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ABSTRACT: We present a novel shadow evaporation technique for the realization of
junctions and capacitors. The design by E-beam lithography of strongly
asymmetric undercuts on a bilayer resist enables in-situ fabrication of
junctions and capacitors without the use of the well-known suspended bridge.
The absence of bridges increases the mechanical robustness of the resist mask
as well as the accessible range of the junction size, from 0.01 to more than
10000 micron square. We have fabricated Al/AlOx/Al Josephson junctions, phase
qubit and capacitors using a 100kV E- beam writer. Although this high voltage
enables a precise control of the undercut, implementation using a conventional
20kV E-beam is also discussed. The phase qubit coherence times, extracted from
spectroscopy resonance width, Rabi and Ramsey oscillations decay and energy
relaxation measurements, are longer than the ones obtained in our previous
samples realized by standard techniques. These results demonstrate the high
quality of the junction obtained by this controlled undercut technique.