# The probability of an encounter of photons in nested and double-nested Mach-Zehnder interferometers

## TL;DR

This paper analyzes photon encounters in nested Mach-Zehnder interferometers using classical and quantum optics, demonstrating that certain effects attributed to TSVF are actually due to interference, and interpreting weak values as photon flux encounters.

## Contribution

It clarifies the role of interference in photon detection probabilities and challenges the necessity of TSVF for explaining these effects.

## Key findings

- Interference explains surprising effects without TSVF
- Weak values can be interpreted as photon flux encounters
- No need for unconventional formalism in these scenarios

## Abstract

We present the results of a theoretical work discussing the propagation of an electromagnetic wave through nested Mach-Zehnder interferometers using classical optics and standard quantum theory. We show that some seemingly surprising effects at first sight, which are often explained in the literature using the two-state vector formalism (TSVF), are a direct consequence of destructive or constructive interference and thus there is no need for the unconventional TSVF formulation. We show that the probability of a photon detection derived from the weak value used in TSVF can be interpreted as the probability of an encounter of two opposing photon fluxes.