Search results for "Mixed states"
showing 5 items of 5 documents
Purification of Lindblad dynamics, geometry of mixed states and geometric phases
2015
We propose a nonlinear Schr\"odinger equation in a Hilbert space enlarged with an ancilla such that the partial trace of its solution obeys to the Lindblad equation of an open quantum system. The dynamics involved by this nonlinear Schr\"odinger equation constitutes then a purification of the Lindbladian dynamics. This nonlinear equation is compared with other Schr\"odinger like equations appearing in the theory of open systems. We study the (non adiabatic) geometric phases involved by this purification and show that our theory unifies several definitions of geometric phases for open systems which have been previously proposed. We study the geometry involved by this purification and show th…
Bounds on the entanglement of two-qutrit systems from fixed marginals
2019
We discuss the problem of characterizing upper bounds on entanglement in a bipartite quantum system when only the reduced density matrices (marginals) are known. In particular, starting from the known two-qubit case, we propose a family of candidates for maximally entangled mixed states with respect to fixed marginals for two qutrits. These states are extremal in the convex set of two-qutrit states with fixed marginals. Moreover, it is shown that they are always quasidistillable. As a by-product we prove that any maximally correlated state that is quasidistillable must be pure. Our observations for two qutrits are supported by numerical analysis.
Baryogenesis from mixed particle decays
1996
We consider the $CP$ violating asymmetries produced in the decay of heavy particles, studying the effects of heavy particle mixing for arbitrary mass splittings. A considerable enhancement of the asymmetries is achieved when the masses of the mixed states are comparable, and the enhancement is maximal for mass splittings of the order of the widths of the decaying particles. We apply the results to the particular case of heavy scalar neutrino decays relevant for leptogenesis scenarios.
Interaction free and decoherence free states
2015
An interaction free evolving state of a closed bipartite system composed of two interacting subsystems is a generally mixed state evolving as if the interaction were a c-number. In this paper we find the characteristic equation of states possessing similar properties for a bipartite systems governed by a linear dynamical equation whose generator is sum of a free term and an interaction term. In particular in the case of a small system coupled to its environment, we deduce the characteristic equation of decoherence free states namely mixed states evolving as if the interaction term were effectively inactive. Several examples illustrate the applicability of our theory in different physical co…
Rydberg, valence and mixed states in the vertical spectrum of HF
2009
Abstract Size-consistent self-consistent multireference singles and doubles configuration interaction (SC)2–MR–SDCI, and linear response coupled cluster of singles and doubles including triples LR–CCSDR(3) methods, with a basis set of ANO’s augmented with a single series of molecular Rydberg functions, have been applied to the calculation of vertical excitation energies of HF in the 10–16 eV region. Special care has been put in the description of the valence, Rydberg and mixed states. Some advantage has been taken from the different physical contents of the methods to discuss some assignments. The (4,5) f Rydberg states of HF are predicted at 15.2 and 15.5 eV.