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Revealing nonclassicality beyond Gaussian states via a single marginal distribution
- Source :
- PNAS 114 (5), 891-896 (2017)
- Publication Year :
- 2017
-
Abstract
- A standard method to obtain information on a quantum state is to measure marginal distributions along many different axes in phase space, which forms a basis of quantum state tomography. We theoretically propose and experimentally demonstrate a general framework to manifest nonclassicality by observing a single marginal distribution only, which provides a novel insight into nonclassicality and a practical applicability to various quantum systems. Our approach maps the 1-dim marginal distribution into a factorized 2-dim distribution by multiplying the measured distribution or the vacuum-state distribution along an orthogonal axis. The resulting fictitious Wigner function becomes unphysical only for a nonclassical state, thus the negativity of the corresponding density operator provides an evidence of nonclassicality. Furthermore, the negativity measured this way yields a lower bound for entanglement potential---a measure of entanglement generated using a nonclassical state with a beam splitter setting that is a prototypical model to produce continuous-variable (CV) entangled states. Our approach detects both Gaussian and non-Gaussian nonclassical states in a reliable and efficient manner. Remarkably, it works regardless of measurement axis for all non-Gaussian states in finite-dimensional Fock space of any size, also extending to infinite-dimensional states of experimental relevance for CV quantum informatics. We experimentally illustrate the power of our criterion for motional states of a trapped ion confirming their nonclassicality in a measurement-axis independent manner. We also address an extension of our approach combined with phase-shift operations, which leads to a stronger test of nonclassicality, i.e. detection of genuine non-Gaussianity under a CV measurement.<br />Comment: 6 pages, 4 figures with Supplemental Information
- Subjects :
- Quantum Physics
Subjects
Details
- Database :
- arXiv
- Journal :
- PNAS 114 (5), 891-896 (2017)
- Publication Type :
- Report
- Accession number :
- edsarx.1702.01387
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1073/pnas.1617621114