  Quantum tunneling in an asymmetric (with strongly different capacitances)
SQUID is studied. Since capacitances play a role of masses one phase, related
to a large mass, becomes "heavy" and remains always a constant in a tunneling
process. Tunneling in an asymmetric SQUID becomes one-dimensional with a
condition of optimization of tunneling probability with respect to a value of
the "heavy" phase. An unusual temperature dependence of the tunneling
probability is obtained. It has a finite slope at zero temperature and a
transition between thermally assisted tunneling and pure activation can be not
smooth depending on current through a SQUID.
