Bidirectional coherent classical communication

A unitary interaction coupling two parties enables quantum communication in both the forward and backward directions. Each communication capacity can be thought of as a tradeoff between the achievable rates of specific types of forward and backward communication. Our first result shows that for any bipartite unitary gate, coherent classical communication is no more difficult than classical communication -- they have the same achievable rate regions. Previously this result was known only for the unidirectional capacities (i.e., the boundaries of the tradeoff). We then relate the tradeoff curve for two-way coherent communication to the tradeoff for two-way quantum communication and the tradeoff for coherent communiation in one direction and quantum communication in the other.Comment: 11 pages, v2 extensive modification and rewriting of the main proof, v3 published version with only a few more change

Charge carrier correlation in the electron-doped t-J model

We study the t-t'-t''-J model with parameters chosen to model an electron-doped high temperature superconductor. The model with one, two and four charge carriers is solved on a 32-site lattice using exact diagonalization. Our results demonstrate that at doping levels up to x=0.125 the model possesses robust antiferromagnetic correlation. When doped with one charge carrier, the ground state has momenta (\pm\pi,0) and (0,\pm\pi). On further doping, charge carriers are unbound and the momentum distribution function can be constructed from that of the single-carrier ground state. The Fermi surface resembles that of small pockets at single charge carrier ground state momenta, which is the expected result in a lightly doped antiferromagnet. This feature persists upon doping up to the largest doping level we achieved. We therefore do not observe the Fermi surface changing shape at doping levels up to 0.125

MHC Restriction of V-V Interactions in Serum IgG

According to Jerne’s idiotypic network hypothesis, the adaptive immune system is regulated by interactions between the variable regions of antibodies, B cells, and T cells. The symmetrical immune network theory is based on Jerne’s hypothesis, and provides a basis for understanding many of the phenomena of adaptive immunity. The theory includes the postulate that the repertoire of serum IgG molecules is regulated by T cells, with the result that IgG molecules express V region determinants that mimic V region determinants present on suppressor T cells. In this paper we describe rapid binding between purified murine serum IgG of H-2b and H-2d mice and serum IgG from the same strain and from MHC-matched mice, but not between serum IgG preparations of mice with different MHC genes. We interpret this surprising finding in terms of a model in which IgG molecules are selected to have both anti-anti-self MHC and anti-anti-anti-self MHC specificity