  Here we show that, in principle it is possible to clone (measure) a single
arbitrary unknown quantum state of a spin-$\frac{1}{2}$ particle (an electron)
with arbitrary precision and with success probability tending to one, using
protective measurement. We first transfer the information from spin to spatial
degree of freedom (d.o.f) of system electron, then trap it in a double well
potential, and finally measure it protectively using a probe electron (which
donot get entangled with system electron, but still extracts expectation value
of an observable from a single quantum system (system electron)) to obtain
information about the unknown spin polarization. Nonorthogonal state
discrimination being a subclass of cloning, part of the paper (till finding out
$\theta_{m}$, polar angle corresponding to the unknown spin polarization) is
sufficient for discrimination.
