Phase-locking in a nonuniform array of tunnel junctions

A nonuniform, one-dimensional tunnel junction array that is designed to promote phase-locking to an ac pump signal is proposed and theoretically investigated for possible information processing applications. The tunnel resistances of the junctions in one part of the array are tailored to provide phase restoration for electrons tunneling in the array, while the tunnel resistances in the other part of the array are designed to provide a time delay with minimal jitter. It is shown that phase-locking of the tunneling is possible at the fundamental and at the one-half subharmonic of the pump frequency. While the required parameter ranges and the necessary degree of control of this design are not practical for tunneling phase logic based on conventional tunnel junction technologies, the proposed design could potentially be realized in a molecular system. (C) 2003 American Institute of Physics.