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A new approach to the implementation of certain logical functions in quantum-dot gates for single-electron computing is proposed.
It is shown that placing a gate in a uniform external magnetic field allows one to construct gates with 1) symmetric physical
truth tables and 2) large (in some cases close to saturated) absolute magnitude of the average spin at the output dots. Thus
two serious obstacles are removed which otherwise could present a problem in the fabrication of a set of coupled quantum-dot
gates.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 3, 214–218 (10 August 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
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We investigate the effect of Zeeman splitting on quasiparticle transport in normal-superconducting-normal (NSN) aluminum single-electron transistors (SETs). In the above-gap transport, the interplay of Coulomb blockade and Zeeman splitting leads to spin-dependence of the sequential tunneling. This creates regimes where either one or both spin species can tunnel onto or off the island. At lower biases, spin-dependence of the single quasiparticle state is studied, and operation of the device as a bipolar spin filter is suggested. 相似文献
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A. Brataas Yu.V. Nazarov J. Inoue G.E.W. Bauer 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):421-430
We study transport in ferromagnetic single-electron transistors. The non-equilibrium spin accumulation on the island caused
by a finite current through the system is described by a generalized theory of the Coulomb blockade. It enhances the tunnel
magnetoresistance and has a drastic effect on the time-dependent transport properties. A transient decay of the spin accumulation
may reverse the electric current on time scales of the order of the spin-flip relaxation time. This can be used as an experimental
signature of the non-equilibrium spin accumulation.
Received 6 May 1998 相似文献
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Shunsuke UenoYusuke Tomoda Watari KumeMichinobu Hanada Kazutoshi TakiyaJun-ichi Shirakashi 《Applied Surface Science》2012,258(6):2153-2156
We report a simple and easy method for the integration of planar-type single-electron transistors (SETs). This method is based on electromigration induced by a field emission current, which is so-called “activation”. The integration of two SETs was achieved by performing the activation to the series-connected initial nanogaps. In both simultaneously activated devices, current-voltage (ID-VD) curves displayed Coulomb blockade properties, and Coulomb blockade voltage was also obviously modulated by the gate voltage at 16 K. Moreover, the charging energy of both SETs was well controlled by the preset current in the activation. 相似文献
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A simple method, based on the proximity effect of electron beam lithography, alleviated by exposing various shapes in the
pattern of incident electron exposures with various intensities, was applied to fabricate silicon point-contact devices. The
drain current (I
d) of the device oscillates against gate voltage. The electrical characteristics of the single-electron transistor were observed
to be consistent with the expected behavior of electron transport through gated quantum dots, up to 150 K. The dependence
of the electrical characteristics on the dot size reveals that the I
d oscillation follows from the Coulomb blockade by poly-Si grains in the poly-Si dot. The method of fabrication of this device
is completely compatible with complementary metal-oxide-semiconductor technology, raising the possibility of manufacturing
large-scale integrated nanoelectronic systems. 相似文献
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Kogan A Amasha S Goldhaber-Gordon D Granger G Kastner MA Shtrikman H 《Physical review letters》2004,93(16):166602
We measure the spin splitting in a magnetic field B of localized states in single-electron transistors using a new method, inelastic spin-flip cotunneling. Because it involves only internal excitations, this technique gives the most precise value of the Zeeman energy Delta=/g/mu(B)B. In the same devices we also measure the splitting with B of the Kondo peak in differential conductance. The Kondo splitting appears only above a threshold field as predicted by theory. However, the magnitude of the Kondo splitting at high fields exceeds 2/g/mu(B)B in disagreement with theory. 相似文献
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Jan Martinek Jzef Barna Sadamichi Maekawa Herbert Schoeller Gerd Schn 《Journal of magnetism and magnetic materials》2002,240(1-3):143-145
Electron tunneling through small metallic particles (islands) coupled to two ferromagnetic electrodes is studied theoretically in the Coulomb blockade regime, where higher order tunneling processes play a significant role. Transport characteristics of the system are analyzed by the real-time diagrammatic technique. It is shown that the spin splitting of the electrochemical potential due to spin accumulation on the island should be detectable from the spacing between two resonances in the current–voltage characteristics. 相似文献
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Spin dependent transport in a ferromagnet-superconductor single-electron transistor is studied theoretically taking into account spin accumulation, spin relaxation, gap suppression, and charging effects. A strong dependence of the gap on the magnetic state of the electrodes is found, which gives rise to a magnetoresistance of up to 100%. We predict that fluctuations of the spin accumulation can play such an important role as to cause the island to fluctuate between the superconducting and normal states. Furthermore, the device exhibits a nearly complete gate-controlled spin-valve effect. 相似文献
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We have investigated the effects of quantum fluctuations of quasiparticles on the operation of superconducting radio-frequency single-electron transistors (rf-SETs) for large values of the quasiparticle cotunneling parameter alpha = 8EJ/Ec, where EJ and Ec are the Josephson and charging energies. We find that, for alpha > 1, subgap rf-SET operation is still feasible despite quantum fluctuations that wash out quasiparticle tunneling thresholds. Surprisingly, such rf-SETs show linearity and signal-to-noise ratio superior to those obtained when quantum fluctuations are weak, while still demonstrating excellent charge sensitivity. 相似文献
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We propose a cyclic refrigeration principle based on mesoscopic electron transport. Synchronous sequential tunneling of electrons in a Coulomb-blockaded device, a normal metal-superconductor single-electron box, results in a cooling power of approximately k(B)T x f at temperature T over a wide range of cycle frequencies f. Electrostatic work, done by the gate voltage source, removes heat from the Coulomb island with an efficiency of approximately k(B)T/Delta, where Delta is the superconducting gap parameter. The performance is not affected significantly by nonidealities, for instance by offset charges. We propose ways of characterizing the system and of its practical implementation. 相似文献
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We demonstrate a sensitive method of charge detection based on radio-frequency readout of the Josephson inductance of a superconducting single-electron transistor. Charge sensitivity 1.4 x 10(-4) e/square root Hz, limited by a preamplifier, is achieved in an operation mode which takes advantage of the nonlinearity of the Josephson potential. Owing to reactive readout, our setup has more than 2 orders of magnitude lower dissipation than the existing method of radio-frequency electrometry. With an optimized sample, we expect uncoupled energy sensitivity below variant Planck's over h in the same experimental scheme. 相似文献
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《Superlattices and Microstructures》2000,27(5-6):617-620
We consider the continuum limit of the standard model for treating single-electron tunneling (SET) of electrons through a one-dimensional array of tunnel junctions. We show that the formalism reduces to the computation of the motion of overdamped particles undergoing potential gradient flow, with the potential being given by the full interacting free energy of the electrons in the system. We show that the tunneling coefficients in the SET model can be re-interpreted in terms of a diffusion coefficient and a temperature and that therefore the SET problem reduces to a fully self-consistent treatment of overdamped particle diffusion. 相似文献
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A modified spin-flip model is used to investigate the stability of optically-pumped quantum-dot spin-vertical cavity surface-emitting lasers. in terms of pump intensity and polarization. The stability maps exhibit pronounced polarization switching in the stable regions. Periodic oscillations in unstable regions are attributed to competition between spin relaxation and birefringence. 相似文献
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