  We study an Ising chain undergoing a quantum phase transition in a quantum
magnetic field. Such a field can be emulated by coupling the chain to a central
spin initially in a superposition state. We show that - by adiabatically
driving such a system - one can prepare a quantum superposition of any two
ground states of the Ising chain. In particular, one can end up with the Ising
chain in a superposition of ferromagnetic and paramagnetic phases -- a scenario
with no analogue in prior studies of quantum phase transitions. Remarkably, the
resulting magnetization of the chain encodes the position of the critical point
and universal critical exponents, as well as the ground state fidelity.
