# Squeezing as an irreducible resource

**Authors:** Samuel L. Braunstein  
**arXiv:** [quant-ph/9904002](https://arxiv.org/abs/quant-ph/9904002)  
**Date:** 1999-04-01  
**Summary page:** https://www.summarizepaper.com/fr/arxiv-id/quant-ph--9904002v2/

## Abstract

We show that squeezing is an irreducible resource which remains invariant under transformations by linear optical elements. In particular, we give a decomposition of any optical circuit with linear input-output relations into a linear multiport interferometer followed by a unique set of single mode squeezers and then another multiport interferometer. Using this decomposition we derive a no-go theorem for superpositions of macroscopically distinct states from single-photon detection. Further, we demonstrate the equivalence between several schemes for randomly creating polarization-entangled states. Finally, we derive minimal quantum optical circuits for ideal quantum non-demolition coupling of quadrature-phase amplitudes.