Kehrein, Stefan K.

[["dc.bibliographiccitation.artnumber","094306"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","PHYSICAL REVIEW B"],["dc.bibliographiccitation.volume","88"],["dc.contributor.author","Medvedyeva, Mariya V."],["dc.contributor.author","Hoffmann, A. L."],["dc.contributor.author","Kehrein, Stefan"],["dc.date.accessioned","2018-11-07T09:19:52Z"],["dc.date.available","2018-11-07T09:19:52Z"],["dc.date.issued","2013"],["dc.description.abstract","We investigate how the Kondo screening cloud builds up as a function of space and time. Starting from an impurity spin decoupled from the conduction band, the Kondo coupling is switched on at time t = 0. We work at the Toulouse point where one can obtain exact analytical results for the ensuing spin dynamics at both zero and nonzero temperature T. For t > 0 the Kondo screening cloud starts building up in the wake of the impurity spin being transported to infinity. In this buildup process the impurity spin-conduction band spin susceptibility shows a sharp light cone due to causality, while the corresponding correlation function has a tail outside the light cone. At T = 0 this tail has a power-law decay as a function of distance from the impurity, which we interpret as due to initial entanglement in the Fermi sea."],["dc.identifier.doi","10.1103/PhysRevB.88.094306"],["dc.identifier.isi","000324485800002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/28743"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation.issn","1098-0121"],["dc.title","Spatiotemporal buildup of the Kondo screening cloud"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","205416"],["dc.bibliographiccitation.issue","20"],["dc.bibliographiccitation.journal","Physical Review. B"],["dc.bibliographiccitation.volume","91"],["dc.contributor.author","Medvedyeva, Mariya V."],["dc.contributor.author","Cubrovic, M. T."],["dc.contributor.author","Kehrein, Stefan"],["dc.date.accessioned","2018-11-07T09:57:15Z"],["dc.date.available","2018-11-07T09:57:15Z"],["dc.date.issued","2015"],["dc.description.abstract","We consider a quantum wire connected to the leads and subjected to dissipation along its length. The dissipation manifests as tunneling into (out of) the chain from (to) a memoryless environment. The evolution of the system is described by the Lindblad equation. Already infinitesimally small dissipation along the chain induces a quantum phase transition (QPT). This is a decoherence QPT: the reduced density matrix of a subsystem in the nonequilibrium steady state (far from the ends of the chain) can be represented as the tensor product of single-site density matrices. The QPT is identified from the jump of the current and the entropy per site as the dissipation becomes nonzero. We also explore the properties of the boundaries of the chain close to the transition point and observe that the boundaries behave as if they undergo a second-order phase transition as a function of the dissipation strength: the particle-particle correlation functions and the response to the electric field exhibit a power-law divergence. Disorder is known to localize one-dimensional systems, but the coupling to the memoryless environment pushes the system back into the delocalized state even in the presence of disorder. Interestingly, we observe a similar transition in the classical dissipative counterflow model: the current has a jump at the ends of the chain introducing an infinitely small dissipation."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [CRC SFB 1073, B03]"],["dc.identifier.doi","10.1103/PhysRevB.91.205416"],["dc.identifier.isi","000354548800003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37122"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation","SFB 1073: Kontrolle von Energiewandlung auf atomaren Skalen"],["dc.relation","SFB 1073 | Topical Area B | B03 Relaxation, Thermalisierung, Transport und Kondensation in hochangeregten Festkörpern"],["dc.relation.issn","2469-9969"],["dc.relation.issn","2469-9950"],["dc.title","Dissipation-induced first-order decoherence phase transition in a noninteracting fermionic system"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","205410"],["dc.bibliographiccitation.issue","20"],["dc.bibliographiccitation.journal","Physical Review. B"],["dc.bibliographiccitation.volume","90"],["dc.contributor.author","Medvedyeva, Mariya V."],["dc.contributor.author","Kehrein, Stefan"],["dc.date.accessioned","2018-11-07T09:32:41Z"],["dc.date.available","2018-11-07T09:32:41Z"],["dc.date.issued","2014"],["dc.description.abstract","We address the question of how a nonequilibrium steady state (NESS) is reached in the Lindbladian dynamics of an open quantum system. We develop an expansion of the density matrix in terms of the NESS excitations, each of which has its own (exponential) decay rate. However, when the decay rates tend to zero for many NESS excitations (the spectral gap of the Liouvillian is closed in the thermodynamic limit), the long-time dynamics of the system can exhibit a power-law behavior. This relaxation to NESS expectation values is determined by the density of states close to zero spectral gap and the value of the operator in these states. We illustrate this main idea on the example of the lattice of noninteracting fermions coupled to Markovian leads at infinite bias voltage. The current comes towards its NESS value starting from a typical initial state as tau(-3/2). This behavior is universal and independent of the space dimension."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [SFB 1073, B03]"],["dc.identifier.doi","10.1103/PhysRevB.90.205410"],["dc.identifier.isi","000345466000006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/31801"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation","SFB 1073: Kontrolle von Energiewandlung auf atomaren Skalen"],["dc.relation","SFB 1073 | Topical Area B | B03 Relaxation, Thermalisierung, Transport und Kondensation in hochangeregten Festkörpern"],["dc.relation.issn","1550-235X"],["dc.relation.issn","1098-0121"],["dc.title","Power-law approach to steady state in open lattices of noninteracting electrons"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]