Fermionic coherent states for pseudo-Hermitian two-level systems

We introduce creation and annihilation operators of pseudo-Hermitian fermions for two-level systems described by pseudo-Hermitian Hamiltonian with real eigenvalues. This allows the generalization of the fermionic coherent states approach to such systems. Pseudo-fermionic coherent states are constructed as eigenstates of two pseudo-fermion annihilation operators. These coherent states form a bi-normal and bi-overcomplete system, and their evolution governed by the pseudo-Hermitian Hamiltonian is temporally stable. In terms of the introduced pseudo-fermion operators the two-level system' Hamiltonian takes a factorized form similar to that of a harmonic oscillator.Comment: 13 pages (Latex, article class), no figures; v2: some amendments in section 2, seven new refs adde

High-angle optically accessible Brewster cavity exciton-polaritons

We report on the observation of the strong-coupling regime between quantum well excitons and a high incidence “Brewster cavity mode” previously identified as the generalized Brewster angle condition in multilayer structures [H. F. Mahlein, J. Opt. Soc. Am. 64, 647 (1974)]. This propagating mode is inside the light cone and therefore can be accessed from the top side of the sample without the need for prism or grating coupling methods. The observed anticrossing is clear evidence of the strong light-matter coupling regime. All the results are accurately reproduced by transfer matrix simulations. These results demonstrate the high potential of such structures for the study of propagating polaritons at high k, which could be harnessed for the realization of polaritonic circuit devices.Financial support from the bilateral Greece-Russia Polisimulator project cofinanced by Greece and the EU Regional Development Fund, Russian Science Foundation Grants No. 19-72-20120, UK EPSRC EP/L027151/1, EP/N016920/1 grants are acknowledged. The research was cofinanced by Greece and EU-ESF Fund through HRDELL 2014-2020 program (project MIS 5004464)

Coherent states for the hydrogen atom: discrete and continuous spectra

We construct the systems of generalised coherent states for the discrete and continuous spectra of the hydrogen atom. These systems are expressed in elementary functions and are invariant under the $SO(3, 2)$ (discrete spectrum) and $SO(4, 1)$ (continuous spectrum) subgroups of the dynamical symmetry group $SO(4, 2)$ of the hydrogen atom. Both systems of coherent states are particular cases of the kernel of integral operator which interwines irreducible representations of the $SO(4, 2)$ group.Comment: 15 pages, LATEX, minor sign corrections, to appear in J.Phys.

Squeezing of a coupled state of two spinors

The notion of spin squeezing involves reduction in the uncertainty of a component of the spin vector below a certain limit. This aspect has been studied earlier for pure and mixed states of definite spin. In this paper, this study has been extended to coupled spin states which do not possess sharp spin value. A general squeezing criterion has been obtained by requiring that a direct product state for two spinors is not squeezed. The squeezing aspect of entangled states is studied in relation to their spin- spin correlations.Comment: Typeset in LaTeX 2e using the style iopart, packages iopams,times,amssymb,graphicx; 17 pages, 5 eps figure file

Berry phases for the nonlocal Gross-Pitaevskii equation with a quadratic potential

A countable set of asymptotic space -- localized solutions is constructed by the complex germ method in the adiabatic approximation for the nonstationary Gross -- Pitaevskii equation with nonlocal nonlinearity and a quadratic potential. The asymptotic parameter is 1/T, where $T\gg1$ is the adiabatic evolution time. A generalization of the Berry phase of the linear Schr\"odinger equation is formulated for the Gross-Pitaevskii equation. For the solutions constructed, the Berry phases are found in explicit form.Comment: 13 pages, no figure

Electrical tuning of nonlinearities in exciton-polariton condensates

S. T. acknowledges the financial support of the Stavros Niarchos Foundation within the framework of the project ARCHERS, P. S. acknowledges support form the bilateral Greece-Russia Polisimulator project cofinanced by Greece and the EU Regional Development Fund, A. T. acknowledges the Russian-Greek support from the project supported by the Ministry of Education and Science of The Russian Federation (Project No. RFMEFI61617X0085).A primary limitation of the intensively researched polaritonic systems compared to their atomic counterparts for the study of strongly correlated phenomena and many-body physics is their relatively weak two-particle interactions compared to disorder. Here, we show how new opportunities to enhance such on-site interactions and nonlinearities arise by tuning the exciton-polariton dipole moment in electrically biased semiconductor microcavities incorporating wide quantum wells. The applied field results in a twofold enhancement of exciton-exciton interactions as well as more efficiently driving relaxation towards low energy polariton states, thus, reducing condensation threshold.PostprintPeer reviewe

Self-reported adverse reactions in 4337 healthcare workers immunizations against novel H1N1 influenza

Purpose: The use of the 2009 H1N1 vaccine has generated much debate concerning safety issues among the general population and physicians. Therefore, we investigated the safety of an inactivated monovalent H1N1 pandemic influenza vaccine Methods: We focused on the H1N1 pandemic influenza vaccine Pandemrix(R) and applied a self reporting questionnaire in a population of healthcare workers (HCWs) and medical students at a major university hospital. Results: In total, 4337 individuals were vaccinated, consisting of 3808 HCWs and 529 medical students. The vaccination rate of the employees was higher than 40%.The majority of individuals were vaccinated in November 2009. In total, 291 of the 4337 vaccinations were reported to lead to one or more adverse reactions (6.7%). Local reactions were reported in 3.8%, myalgia and arthralgia in 3.7%, fatigue in 3.7%, headache in 3.1%. Conclusions: Our data together with available data from several national and international institutions points to a safe pandemic influenza vaccine

Chromosomal-level assembly of the Asian Seabass genome using long sequence reads and multi-layered scaffolding

We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics