  This letter presents fabrication and characterization of an optimized SQUIPT
(superconducting quantum interference proximity transistor). The present
device, characterized with reduced tunnel junction area and shortened
normal-metal section, demonstrates no hysteresis at low temperatures as we
increased the Josephson inductance of the weak link by decreasing its cross
section. It has consequently almost an order of magnitude improved magnetic
field responsivity as compared to the earlier design. The modulation of both
the current and the voltage across the junction have been measured as a
function of magnetic flux piercing the superconducting loop.
