Constructing a qubit requires something that can be represented as a linear combination of two states. The physical realizations are numerous
But I do not see the use of light polarization in this list. If we let |0> be vertically polarized light and |1> be horizontally polarized light, then a qubit can assume the polarization of light as a sum of these two components. It is easy to read the state of a qubit by measuring the residual brightness after passing the photon through a linear Polaroid filter. The polarization of a qubit can be changed by applying a magnetic field to the photon. The polarization can be stored in a hologram.
Obviously there is a reason no one has done this so perhaps someone can enlighten me.