Directly estimating non-classicality
arXiv:1005.1665 · doi:10.1103/PhysRevLett.106.010403
Abstract
We establish a method of directly measuring and estimating non-classicality - operationally defined in terms of the distinguishability of a given state from one with a positive Wigner function. It allows to certify non-classicality, based on possibly much fewer measurement settings than necessary for obtaining complete tomographic knowledge, and is at the same time equipped with a full certificate. We find that even from measuring two conjugate variables alone, one may infer the non-classicality of quantum mechanical modes. This method also provides a practical tool to eventually certify such features in mechanical degrees of freedom in opto-mechanics. The proof of the result is based on Bochner's theorem characterizing classical and quantum characteristic functions and on semi-definite programming. In this joint theoretical-experimental work we present data from experimental optical Fock state preparation, demonstrating the functioning of the approach.
4+1 pages, 2 figures, minor changes
References in corpus (11)
- Entanglement detection
- Radiation-pressure cooling and optomechanical instability of a micro-mirror
- Self-cooling of a micro-mirror by radiation pressure
- Generation of a superposition of odd photon number states for quantum information networks
- Assessing non-Markovian dynamics
- Measuring measurement
- Increasing entanglement between Gaussian states by coherent photon subtraction
- Estimating entanglement measures in experiments
- Spin squeezing of atomic ensembles via nuclear-electronic spin entanglement
- High purity bright single photon source
- When are correlations quantum? -- Verification and quantification of entanglement by simple measurements