Jan Peřina

Statistical mixtures of states can be more quantum than their superpositions: Comparison of nonclassicality measures for single-qubit states

A bosonic state is commonly considered nonclassical (or quantum) if its Glauber-Sudarshan

Photon-number distributions of twin beams generated in spontaneous parametric down-conversion and measured by an intensified CCD camera

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Entropy of optical fields

function is not a classical probability density, which implies that only coherent states and their statistical mixtures are classical. We quantify the nonclassicality of a single qubit, defined by the vacuum and single-photon states, by applying the following four well-known measures of nonclassicality: (1) the nonclassical depth,

Higher-order nonclassicalities in a codirectional nonlinear optical coupler: Quantum entanglement, squeezing, and antibunching

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Revealing Hidden Coherence in Partially Coherent Light

, related to the minimal amount of Gaussian noise which changes a nonpositive

Spatial properties of twin-beam correlations at low- to high-intensity transition

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State reconstruction of a multimode twin beam using photodetection

function into a positive one; (2) the nonclassical distance

Non-diffracting beams with controlled spatial coherence

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Optimal sub-Poissonian light generation from twin beams by photon-number resolving detectors

, defined as the Bures distance of a given state to the closest classical state, which is the vacuum for the single-qubit Hilbert space; together with (3) the negativity potential (NP), and (4) concurrence potential, which are the nonclassicality measures corresponding to the entanglement measures (i.e., the negativity and concurrence, respectively) for the state generated by mixing a single-qubit state with the vacuum on a balanced beam splitter. We show that complete statistical mixtures of the vacuum and single-photon states are the most nonclassical single-qubit states regarding the distance

Optimal two-qubit tomography based on local and global measurements: Maximal robustness against errors as described by condition numbers

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