Entangled photon polarimetry

Aaron Z. Goldberg

Jinliang Ren, Vira Besaga, Ivan Lopushenko +5 more

Conventional polarimetry, including schemes leveraging entangled light, characterizes optical samples through linear transformations of polarization states. We introduce a two-photon probing approach in which both photons of an entangled pair interact with the same depolarizing medium simultaneously. In this regime, the transformation of the two-photon polarization correlations becomes quadratic in the Mueller matrix, enabling access to second-order polarization information beyond conventional polarimetry. We develop a theoretical framework linking the Mueller matrix to the evolution of the two-photon polarization correlation tensor and show that depolarization induces quadratic degradation of entanglement and state purity. Experiments using polarization-entangled photon pairs transmitted through controlled scattering media confirm the predicted response and reveal enhanced sensitivity to polarization scrambling compared with single-photon probing. These results establish two-photon probing as a higher-order quantum polarimetric modality for characterizing polarization channels.

Ayman F. Abouraddy

Chan Ju You, Valeria Rodríguez-Fajardo, Leia Francis +1 more

We present a method to determine the Mueller matrix of a sample using polarization-entangled photon pairs. One of the photons of a pair goes through a sample and is then subject to a polarization projection measurement. The other photon, which does not go through the sample, is also subject to a polarization projection. The measured quantum correlations are equivalent to polarimetry measurements, where the initial state of the photon going through the sample is determined by the polarization projection on the entangled partner that does not go through the sample. The correspondence with the classical system is acausal because quantum measurements apply to distinct Hilbert spaces. We tested this method with standard optical elements finding excellent agreement with the expectations. Thus it can be used as an alternative to classical Mueller polarimetry for conditions that would be challenging to do otherwise.

Krishna Thyagarajan

D. P. Agapov, I. A. Belovolov, Sergey A Magnitskiy +1 more

The first experimental implementation of ghost polarimetry using quantum light is presented. The object is irradiated by one of the photons of an entangled pair generated by SPDC source. Objects whose polarization properties can be interpreted as linear dichroism are used. The coincidence counting technique is used to measure the distribution of the polarization properties of the object.