10,244 research outputs found
Generation of Hyperentangled Photons Pairs
We experimentally demonstrate the first quantum system entangled in every
degree of freedom (hyperentangled). Using pairs of photons produced in
spontaneous parametric downconversion, we verify entanglement by observing a
Bell-type inequality violation in each degree of freedom: polarization, spatial
mode and time-energy. We also produce and characterize maximally hyperentangled
states and novel states simultaneously exhibiting both quantum and classical
correlations. Finally, we report the tomography of a 2x2x3x3 system
(36-dimensional Hilbert space), which we believe is the first reported photonic
entangled system of this size to be so characterized.Comment: 5 pages, 3 figures, 1 table, published versio
Testable two-loop radiative neutrino mass model based on an effective operator
A new two-loop radiative Majorana neutrino mass model is constructed from the
gauge-invariant effective operator that violates lepton number conservation by two units. The
ultraviolet completion features two scalar leptoquark flavors and a color-octet
Majorana fermion. We show that there exists a region of parameter space where
the neutrino oscillation data can be fitted while simultaneously meeting
flavor-violation and collider bounds. The model is testable through lepton
flavor-violating processes such as , , and
conversion, as well as collider searches for the scalar
leptoquarks and color-octet fermion. We computed and compiled a list of
necessary Passarino-Veltman integrals up to boxes in the approximation of
vanishing external momenta and made them available as a Mathematica package,
denoted as ANT.Comment: 42 pages, 11 figures, typo in Eq. (4.9) as well as wrong chirality
structures in Secs. 4.5 and 5.2 corrected, final results unchange
Commentary on Kraiss et al.: Read the label - improving the applicability of systematic reviews by coding and analysis of intervention elements
While controlled trials are crucial for establishing an intervention's effectiveness, knowing what was assessed and what it was compared to is often mysterious. Trustworthy replication and application both require a sufficiently clear ‘recipe’ for the experimental and control interventions that other researchers and clinicians could use them. This problem of description is further complicated our fuzzy language: phrases such as ‘brief physician advice’, ‘nurse counselling’, ‘self-help’ and ‘usual care’ can each give the illusion of a singular, well-delineated intervention. The study by Kraiss et al. [1] demonstrates just how illusory this can be for both intervention and the usual care. More importantly, they demonstrate how the elements of intervention and usual care might be unravelled. Such methods are vital for both research progress and for real-world application
Measurement of geometric phase for mixed states using single photon interferometry
Geometric phase may enable inherently fault-tolerant quantum computation.
However, due to potential decoherence effects, it is important to understand
how such phases arise for {\it mixed} input states. We report the first
experiment to measure mixed-state geometric phases in optics, using a
Mach-Zehnder interferometer, and polarization mixed states that are produced in
two different ways: decohering pure states with birefringent elements; and
producing a nonmaximally entangled state of two photons and tracing over one of
them, a form of remote state preparation.Comment: To appear in Phys. Rev. Lett. 4 pages, 3 figure
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