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We carry out a quantum-mechanical analysis of a small Josephson junction coupled to a single-mode resonant cavity. We find that the eigenstates of the combined junction-cavity system are strongly entangled only when the gate voltage applied at one of the superconducting islands is tuned to certain special values. One such value corresponds to the resonant(More)
Bond stretching mimics different levels of electron correlation and provides a challenging test bed for approximate many-body computational methods. Using the recently developed phaseless auxiliary-field quantum Monte Carlo (AF QMC) method, we examine bond stretching in the well-studied molecules BH and N(2) and in the H(50) chain. To control the sign/phase(More)
We present an ab initio density functional study of ferroelectricity in single-domain PbTiO 3-based nanoca-pacitors. We used density functional theory with the recently introduced PBEsol generalized-gradient exchange-correlation functional, which we found to give accurate properties of bulk ferroelectric ͑FE͒ materials. Pt and Au electrodes are used in our(More)
We study the zero temperature (Tϭ0) quantum rotor model with on-site disorder in the charging energy. Such a model may serve as an idealized Hamiltonian for an array of Josephson-coupled small superconducting grains or superfluid 4 He in a disordered environment. In the approximation of small-amplitude phase fluctuations , the Hamiltonian maps onto a system(More)
Diffusion Monte Carlo (DMC) calculations are performed on the monocyclic and bicyclic forms of m-benzyne, which are the equilibrium structures at the CCSD(T) and CCSD levels of coupled cluster theory. We employed multiconfiguration self-consistent field trial wave functions which are constructed from a carefully selected eight-electrons-in-eight-orbitals(More)
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