Non-Gaussian Quantum States and Where to Find Them

Homodyne detection of non-Gaussian quantum steering

“…Thus, we observe that by means of a non-local non-Gaussian operations a finite amount of steering is created for arbitrarily low squeezing. This observation is in agreement with those obtained when measuring entanglement in this kind of non-Gaussian states [32], and can intuitively be understood in the following way: For an arbitrarily low amount of squeez-A→B B→A 0 0.1 0.2 0.3 0.4 0.5 0 1.…”

“…In this Section, we translate the general protocol of the previous Section to the specific context of multimode quantum optics [32,36]. We rely on quadrature displacements as the phase estimation probe, which can easily implemented by shifting the Wigner function [37] in phase space.…”

“…In this Section we will introduce the probe states that we shall consider throughout this paper, namely, photon-subtracted states. Different approaches can be followed to describe the generation of these states and obtain their Wigner function [32,[39][40][41].…”

“…For that, we will consider single-photonsubtracted states as a probe system. In the context of non-Gaussian states, photon subtraction, offers an experimentally feasible way to attain Wigner negativity in a controlled way [32,33]. This approach offers a very flexible way to generate different kind of states [34] and in particular purely non-Gaussian features can be studied by appropriately choosing the mode in which the photon is subtracted [32].…”

Single-mode Quantum Non-Gaussian Light from Warm Atoms

“…However, for the majority of the prospective applications of quantum technologies, a mere nonclassicality cannot provide a boosting resource over the analogous classical approach, but the enhancement must be supplied by the sensitive quantum non-Gaussian (QNG) properties available either as QNG input states or through the controllable nonlinear QNG interactions [3]. By the definition, QNG states hallmark intrinsically nonlinear character of the source [4,5] and already serve as an indispensable resources for the nontrivial character of quantum sensing [6,7], and error correction [8][9][10][11], dominantly for motional states of trapped ions and microwave radiation in the superconducting circuits. Despite of the optical implementations being significantly more challenging, past two decades brought several stimulating proof-of-principle demonstrations of the QNG states from the heralded cavity OPO sources [12][13][14][15][16][17][18][19][20], and recently also from heralded single-atom source [21], signified by the observation of the negativity of Wigner function [22].…”