... matrices.¹

The 4 x 4 interferometer response matrices, which describe the transmission of a Stokes vector through an optical element, are called `Mueller' matrices in the optical polarisation literature. The 2 x 2 antenna-based response matrices, which describe the transmission of the instantaneous vector amplitude through an optical element, are called `Jones' matrices. Mueller matrices cannot always be factorised into Jones matrices.

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... path.²

For completeness it should be noted that one of the properties of the direct matrix product is that: ($\vec{J}^{\null}_{i}$ $\otimes$ $\vec{J}^{\ast}_{j}$) = ($\vec{G}^{\null}_{i}$ $\otimes$ $\vec{G}^{\ast}_{j}$) ($\vec{D}^{\null}_{i}$ $\otimes$ $\vec{D}^{\ast}_{j}$) ($\vec{C}^{\null}_{i}$ $\otimes$ $\vec{C}^{\ast}_{j}$) ($\vec{P}^{\null}_{i}$ $\otimes$ $\vec{P}^{\ast}_{j}$) ($\vec{F}^{\null}_{i}$ $\otimes$ $\vec{F}^{\ast}_{j}$) . However, it seems better to work with 2 x 2 matrices as much as possible.

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