We discuss how continous-variable quantum states such as coherent states and two-mode squeezed states can be encoded in phase-reference independent ways.
@article{arxiv.quant-ph/0303096,
title = {On continuous-variable entanglement with and without phase references},
author = {S. J. van Enk and Terry Rudolph},
journal= {arXiv preprint arXiv:quant-ph/0303096},
year = {2007}
}