369 research outputs found
Quantum gates by coupled quantum dots and measurement procedure in Si MOSFET
We investigated the quantum gates of coupled quantum dots, theoretically,
when charging effects can be observed. We have shown that the charged states in
the qubits can be observed by the channel current of the MOSFET structure.Comment: 3 pages, 2 figures, use revtex.sty. 'The Eleventh International
Conference on Nonequilibrium Carrier Dynamics in Semiconductors
(HCIS-11)',July 19-23, 199
The Effect of Local Structure and Non-uniformity on Decoherence-Free States of Charge Qubits
We analyze robustness of decoherence-free (DF) subspace in charge qubits when
there are a local structure and non-uniformity that violate collective
decoherence measurement condition. We solve master equations of up to four
charge qubits and a detector as two serially coupled quantum point contacts
(QPC) with an island structure. We show that robustness of DF states is
strongly affected by local structure as well as by non-uniformities of qubits
Steady-state solution for dark states using a three-level system in coupled quantum dots
Quantum dots (QDs) are one of the promising candidates of interconnection
between electromagnetic field and electrons in solid-state devices. Dark states
appear as a result of coherence between the electromagnetic fields and the
discrete energy levels of the system. Here, we theoretically solve the
steady-state solutions of the density matrix equations for a thee-level double
QD system and investigate the condition of the appearance of a dark state. We
also numerically show the appearance of the dark state by time-dependent
current characteristics.Comment: 5 pages, 5 figure
Superconductive Phonon Anomalies in High- Cuprates
We consider the effects on phonon dynamics of spin-lattice coupling within
the slave-boson mean-field treatment of the extended - model. With no
additional assumptions the theory is found to give a semi-quantitative account
of the frequency and linewidth anomalies observed by Raman and neutron
scattering for the 340 phonon mode in at the
superconducting transition. We discuss the applicability of the model to phonon
modes of different symmetries, and report a connection to spin-gap features
observed in underdoped YBCO. The results suggest the possibility of a unified
understanding of the anomalies in transport, magnetic and lattice properties.Comment: heavily revised version of previous paper, including systematic
treatment of effect of term, coupling constant derivation and calculation
of phonon linewidth broadening. Revised Figs. 3 and 4 still only available by
sending fax # to [email protected]
The Effect of Side Traps on Ballistic Transistor in Kondo Regime
The effect of side-traps on conductance is calculated in the range of
slave-boson mean field theory, especially when there are electrodes on both
sides of the conductor.
This corresponds to an investigation of transport properties in future
ballistic transistors. An intrinsic dip as a result of the interference effect
(Fano-Kondo effect) is expected to be observed as one of interesting interplays
between physics and engineering devices.Comment: 3 pages, 5 figures. 2006 International Conference on Solid State
Devices and Materials (SSDM2006), Sept. 12-15, 2006, Yokohama, Japa
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