Quantum information processing in solid states: A critique of two-level approximation
Realizing Controllable Quantum States: Mesoscopic Superconductivity and Spintronics - In the Light of Quantum Computation
World Scientific Publishing Co.
233 - 240
Item Usage Stats
MetadataShow full item record
We 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.
Macroscopic quantum coherence
Published Version (Please cite this version)http://dx.doi.org/10.1142/9789812701619_0036
Showing items related by title, author, creator and subject.
Navascués, M.; Vértesi, T. (American Physical Society, 2015)We describe a simple method to derive high performance semidefinite programing relaxations for optimizations over complex and real operator algebras in finite dimensional Hilbert spaces. The method is very flexible, easy ...
Electroluminescence efficiency enhancement in quantum dot light-emitting diodes by embedding a silver nanoisland layer Yang, X.; Hernandez-Martinez, P. L.; Dang C.; Mutlugün, E.; Zhang, K.; Demir, Hilmi Volkan; Sun X. W. (Wiley-VCH Verlag, 2015)A colloidal quantum dot light-emitting diode (QLED) is reported with substantially enhanced electroluminescence by embedding a thin layer of Ag nanoislands into hole transport layer. The maximum external quantum efficiency ...
Özel, Tuncay; Sarı, Emra; Nizamoğlu, Sedat; Demir, Hilmi Volkan (SPIE, 2007)We present a novel dual-operation InGaN/GaN based quantum optoelectronic device (QOD) that operates as a quantum electroabsorption modulator in reverse bias and as a light emitter in forward bias in the spectral range of ...