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We study the Kondo effect in the electron transport through a quantum dot coupled to ferromagnetic leads, using a real-time diagrammatic technique which provides a systematic description of the nonequilibrium dynamics of a system with…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yasuhiro Utsumi , Jan Martinek , Gerd Schön , Hiroshi Imamura , Sadamichi Maekawa

At temperatures below the magnetic anisotropy energy, monodomain magnetic systems (small particles, nanomagnetic devices, etc.) must relax quantum mechanically. This quantum relaxation must be mediated by the coupling to both nuclear spins…

Condensed Matter · Physics 2009-10-28 N. V. Prokof'ev , P. C. E. Stamp

We calculate analytically the exact dynamical response of a droplet of N interacting electrons in a quantum dot with an arbitrarily time-dependent parabolic confinement potential \omega(t) and a perpendicular magnetic field. We find that,…

Condensed Matter · Physics 2016-08-31 Simon C. Benjamin , Neil F. Johnson

The degree of entanglement of an electron with a hole in a vertically coupled self-assembled dot molecule is shown to be tunable by an external electric field. Using atomistic pseudopotential calculations followed by a configuration…

Materials Science · Physics 2009-11-11 Gabriel Bester , Alex Zunger

Non-equilibrium spin transport through an interacting quantum dot is analyzed. The coherent spin oscillations in the dot provide a generating source for spin current. In the interacting regime, the Kondo effect is influenced in a…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Ping Zhang , Qi-Kun Xue , X. C. Xie

The spin of an electron trapped in a quantum dot is a promising candidate implementation of a qubit for quantum information processing. We study the central spin problem of the effect of the hyperfine interaction between such an electron…

Mesoscale and Nanoscale Physics · Physics 2007-08-29 Gang Chen , Doron L. Bergman , Leon Balents

We use frequency-dependent capacitance-voltage spectroscopy to measure the tunneling probability into self-assembled InAs quantum dots. Using an in-plane magnetic field of variable strength and orientation, we are able to obtain information…

Other Condensed Matter · Physics 2009-11-10 Oliver S. Wibbelhoff , Axel Lorke , Dirk Reuter , Andreas D. Wieck

Properties of the "electron gas" - in which conduction electrons interact by means of Coulomb forces but ionic potentials are neglected - change dramatically depending on the balance between kinetic energy and Coulomb repulsion. The limits…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Amit Ghosal , A. D. Guclu , C. J. Umrigar , Denis Ullmo , Harold U. Baranger

Controlling electron spins strongly coupled to magnetic and nuclear spins in solid state systems is an important challenege in the field of spintronics and quantum computation. We show here that electron droplets with no net spin in…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 Ramin M. Abolfath , Marek Korkusinski , Thomas Brabec , Pawel Hawrylak

The confinement mechanism of electrons in gated circular quantum dots is studied in a sequence of models, from self-consistent 3D Hartree calculations to the semiclassical model of Shikin et al. Separation of the vertical from transverse…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. Martorell , D. W. L. Sprung

One-electron tunneling through a quantum dot with a strong magnetic field in the direction of the current is studied. The linear magneto-conductance is computed for a model parabolic dot with seven electrons in the intermediate states and…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Augusto Gonzalez , Roberto Capote

The total energy of a quasi-one-dimensional electron system is calculated using density functional theory. It is shown that spontaneous ferromagnetic state in quantum wire occurs at low one-dimensional electron density. The critical…

Mesoscale and Nanoscale Physics · Physics 2013-01-14 A. A. Vasilchenko

We have studied the electron spin coherence in an ensemble of positively charged InAs/GaAs quantum dots. In a transverse magnetic field, we show that two main contributions must be taken into account to explain the damping of the circular…

Materials Science · Physics 2009-11-13 L. Lombez , P. -F. Braun , X. Marie , P. Renucci , B. Urbaszek , T. Amand , O. Krebs , P. Voisin

We show that the spins of all electrons, each confined in a quantum dot of an (In,Ga)As/GaAs dot ensemble, can be driven into a single mode of precession about a magnetic field. This regime is achieved by allowing only a single mode within…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 A. Greilich , S. Spatzek , I. A. Yugova , I. A. Akimov , D. R. Yakovlev , Al. L. Efros , D. Reuter , A. D. Wieck , M. Bayer

We study two-dimensional quantum dots using the variational quantum Monte Carlo technique in the weak-confinement limit where the system approaches the Wigner molecule, i.e., the classical solution of point charges in an external potential.…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 A. Harju , S. Siljamäki , R. M. Nieminen

Spatially nonhomogeneously spin polarized nuclei are proposed as a new mechanism to monitor electron states in a nanostructure, or as a means to createn and, if necessary, reshape such nanostructures in the course of the experiment. We…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 V. Fleurov , V. A. Ivanov , F. M. Peeters , I. D. Vagner

The main source of decoherence for an electron spin confined to a quantum dot is the hyperfine interaction with nuclear spins. To analyze this process theoretically we diagonalize the central spin Hamiltonian in the high magnetic B-field…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Oleksandr Tsyplyatyev , Daniel Loss

Semiconductor quantum dots provide a spin-coupled system of an electron and nuclei via enhanced hyperfine interaction. We showed that the nuclear spin polarization in single quantum dots can have three stable branches under a longitudinal…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Sota Yamamoto , Reina Kaji , Hirotaka Sasakura , Satoru Adachi

We consider circular and elliptic quantum dots with parabolic external confinement, containing 0 - 22 electrons and with values of r_s in the range 0 < r_s < 3. We perform restricted and unrestricted Hartree-Fock calculations, and further…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Clare Sloggett , Oleg Sushkov

A number of methods are discussed which may serve for a treatment of electron correlations in solids. When the electron correlations are relatively weak like in semiconductors or a number of ionic crystals one may start from a…

Condensed Matter · Physics 2007-05-23 Prof. Dr. Peter Fulde
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