相关论文: Negative exchange interaction in Si quantum dot ar…

The presence of degenerate conduction band valleys and how they are mixed by interfaces play critical roles in determining electron interaction and spectrum in a silicon nanostructure. Here we investigate how the valley phases affect the…

It has been experimentally shown that negative exchange interactions can arise in a linear three-dot system when a two-electron double quantum dot is exchange coupled to a larger quantum dot containing on the order of one hundred electrons.…

Exchange coupling is a key ingredient for spin-based quantum technologies since it can be used to entangle spin qubits and create logical spin qubits. However, the influence of the electronic valley degree of freedom in silicon on exchange…

A two-dimensional electron gas (2DEG) in two-valley semiconductors has two discrete degrees of freedom given by the spin and valley quantum numbers. We analyze the zero-temperature magnetic instabilities of two-valley semiconductors with…

The effect of external electric field on the exchange interaction has been studied by an exact diagonalization method for two electrons in laterally coupled quantum dots (QD's). We have performed a systematic study of several nanodevices…

The rise of graphene opens a new door to qubit implementation, as discussed in the recent proposal of valley pair qubits in double quantum dots of gapped graphene (Wu et al., arXiv: 1104.0443 [cond-mat.mes-hall]). The work here presents the…

We study the exchange interaction between two hole-spin qubits in a double quantum dot setup in a silicon nanowire in the presence of magnetic and electric fields. Based on symmetry arguments we show that there exists an effective spin that…

A gate electric field has a small but non-negligible effect on the phase of the valley-orbit coupling in Si quantum dots. Finite interdot tunneling between valley eigenstates in a double quantum dot is enabled by a small difference in the…

Indirect exchange interaction between itinerant electrons and nano-structures with non-trivial geometrical configurations manifests a plethora of unexpected results. These configurations can be realized either in quantum dots with several…

We investigate a two-electron double quantum dot with both spin and valley degrees of freedom as they occur in graphene, carbon nanotubes, or silicon, and regard the 16-dimensional space with one electron per dot as a four-qubit logic…

We propose a scheme for implementing quantum gates and entanglement between spin qubits in the outer dots of a triple-dot system with an empty central dot. The voltage applied to the central dot can be tuned to realize the gate. Our scheme…

A parabolic quantum dot (QD) as realized by biasing nanostructured gates on bilayer graphene is investigated in the presence of electron-electron interaction. The energy spectrum and the phase diagram reveal unexpected transitions as…

We theoretically model the spin-orbit interaction in silicon quantum dot devices, relevant for quantum computation and spintronics. Our model is based on a modified effective mass approach with spin-valley boundary conditions, derived from…

We analyze the valley composition of one electron bound to a shallow donor close to a Si/barrier interface as a function of an applied electric field. A full six-valley effective mass model Hamiltonian is adopted. For low fields, the…

By operating a one-electron quantum dot (fabricated between a multielectron dot and a one-electron reference dot) as a spectroscopic probe, we study the spin properties of a gate-controlled multielectron GaAs quantum dot at the transition…

The valley-orbit coupling in a few-electron Si quantum dot is expected to be a function of its occupation number N. We study the spectrum of multivalley Si quantum dots for 2 <= N <= 4, showing that, counterintuitively, electron-electron…

Interactions between electrons can strongly affect the shape and functionality of multi-electron quantum dots. The resulting charge distributions can be localized, as in the case of Wigner molecules, with consequences for the energy…

With any roughness at the interface of an indirect-bandgap semiconducting dot, the phase of the valley-orbit coupling can take on a random value. This random value, in double quantum dots, causes a large change in the exchange splitting. We…

We consider a new quantum gate mechanism based on electron spins in coupled semiconductor quantum dots. Such gates provide a general source of spin entanglement and can be used for quantum computers. We determine the exchange coupling J in…

Spins in SiGe quantum dots are promising candidates for quantum bits but are also challenging due to the valley degeneracy which could potentially cause spin decoherence and weak spin-orbital coupling. In this work we demonstrate that…