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Similar to atoms and nuclei, semiconductor quantum dots exhibit formation of shells. Predictions of magnetic behavior of the dots are often based on the shell occupancies. Thus, closed-shell quantum dots are assumed to be inherently…

Mesoscale and Nanoscale Physics · Physics 2011-06-14 R. Oszwałdowski , I. Žutić , A. G. Petukhov

We address a recent theoretical discrepancy concerning the Kondo effect in quantum dots with an even number of electrons where spin-singlet and -triplet states are nearly degenerate. We show that the discrepancy arises from the fact that…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Mikio Eto , Yuli V. Nazarov

Spin properties of single electron states in laterally coupled quantum dots in the presence of a perpendicular magnetic field are studied by exact numerical diagonalization. Dresselhaus (linear and cubic) and Bychkov-Rashba spin-orbit…

Other Condensed Matter · Physics 2007-05-23 Peter Stano , Jaroslav Fabian

The $s_z=0$ spin configuration of two electrons confined at a double quantum dot (DQD) encodes the singlet-triplet qubit (STQ). We introduce the inverted STQ (ISTQ) that emerges from the setup of two quantum dots (QDs) differing…

Mesoscale and Nanoscale Physics · Physics 2014-11-27 Sebastian Mehl , David P. DiVincenzo

The ground states of few electrons confined in two vertically coupled quantum rings in the presence of an external magnetic field are studied systematically within the current spin-density functional theory. Electron-electron interactions…

Mesoscale and Nanoscale Physics · Physics 2009-10-05 L. K. Castelano , G. -Q. Hai , B. Partoens , F. M. Peeters

We consider two interacting electrons in a semiconductor quantum dot structure which consists of a small dot within a larger dot, and demonstrate a singlet-triplet filtering mechanism which involves spin-dependent resonances and can…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 G. Giavaras , J. H. Jefferson , M. Fearn , C. J. Lambert

We consider the motion of electrons confined to a two dimensional plane with an externally applied perpendicular inhomogeneous magnetic field, both with and without a Coulomb potential. We find that as long as the magnetic field is…

Mesoscale and Nanoscale Physics · Physics 2016-08-05 C. A. Downing , M. E. Portnoi

We report measurements of the spin susceptibility in dilute two-dimensional electrons confined to a 45$\AA$ wide AlAs quantum well. The electrons in this well occupy an out-of-plane conduction-band valley, rendering a system similar to…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 K. Vakili , Y. P. Shkolnikov , E. Tutuc , E. P. De Poortere , M. Shayegan

An atomistic model based on the Keating potential and the conjugate gradient method are used for simulation of the strain fields for single Ge/Si quantum dots. Calculations are performed in the cluster approximation using clusters…

Mesoscale and Nanoscale Physics · Physics 2016-01-20 Yu. N. Morokov , M. P. Fedoruk

The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of…

Quantum dots can confine single electrons or holes to define spin qubits that can be operated with high fidelity. Experimental work has progressed from linear to two-dimensional arrays of quantum dots, enabling qubit interactions that are…

We demonstrate double quantum dots fabricated in undoped Si/SiGe heterostructures relying on a double top-gated design. Charge sensing shows that we can reliably deplete these devices to zero charge occupancy. Measurements and simulations…

A system of two quantum wells (QW), one made of HgCdTe and the other of HgCdMnTe, subjected to electric and magnetic fields $F$ and $B$ parallel to the growth direction, is proposed and described theoretically. It is shown that in such a…

Materials Science · Physics 2012-06-21 Pawel Pfeffer , Wlodek Zawadzki

The spin dynamics in two electron double quantum dots embedded in two dimensional electron gas at the interface between SrTiO$_3$ and LaAlO$_3$ is studied by an exact numerical solution of the time-dependent Schr\"odinger equation, in the…

Mesoscale and Nanoscale Physics · Physics 2024-09-13 B. Szafran , M. Zegrodnik , M. P. Nowak , R. Citro , P. Wojcik

We propose an implementation of a singlet-only spin qubit in a GaAs-based triple quantum dot with a (1,4,1) charge occupation. In the central multi-electron dot, the interplay between Coulomb interaction and an out-of-plane magnetic field…

Mesoscale and Nanoscale Physics · Physics 2020-03-18 Arnau Sala , Jørgen Holme Qvist , Jeroen Danon

We successfully demonstrated experimentally the electrical-field-mediated control of the spin of electrons confined in an SOI Quantum Dot (QD) device fabricated with a standard CMOS process flow. Furthermore, we show that the Back-Gate…

Single-electron occupation is an essential component to measurement and manipulation of spin in quantum dots, capabilities that are important for quantum information processing. Si/SiGe is of interest for semiconductor spin qubits, but…

We quantify the contributions of hyperfine and spin-orbit mediated singlet-triplet mixing in weakly coupled InAs quantum dots by electron transport spectroscopy in the Pauli spin blockade regime. In contrast to double dots in GaAs, the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 A. Pfund , I. Shorubalko , K. Ensslin , R. Leturcq

Electrical transport in double quantum dots (DQDs) illuminates many interesting features of the dots' carrier states. Recent advances in silicon quantum information technologies have renewed interest in the valley states of electrons…

Mesoscale and Nanoscale Physics · Physics 2017-11-15 Justin K. Perron , Michael J. Gullans , Jacob M. Taylor , M. D. Stewart, , Neil M. Zimmerman

We present experimental data and associated theory for correlations in a series of experiments involving repeated Landau-Zener sweeps through the crossing point of a singlet state and a spin aligned triplet state in a GaAs double quantum…