Demonstration of active routing of entanglement in a multi-user network

We implement an entanglement distribution network based on wavelength-multiplexing and optical switching for quantum communication applications. Using a high-brightness source based on spontaneous parametric down-conversion in periodically-poled lithium niobate waveguides, we generate polarisation entangled photon pairs with a broad spectrum covering the telecom wavelengths around 1550 nm. The photon pairs have entanglement fidelities up to 99%, and are distributed via passive wavelength multiplexing in a static multi-user network. We furthermore demonstrate a possible network application in a scenario with a single centralised source dynamically allocating two-party entanglement to any pair of users by means of optical switches. The whole system, from the pump laser up to the receivers, is fibre and waveguide based, resulting in maximal stability, minimal losses and the advantage of readily integrable telecom components in the 1550 nm range.

Two-particle separation energy trends in the superdeformed well

A measurement of the energy and spin of superdeformed states in 190Hg, obtained through the observation of transitions directly linking superdeformed and normal states, expands the number of isotopes in which binding energies at superdeformation are known. Comparison with neighboring nuclei shows that two-proton separation energies are higher in the superdeformed state than in the normal state, despite the lower Coulomb barrier and lower total binding energy. This unexpected result provides a critical test for nuclear models.

Shape coexistence near neutron number N=20: first identification of the E0 decay from the deformed first excited Jpi=0+ state in 30Mg

The 1789 keV state in 30Mg was identified as the first excited 0+ state via its electric monopole (E0) transition to the ground state. The measured small value of rho2(E0,0(2)+-->0(1)+)=(26.2+/-7.5)x10(-3) implies within a two-level model a small mixing of competing configurations with largely different intrinsic quadrupole deformation near the neutron shell closure at N=20. Axially symmetric configuration mixing calculations identify the ground state of 30Mg to be based on neutron configurations below the N=20 shell closure, while the excited 0+ state mainly consists of two neutrons excited into the nu 1f7/2 orbital. The experimental result represents the first case where an E0 back decay from a strongly deformed second to the normal deformed first nuclear potential minimum well has been unambiguously identified, thus directly proving shape coexistence at the borderline of the much-debated "island of inversion."

Excitation energies of superdeformed States in 196Pb: towards a systematic study of the second well in Pb isotopes

The excitation energy of the lowest-energy superdeformed band in 196Pb is established using the techniques of time-correlated gamma-ray spectroscopy. Together with previous measurements on 192Pb and 194Pb, this result allows superdeformed excitation energies, binding energies, and two-proton and two-neutron separation energies to be studied systematically, providing stringent tests for current nuclear models. The results are examined for evidence of a "superdeformed shell gap."

Evidence for second-phonon nuclear wobbling

The nucleus 163Lu has been populated through the reaction 139La(29Si,5n) with a beam energy of 157 MeV. Three triaxial, strongly deformed (TSD) bands have been observed with very similar rotational properties. The first excited TSD band has earlier been assigned as a one-phonon wobbling excitation built on the lowest-lying (yrast) TSD band. The large B(E2)(out)/B(E2)(in) value obtainable for one of four observed transitions between the second and first excited TSD bands is in good agreement with particle-rotor calculations for a two-phonon wobbling excitation.

Quadrupole moment of the 11(-) intruder isomer in 196Pb and its implications for the 16(-) shears band head

The quadrupole moment of the 11(-) isomer in 196Pb has been measured by the level mixing spectroscopy method. This state has a pi(3s(-2)(1/2)1h(9/2)1i(13/2))11(-) configuration which is involved in most of the shears band heads in the Pb region. The first directly measured value of Q(s)(11(-)) = (-)3.41(66) b, coupled to the previously known quadrupole moment of the nu(1i(-2)(13/2))12(+) isomer allows us to estimate the quadrupole moment of the 16(-) shears band head as Q(s)(16(-)) = -0.32(10) b. The experimental values are compared to tilted axis cranking calculations, giving insight into the validity of the additivity approach to couple quadrupole moments and on the amount of deformation in the shears bands.

Evidence for the wobbling mode in nuclei

The nucleus (163)Lu has been populated through the fusion-evaporation reaction (139)La((29)Si,5n)(163)Lu with a beam energy of 152 MeV. The electromagnetic properties of several connecting transitions between two presumably triaxial, strongly deformed (TSD) bands have been studied. Evidence is presented for the assignment of the excited TSD band as a wobbling mode built on the yrast TSD band, based on comparisons to new calculations in which an aligned particle is coupled to a strongly deformed triaxial rotor. The wobbling mode is uniquely related to triaxiality in nuclei.

Linear polarization measurement of interband transitions in superdeformed 190hg: model-independent evidence for octupole vibrational structures

The linear polarization of gamma rays between excited and yrast superdeformed (SD) states in 190Hg was measured using the four-element CLOVER detectors of the EUROBALL IV gamma-ray spectrometer. This measurement shows in a model-independent way that the interband transitions which compete with the highly collective in-band quadrupole transitions are largely enhanced electric dipoles. Not only do these results represent the first measurement of the multipolarity of transitions between different SD states, but they also provide strong evidence for the interpretation of the structures in the SD minimum of the A approximately 190 region in terms of octupole excitations.

[Ocular blood flow of cats after local administration of pilocarpine, phenylephrine, and of a mixture of both drugs (author's transl)]

Radioactively labelled microspheres (size 15 micron) were used to determine the regional blood flow in cats before and 15, 30 and 45 minutes after unilateral drug administration. In four experimental groups, each consisting of five animals, two drops of the drug were administered into the conjunctival sac. The blood flow increased in both eyes after administration of 2% pilocarpine and of Glauko Biciron, a mixture of 2% pilocarpine and 0.06% phenylephrine. No significant differences in the regional blood flows between the treated and untreated eye were found. After administration of 2% phenylephrine a decrease in blood flow was observed in both eyes, however earlier and more pronounced in the left eye. Thus, phenylephrine evoked the expected vasoconstrictive effect on the treated side. In the control group, which received physiological salt solution, the blood flow on the treated side decreased in most tissues, while an increase was observed on the untreated side.

[Blood flow through different tissues under clonidine in rabbits (author's transl)]

The effect of i.v. administered clonidine on the blood flow through different tissues was investigated in six rabbits which had been anaesthetized with NembutalR. Six additional animals served as controls and received an equal quantity of a physiological sodium chloride solution. The blood flow was determined by means of radioactively labelled microspheres just before as well as 15, 30 and 45 min after the administration of the drug or the placebo respectively. In most of the investigated tissues a considerable decrease in blood flow was observed 15 min after the injection of clonidine, whereas no effect was to be seen after administration of sodium chloride. For the first time after 30 min, and even more after 45 min the blood flow diminished as well in the control group. The flow-decreasing effect of clonidine occured in lung, skin, choroid, the small intestine, the triceps muscle, the ciliary body, iris, and white matter, whereas the opposite reaction was observed in liver (hepatic artery), retina and the optic nerve.