Testing nonclassicality and non-gaussianity in phase space

Jiyong Park, Junhua Zhang, Jaehak Lee, Se Wan Ji, Mark Um, Dingshun Lv, Kihwan Kim, Hyunchul Nha

Research output: Contribution to journalArticle

17 Citations (Scopus)


We theoretically propose and experimentally demonstrate a nonclassicality test of a single-mode field in phase space, which has an analogy with the nonlocality test proposed by Banaszek and Wódkiewicz [Phys. Rev. Lett. 82, 2009 (1999)]. Our approach to deriving the classical bound draws on the fact that the Wigner function of a coherent state is a product of two independent distributions as if the orthogonal quadratures (position and momentum) in phase space behave as local realistic variables. Our method detects every pure nonclassical Gaussian state, which can also be extended to mixed states. Furthermore, it sets a bound for all Gaussian states and their mixtures, thereby providing a criterion to detect a genuine quantum non-Gaussian state. Remarkably, our phase-space approach with invariance under Gaussian unitary operations leads to an optimized test for a given non-Gaussian state. We experimentally show how this enhanced method can manifest quantum non-Gaussianity of a state by simply choosing phase-space points appropriately, which is essentially equivalent to implementing a squeezing operation on a given state.

Original languageEnglish
Article number190402
JournalPhysical Review Letters
Issue number19
Publication statusPublished - 15 May 2015


ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Park, J., Zhang, J., Lee, J., Ji, S. W., Um, M., Lv, D., Kim, K., & Nha, H. (2015). Testing nonclassicality and non-gaussianity in phase space. Physical Review Letters, 114(19), [190402]. https://doi.org/10.1103/PhysRevLett.114.190402