Non-Phi(0)-periodic macroscopic quantum interference in one-dimensional parallel Josephson junction arrays with unconventional grating structure - art. no. 024511

A theoretical study is presented for a number N of Josephson junctions conn ected as a one-dimensional (1D) parallel array in such a manner that there an N-1 individual superconducting loops with arbitrary shape formed. In the resistive array mode, for bias currents I>I-c, all Josephson junctions in the array oscillate at the same magnetic held dependent frequency nu (B) wh ich is, in general, not a Phi (0)-periodic function of the strength of magn etic field B. Within the range of validity of the resistively and capacitiv ely shunted junction (RCSJ) model the periodicity of nu (B) is controlled b y the array geometry alone and does not depend on the distribution of the a rray junction parameters. In the overdamped junction regime, nu (B) is for certain types of unconventional grating structures a unique function around a sharp global minimum at B=0. This filter property does not apply for reg ular gratings and superconducting quantum interference devices (SQUID's). C omputer simulations of the full nonlinear array dynamics reveal that the qu alitative macroscopic quantum interference properties of unconventional arr ays are governed, irrespective of the strength of inductive couplings, by a complex structure factor S-N(B) which can be determined analytically. Also , the performance of magnetometers based on ID arrays with unconventional g rating structure can be significantly better than the performance of conven tional SQUID's. In particular, ID arrays with unconventional grating struct ure should provide a technically lather unsophisticated precision measureme nt of absolute strength and orientation of external magnetic fields.