  In this review, we discuss recent developments concerning efficient
calculations of multi-loop multi-leg scattering amplitudes. Inspired by the
remarkable properties of the Loop-Tree Duality (LTD), we explain how to
reconstruct an integrand level representation of scattering amplitudes which
only contains physical singularities. These so-called causal representations
can be derived from connected binary partitions of Feynman diagrams, properly
entangled according to specific rules. We will focus on the detection of flux
orientations which are compatible with causality, describing the implementation
of a quantum algorithm to identify such configurations.
