Detection of two-mode spatial quantum states of light by electro-optic integrated directional couplers

Abstract: We study both manipulation and detection of two-mode spatial quantum states of light by means of a reconfigurable integrated device built in an electro-optical material in a Kolgelnik-Schmidt configuration, which provides higher error tolerance to fabrication defects and larger integration density than other current schemes. SU(2) transformations are implemented on guided spatial modes in such a way that reconstruction of both the optical field-strength quantum probability distribution, via spatial two-mode homodyne detection, and the full optical field-strength wavefunction, by means of weak values, are carried out. This approach can easily be extended to spatial N-mode input quantum states. Apart from its usefulness to characterize optical quantum states, it is also emphasized its application to the measurement of the so-called generalized quantum polarization.