Physikhttp://kops.uni-konstanz.de:80/handle/123456789/412018-11-21T21:04:41Z2018-11-21T21:04:41ZPeriodic Fock exchange with atom-centered Gaussian basis setsIrmler, Andreaspop244040123456789/439332018-11-21T10:00:28Z2018Periodic Fock exchange with atom-centered Gaussian basis sets
Irmler, Andreas
2018Irmler, Andreas530DOCTORAL_THESISurn:nbn:de:bsz:352-2-1ufj0nn454qjh9eng2018-11-21T10:55:11+01:00123456789/412018-11-21T09:55:11ZDecoherence in the quantum Ising model with transverse dissipative interaction in strong-coupling regimeWeisbrich, Hannespop238906Saussol, CyrilBelzig, Wolfgangpop137343Rastelli, Gianlucapop242135123456789/42145.22018-11-14T02:04:19Z2018-04-20T11:43:13ZDecoherence in the quantum Ising model with transverse dissipative interaction in strong-coupling regime
Weisbrich, Hannes; Saussol, Cyril; Belzig, Wolfgang; Rastelli, Gianluca
We study the decoherence dynamics of a quantum Ising lattice of finite size with a transverse dissipative interaction, namely, the coupling with the bath is assumed perpendicular to the direction of the spins interaction and parallel to the external magnetic field. In the limit of small transverse field, the eigenstates and spectrum are obtained by a strong-coupling expansion, from which we derive the Lindblad equation in the Markovian limit. At temperature lower than the energy gap and for weak dissipation, the decoherence dynamics can be restricted to take only the two degenerate ground states and the first excited subspace into account. The latter is formed by pairs of topological excitations (domain walls or kinks), which are quantum delocalized along the chain due to the small magnetic field. We find that some of these excited states form a relaxation-free subspace, namely, they do not decay to the ground states.
2018-04-20T11:43:13ZWeisbrich, HannesSaussol, CyrilBelzig, WolfgangRastelli, Gianluca530We study the decoherence dynamics of a quantum Ising lattice of finite size with a transverse dissipative interaction, namely, the coupling with the bath is assumed perpendicular to the direction of the spins interaction and parallel to the external magnetic field. In the limit of small transverse field, the eigenstates and spectrum are obtained by a strong-coupling expansion, from which we derive the Lindblad equation in the Markovian limit. At temperature lower than the energy gap and for weak dissipation, the decoherence dynamics can be restricted to take only the two degenerate ground states and the first excited subspace into account. The latter is formed by pairs of topological excitations (domain walls or kinks), which are quantum delocalized along the chain due to the small magnetic field. We find that some of these excited states form a relaxation-free subspace, namely, they do not decay to the ground states.JOURNAL_ARTICLEurn:nbn:de:bsz:352-2-15bi3in3xqt3z4eng10.1103/PhysRevA.98.0521091050-29472469-9934985Physical Review A2018-11-12T12:57:45+01:00123456789/41Physical Review A ; 98 (2018), 5. - 052109. - ISSN 1050-2947. - eISSN 2469-9934true2018-11-12T11:57:45ZRheology of Inelastic Hard Spheres at Finite Density and Shear RateKranz, W. TillFrahsa, Fabianpop226117Zippelius, AnnetteFuchs, Matthiaspop52953Sperl, Matthias123456789/437232018-11-09T02:14:47Z2018Rheology of Inelastic Hard Spheres at Finite Density and Shear Rate
Kranz, W. Till; Frahsa, Fabian; Zippelius, Annette; Fuchs, Matthias; Sperl, Matthias
Considering a granular fluid of inelastic smooth hard spheres, we discuss the conditions delineating the rheological regimes comprising Newtonian, Bagnoldian, shear thinning, and shear thickening behavior. Developing a kinetic theory, valid at finite shear rates and densities around the glass transition density, we predict the viscosity and Bagnold coefficient at practically relevant values of the control parameters. The determination of full flow curves relating the shear stress σ to the shear rate ˙γ and predictions of the yield stress complete our discussion of granular rheology derived from first principles.
2018Kranz, W. TillFrahsa, FabianZippelius, AnnetteFuchs, MatthiasSperl, Matthias530Considering a granular fluid of inelastic smooth hard spheres, we discuss the conditions delineating the rheological regimes comprising Newtonian, Bagnoldian, shear thinning, and shear thickening behavior. Developing a kinetic theory, valid at finite shear rates and densities around the glass transition density, we predict the viscosity and Bagnold coefficient at practically relevant values of the control parameters. The determination of full flow curves relating the shear stress σ to the shear rate ˙γ and predictions of the yield stress complete our discussion of granular rheology derived from first principles.JOURNAL_ARTICLEurn:nbn:de:bsz:352-2-w0olmyz06l299eng10.1103/PhysRevLett.121.1480020031-90071079-711412114Physical Review Letters2018-11-08T10:00:53+01:00123456789/41Physical Review Letters ; 121 (2018), 14. - 148002. - ISSN 0031-9007. - eISSN 1079-7114true2018-11-08T09:00:53ZQuadrupolar Exchange-Only Spin QubitRuss, Maximilianpop222304Petta, Jason R.Burkard, Guidopop205895123456789/436942018-11-08T02:14:49Z2018-07-27T07:55:25ZQuadrupolar Exchange-Only Spin Qubit
Russ, Maximilian; Petta, Jason R.; Burkard, Guido
We propose a quadrupolar exchange-only spin qubit that is highly robust against charge noise and nuclear spin dephasing, the dominant decoherence mechanisms in quantum dots. The qubit consists of four electrons trapped in three quantum dots, and operates in a decoherence-free subspace to mitigate dephasing due to nuclear spins. To reduce sensitivity to charge noise, the qubit can be completely operated at an extended charge noise sweet spot that is first-order insensitive to electrical fluctuations. Because of on-site exchange mediated by the Coulomb interaction, the qubit energy splitting is electrically controllable and can amount to several GHz even in the “off” configuration, making it compatible with conventional microwave cavities.
2018-07-27T07:55:25ZRuss, MaximilianPetta, Jason R.Burkard, Guido530We propose a quadrupolar exchange-only spin qubit that is highly robust against charge noise and nuclear spin dephasing, the dominant decoherence mechanisms in quantum dots. The qubit consists of four electrons trapped in three quantum dots, and operates in a decoherence-free subspace to mitigate dephasing due to nuclear spins. To reduce sensitivity to charge noise, the qubit can be completely operated at an extended charge noise sweet spot that is first-order insensitive to electrical fluctuations. Because of on-site exchange mediated by the Coulomb interaction, the qubit energy splitting is electrically controllable and can amount to several GHz even in the “off” configuration, making it compatible with conventional microwave cavities.JOURNAL_ARTICLEeng10.1103/PhysRevLett.121.1777010031-90071079-711412117Physical Review Letters2018-11-07T08:52:58+01:00123456789/41Physical Review Letters ; 121 (2018), 17. - 177701. - ISSN 0031-9007. - eISSN 1079-7114true2018-11-07T07:52:58Ztrue