Onsager-Manning-Oosawa condensation phenomenon and the effect of salt

Making use of results pertaining to Painleve III type equations, we revisit the celebrated Onsager-Manning-Oosawa condensation phenomenon for charged stiff linear polymers, in the mean-field approximation with salt. We obtain analytically the associated critical line charge density, and show that it is severely affected by finite salt effects, whereas previous results focused on the no salt limit. In addition, we obtain explicit expressions for the condensate thickness and the electric potential. The case of asymmetric electrolytes is also briefly addressed.Comment: to appear in Phys. Rev. Let

Planck-Scale Effects on Global Symmetries: Cosmology of Pseudo-Goldstone Bosons

We consider a model with a small explicit breaking of a global symmetry, as suggested by gravitational arguments. Our model has one scalar field transforming under a non-anomalous U(1) symmetry, and coupled lo matter and to gauge bosons. The spontaneous breaking of the explicitly broken symmetry gives rise to a massive pseudo-Goldstone boson. We analyze thermal and non-thermal production of this particle in the early universe, and perform a systematic study of astrophysical and cosmological constraints on its properties. We find that for very suppressed explicit breaking the pseudo-Goldstone boson is a cold dark matter candidate.Comment: 31 pages, 9 figures, Latex file; sections 3 and 4 merged; sections 5 and 6 merged; appendix B removed; to be published in Phys Rev

A Gillespie algorithm for efficient simulation of quantum jump trajectories

The jump unravelling of a quantum master equation decomposes the dynamics of an open quantum system into abrupt jumps, interspersed by periods of coherent dynamics where no jumps occur. Simulating these jump trajectories is computationally expensive, as it requires very small time steps to ensure convergence. This computational challenge is aggravated in regimes where the coherent, Hamiltonian dynamics are fast compared to the dissipative dynamics responsible for the jumps. Here, we present a quantum version of the Gillespie algorithm that bypasses this issue by directly constructing the waiting time distribution for the next jump to occur. In effect, this avoids the need for timestep discretisation altogether, instead evolving the system continuously from one jump to the next. We describe the algorithm in detail and discuss relevant limiting cases. To illustrate it we include four example applications of increasing physical complexity. These additionally serve to compare the performance of the algorithm to alternative approaches -- namely, the widely-used routines contained in the powerful Python library QuTip. We find significant gains in efficiency for our algorithm and discuss in which regimes these are most pronounced. Publicly available implementations of our code are provided in Julia and Mathematica.Comment: 13 pages, 4 figures. Comments welcom

Draft Genome Sequence of the Caffeine-Degrading Methylotroph Methylorubrum populi Pinkel.

A pink-pigmented facultative methylotroph, Methylorubrum populi Pinkel, was isolated from compost by selective enrichment with caffeine (3,5,7-trimethylxanthine) as the sole carbon, nitrogen, and energy source. We report here its high-quality draft genome sequence, assembled in 35 contigs totaling 5,630,907 bp. We identified 5,681 protein-coding sequences, including those putatively involved in caffeine degradation