State Tomography of a Qubit through Scattering of a Probe Qubit

We discuss the state tomography of a fixed qubit (a spin-1/2 target particle), which is in general in a mixed state, through 1D scattering of a probe qubit off the target. Two strategies are presented, by making use of different degrees of freedom of the probe, spin and momentum. Remarkably, the spatial degree of freedom of the probe can be useful for the tomography of the qubit.