2,470 research outputs found
Effective-range approach and scaling laws for electromagnetic strength in neutron-halo nuclei
We study low-lying multipole strength in neutron-halo nuclei. The strength
depends only on a few low-energy constants: the neutron separation energy, the
asymptotic normalization coefficient of the bound state wave function, and the
scattering length that contains the information on the interaction in the
continuum. The shape of the transition probability shows a characteristic
dependence on few scaling parameters and the angular momenta. The total E1
strength is related to the root-mean-square radius of the neutron wave function
in the ground state and shows corresponding scaling properties. We apply our
approach to the E1 strength distribution of 11Be.Comment: 4 pages, 1 figure (modified), additional table, extended discussion
of example, accepted for publication in Phys. Rev. Let
Pure single photons from a trapped atom source
Single atoms or atom-like emitters are the purest source of on-demand single
photons, they are intrinsically incapable of multi-photon emission. To
demonstrate this degree of purity we have realized a tunable, on-demand source
of single photons using a single ion trapped at the common focus of high
numerical aperture lenses. Our trapped-ion source produces single-photon pulses
at a rate of 200 kHz with g, without any
background subtraction. The corresponding residual background is accounted for
exclusively by detector dark counts. We further characterize the performance of
our source by measuring the violation of a non-Gaussian state witness and show
that its output corresponds to ideal attenuated single photons. Combined with
current efforts to enhance collection efficiency from single emitters, our
results suggest that single trapped ions are not only ideal stationary qubits
for quantum information processing, but promising sources of light for scalable
optical quantum networks.Comment: 7 pages plus one page supplementary materia
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