Nonclassicality filters and quasiprobabilities

Necessary and sufficient conditions for the nonclassicality of bosonic quantum states are formulated by introducing nonclassicality filters and nonclassicality quasiprobability distributions. Regular quasiprobabilities are constructed from characteristic functions which can be directly sampled by balanced homodyne detection. Their negativities uncover the nonclassical effects of general quantum states. The method is illustrated by visualizing the nonclassical nature of a squeezed state.Comment: Significantly revised version, more emphasis on practical applicatio

Verifying continuous-variable entanglement in finite spaces

Starting from arbitrary Hilbert spaces, we reduce the problem to verify entanglement of any bipartite quantum state to finite dimensional subspaces. Hence, entanglement is a finite dimensional property. A generalization for multipartite quantum states is also given.Comment: 4 page

Reactor antineutrino spectra and their application to antineutrino-induced reactions. II

The antineutrino and electron spectra associated with various nuclear fuels are calculated. While there are substantial differences between the spectra of different uranium and plutonium isotopes, the dependence on the energy and flux of the fission-inducing neutrons is very weak. The resulting spectra can be used for the calculation of the antineutrino and electron spectra of an arbitrary nuclear reactor at various stages of its refueling cycle. The sources of uncertainties in the spectrum are identified and analyzed in detail. The exposure time dependence of the spectrum is also discussed. The averaged cross sections of the inverse neutron β decay, weak charged and neutral-current-induced deuteron disintegration, and the antineutrino-electron scattering are then evaluated using the resulting ν̅_e spectra. [RADIOACTIVITY, FISSION 235U, 238U, (^239)Pu, (^240)Pu, (^241)Pu, antineutrino and electron spectra calculated. σ for ν̅ induced reactions analyzed.

Statistical uncertainty in quantum optical photodetection measurements

We present a complete statistical analysis of quantum optical measurement schemes based on photodetection. Statistical distributions of quantum observables determined from a finite number of experimental runs are characterized with the help of the generating function, which we derive using the exact statistical description of raw experimental outcomes. We use the developed formalism to point out that the statistical uncertainty results in substantial limitations of the determined information on the quantum state: though a family of observables characterizing the quantum state can be safely evaluated from experimental data, its further use to obtain the expectation value of some operators generates exploding statistical errors. These issues are discussed using the example of phase-insensitive measurements of a single light mode. We study reconstruction of the photon number distribution from photon counting and random phase homodyne detection. We show that utilization of the reconstructed distribution to evaluate a simple well-behaved observable, namely the parity operator, encounters difficulties due to accumulation of statistical errors. As the parity operator yields the Wigner function at the phase space origin, this example also demonstrates that transformation between various experimentally determined representations of the quantum state is a quite delicate matter.Comment: 18 pages REVTeX, 7 figures included using epsf. Few minor corrections made, clarified conclusion

Tomographic Characterization of Three-Qubit Pure States with Only Two-Qubit Detectors

A tomographic process for three-qubit pure states using only pairwise detections is presented.Comment: 3 pages; revtex4; v2: the focus on tomography was emphasized and the experimental procedure detailed; v3: the text was improved in clarity, some mistakes were correcte

Neutrinoless Double Beta Decay and Lepton Flavor Violation

We point out that extensions of the Standard Model with low scale (~TeV) lepton number violation (LNV) generally lead to a pattern of lepton flavor violation (LFV) experimentally distinguishable from the one implied by models with GUT scale LNV. As a consequence, muon LFV processes provide a powerful diagnostic tool to determine whether or not the effective neutrino mass can be deduced from the rate of neutrinoless double beta decay. We discuss the role of \mu -> e \gamma and \mu -> e conversion in nuclei, which will be studied with high sensitivity in forthcoming experiments.Comment: 4 pages, 3 figure

How Sensitive are Di-Leptons from Rho Mesons to the High Baryon Density Region?

We show that the measurement of di-leptons might provide only a restricted view into the most dense stages of heavy ion reactions. Thus, possible studies of meson and baryon properties at high baryon densities, as e.g. done at GSI-HADES and envisioned for FAIR-CBM, might observe weaker effects than currently expected in certain approaches. We argue that the strong absorption of resonances in the high baryon density region of the heavy ion collision masks information from the early hot and dense phase due to a strong increase of the total decay width because of collisional broadening. To obtain additional information, we also compare the currently used approaches to extract di-leptons from transport simulations - i.e. shining, only vector mesons from final baryon resonance decays and instant emission of di-leptons and find a strong sensitivity on the method employed in particular at FAIR and SPS energies. It is shown explicitly that a restriction to rho meson (and therefore di-lepton) production only in final state baryon resonance decays provide a strong bias towards rather low baryon densities. The results presented are obtained from UrQMD v2.3 calculations using the standard set-up.Comment: 8 pages, 6 figures, expanded versio

Origin of non-exponential relaxation in a crystalline ionic conductor: a multi-dimensional 109Ag NMR study

The origin of the non-exponential relaxation of silver ions in the crystalline ion conductor Ag7P3S11 is analyzed by comparing appropriate two-time and three-time 109Ag NMR correlation functions. The non-exponentiality is due to a rate distribution, i.e., dynamic heterogeneities, rather than to an intrinsic non-exponentiality. Thus, the data give no evidence for the relevance of correlated back-and-forth jumps on the timescale of the silver relaxation.Comment: 4 pages, 3 figure

Search for Sterile Neutrinos with a Radioactive Source at Daya Bay

The far site detector complex of the Daya Bay reactor experiment is proposed as a location to search for sterile neutrinos with > eV mass. Antineutrinos from a 500 kCi 144Ce-144Pr beta-decay source (DeltaQ=2.996 MeV) would be detected by four identical 20-ton antineutrino targets. The site layout allows flexible source placement; several specific source locations are discussed. In one year, the 3+1 sterile neutrino hypothesis can be tested at essentially the full suggested range of the parameters Delta m^2_{new} and sin^22theta_{new} (90% C.L.). The backgrounds from six nuclear reactors at >1.6 km distance are shown to be manageable. Advantages of performing the experiment at the Daya Bay far site are described