Quantum information processing in solid states: A critique of two-level approximation

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dc.citation.epage240en_US
dc.citation.spage233en_US
dc.contributor.authorSavran K.en_US
dc.contributor.authorHakioğlu T.en_US
dc.date.accessioned2018-04-12T13:38:35Z
dc.date.available2018-04-12T13:38:35Z
dc.date.issued2005en_US
dc.departmentDepartment of Physicsen_US
dc.description.abstractWe examine the effect of multilevels on decoherence and dephasing properties of a quantum system consisting of a non-ideal two level subspace, identified as the qubit and a finite set of higher energy levels above this qubit subspace. The whole system is under interaction with an environmental bath through a Caldeira-Leggett type coupling. The model that we use is an rf-SQUID under macroscopic quantum coherence and coupled inductively to a flux noise characterized by an environmental spectrum. The model interaction can generate dipole couplings which can be appreciable for a number of high levels. The decoherence properties of the qubit subspace is examined numerically using the master equation formalism of the system’s reduced density matrix. We numerically examine the relaxation and dephasing times as the environmental frequency spectrum, and the multilevel system parameters are varied at zero temperature. We observe that, these time scales receive contribution from all available energies in the noise spectrum (even well above the system’s energy scales) stressing the dominant role played by the non-resonant (virtual) transitions. The relaxation and dephasing times calculated, strongly depend on the number of levels within the range of levels for which appreciable couplings are produced. Under the influence of these effects, we remark that the validity of the two level approximation is restricted not by the temperature but by these dipole couplings as well as the availability of the environmental modes at low temperatures. © 2005 by World Scientific Publishing Co. Pte. Ltd.en_US
dc.description.provenanceMade available in DSpace on 2018-04-12T13:38:35Z (GMT). No. of bitstreams: 1 bilkent-research-paper.pdf: 179475 bytes, checksum: ea0bedeb05ac9ccfb983c327e155f0c2 (MD5) Previous issue date: 2005en
dc.identifier.doi10.1142/9789812701619_0036en_US
dc.identifier.isbn9789812701619
dc.identifier.isbn9789812564689
dc.identifier.urihttp://hdl.handle.net/11693/37825
dc.language.isoEnglishen_US
dc.publisherWorld Scientific Publishing Co.en_US
dc.relation.isversionofhttp://dx.doi.org/10.1142/9789812701619_0036en_US
dc.source.titleRealizing Controllable Quantum States: Mesoscopic Superconductivity and Spintronics - In the Light of Quantum Computationen_US
dc.subjectCouplingsen_US
dc.subjectElectromagnetic inductionen_US
dc.subjectQuantum computersen_US
dc.subjectQuantum opticsen_US
dc.subjectSQUIDsen_US
dc.subjectDecoherence propertiesen_US
dc.subjectMacroscopic quantum coherenceen_US
dc.subjectModel interactionen_US
dc.subjectMulti-level systemsen_US
dc.subjectQuantum-information processingen_US
dc.subjectReduced-density matrixen_US
dc.subjectTwo-level approximationen_US
dc.subjectZero temperaturesen_US
dc.subjectQuantum theoryen_US
dc.titleQuantum information processing in solid states: A critique of two-level approximationen_US
dc.typeBook Chapteren_US

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