Polarization state of a biphoton: quantum ternary logic

Polarization state of biphoton light generated via collinear frequency-degenerate spontaneous parametric down-conversion is considered. A biphoton is described by a three-component polarization vector, its arbitrary transformations relating to the SU(3) group. A subset of such transformations, available with retardation plates, is realized experimentally. In particular, two independent orthogonally polarized beams of type-I biphotons are transformed into a beam of type-II biphotons. Polarized biphotons are suggested as ternary analogs of two-state quantum systems (qubits)

Synaptic bistability due to nucleation and evaporation of receptor clusters

We introduce a bistable mechanism for long-term synaptic plasticity based on switching between two metastable states that contain significantly different numbers of synaptic receptors. One state is characterized by a two-dimensional gas of mobile interacting receptors and is stabilized against clustering by a high nucleation barrier. The other state contains a receptor gas in equilibrium with a large cluster of immobile receptors, which is stabilized from growing further by the turnover rate of receptors into and out of the synapse. Transitions between the two states can be initiated by either an increase (potentiation) or a decrease (depotentiation) of the net receptor flux into the synapse. This changes the saturation level of the receptor gas and triggers nucleation or evaporation of receptor clusters

Measurement of qutrits

We proposed the procedure of measuring the unknown state of the three-level system - the qutrit, which was realized as the arbitrary polarization state of the single-mode biphoton field. This procedure is accomplished for the set of the pure states of qutrits; this set is defined by the properties of SU(2) transformations, that are done by the polarization transformers.Comment: 9 pages, 9 figure

Limit quantum efficiency for violation of Clauser-Horne Inequality for qutrits

In this paper we present the results of numerical calculations about the minimal value of detection efficiency for violating the Clauser - Horne inequality for qutrits. Our results show how the use of non-maximally entangled states largely improves this limit respect to maximally entangled ones. A stronger resistance to noise is also found.Comment: Phys. Rev. A in pres

Crystal structures of tribromo(η5-3,6-di-tert-butyl-9,10,11- trimethyl-bicyclo(6.3.0)undeca-4-en-8,10-dienyl)titanium(IV), Ti(C 22H35)Br3, and tribromo(η5-4,5- dibromo-3,6-di-tert-butyl-9,10,11-trimethyl-bicyclo(6.3.0)undeca-8,10-dienyl) titanium(IV), Ti(C22H35Br2)Br3

C22H35Br3Ti, triclinic, P1̄ (no. 2), a = 9.621(2) Å, b = 11.796(2) Å, c = 12.232(2) Å, α = 102.23(3)°, β = 97.71(3)°, γ = 112.32(3)°, V = 1219.2 Å3, Z = 2, Rgt(F) = 0.058, wRobs(F 2) = 0.134, T = 293 K. C22H35Br5Ti, monoclinic, P121/n1 (no. 14), a = 7.474(1) Å, b = 18.458(4) Å, c = 20.171(4) Å, β = 100.28(3)°, V= 2738.0 Å3, Z = 4, Rgt(F) = 0.054, wRobs(F 2) = 0.119, T = 293 K. © by Oldenbourg Wissenchaftsverlag