Schrödinger's Kittens and Non-Gaussian States of the Light: New Tools for Quantum Communications

Philippe Grangier

Philippe Grangier

Philippe Grangier

Alexei Ourjoumtsev

Mohamed Faouzi Melalkia, Juliette Huynh, F. Brunel +3 more

In this work, we study the generation of non-Gaussian quantum states of light using multimode quantum resources. We first propose a theoretical framework to describe photon subtraction operation - a well known non-Gaussian operation - applied to a multimode Gaussian state. We apply this framework to the case of Schrödinger kitten state generation using a multimode squeezed vacuum as input state. We show that a monomode non-Gaussian state with high purity can be generated by a better choice of the different experimental parameters. Then, we propose a new protocol to generate high amplitude non-Gaussian states using spectral multiplexing of input states and Gaussian operations. We show that this protocol can implement the cat breeding operation with less complexity. We show also that this protocol can be used for the generation of approximated GKP state.

Hongbin Song, Katanya B. Kuntz, Elanor H. Huntington

A quantitative analysis is conducted on the impacts of experimental imperfections in the input state, the detector properties, and their interactions on photon-subtracted squeezed vacuum states in terms of a quantum non-Gaussian character witness and Wigner function. Limitations of the non-classicality and quantum non-Gaussian characteristic of Schrödinger kitten states are identified and addressed. The detrimental effects of a photon-number detector on the generation of odd Schrödinger kitten states at near-infrared wavelengths (∼860 nm) and telecommunication wavelengths (∼1550 nm) are presented and analysed. This analysis demonstrates that the high dark count probability of telecommunication-wavelength photon-number detectors significantly undermines the negativity of the Wigner function in Schrödinger kitten state generation experiments. For a one-photon-subtracted squeezed vacuum state at ∼1550 nm, an avalanche photodiode-based photon-number-resolving detector provides no significant advantage over a non-photon-number-resolving detector when imperfections, such as dark count probability and inefficiency, are taken into account.