Size-evolutions of structural and spectral properties in two types of finite systems are discussed. First we focus on energetics and structures of gold clusters, particularly AuN in the 40.N . 200 range exhibiting a discrete sequence of optimal clusters with a decahedral structural motiff, and on the electronic structure of bare and methyl-thiol passivated Au38 clusters. Subsequently, bonding a...

Colloidal quantum dots offer broad tuning of semiconductor band structure via the quantum size effect. In this paper, we present a detailed investigation on the influence of the thickness of colloidal lead sulfide (PbS) nanocrystals (active layer) to the photovoltaic performance of colloidal quantum dot solar cells. The PbS nanocrystals (QDs) were synthesized in a non-coordinating solvent, 1-oc...

A simple expression to compute the quantum discord between two orbitals in fermion systems is derived using parity superselection rule. As correlation depends on basis chosen, we discuss a special orbital basis, natural one. We show that correlations pairs disappear when pairing tensor zero, i.e., particle number symmetry preserved. The Hartree-Fock within Slater determinant state, Hartree-Fock...

We investigate current fluctuations in a three-terminal quantum dot in the sequential tunneling regime. In the voltage-bias configuration chosen here, the circuit is operated as a beam splitter, i.e., one lead is used as an input and the other two as outputs. In the limit where a double occupancy of the dot is not possible, a super-Poissonian Fano factor of the current in the input lead and pos...

We consider theoretically 13C-hyperfine interaction-induced dephasing in carbon nanotubes double quantum dots with curvature-induced spin-orbit coupling. For two electrons initially occupying a single dot, we calculate the average return probability after separation into the two dots, which have random nuclear spin configurations. We focus on the long-time saturation value of the return probabi...

The spin of an electron placed in a magnetic field provides a natural twolevel system suitable as a qubit in a quantum computer [1]. In this work, we describe the experimental steps we have taken towards using a single electron spin, trapped in a semiconductor quantum dot, as such a spin qubit [2]. The outline is as follows. Section 1 serves as an introduction into quantum computing and quantum...

We perform measurements on an AlGaAs/GaAs double-quantum-dot structure, where dots are separated by an opaque barrier and each dot conductance is measured independently and simultaneously. We measure the Coulomb blockade oscillations ~CBOs! for each dot when the structure is configured for one and two dots. When configured as a single-dot device, we sweep the backgate and observe different CBO ...

Achieving control over the electron spin in quantum dots (artificial atoms) or real atoms promises access to new technologies in conventional and quantum information processing. Here we review our proposal for quantum computing with the spins of electrons confined to quantum dots. We discuss the basic requirements for implementing spin qubits, and describe a complete set of quantum gates for si...

We propose an experimental scheme to implement a strong photon blockade with a single quantum dot coupled to a nanocavity. The photon blockade effect can be tremendously enhanced by driving the cavity and the quantum dot simultaneously with two classical laser fields. This enhancement of photon blockade is ascribed to the quantum interference effect to avoid two-photon excitation of the cavity ...

Universal multiple-qubit gates can be implemented by a set of universal single-qubit gates and any one kind of entangling two-qubit gate, such as a controlled-NOT gate. For semiconductor quantum dot qubits, two-qubit gate operations have so far only been demonstrated in individual electron spin-based quantum dot systems. Here we demonstrate the conditional rotation of two capacitively coupled c...