at room temperature during the separation of two macroscopic contacts. In this case the separation is induced by vibrations in the experimental apparatus and the conductance is measured as a function of time by a digital oscilloscope. While in most cases this separation leads to a complete breaking of the electrical contact (inset) usually with a final conductance of a single quantum (2e^2/h), we also observe cases where the conductance changes reversibly (main plot) when the separtion is not complete, but instead returns to full contact. The explanation of these observations lies in the creation of small nanometer-scale wires at the final stages of the contact separation.

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