Effect of confinement potential geometry on entanglement in quantum dot-based nanostructures

Abstract

We calculate the spatial entanglement between two electrons trapped in a nanostructure for a broad class of confinement potentials, including single and double quantum dots, and core-shell quantum dot structures. By using a parametrized confinement potential, we are able to switch from one structure to the others with continuity and to analyze how the entanglement is influenced by the changes in the confinement geometry. We calculate the many-body wave function by 'exact' diagonalization of the time independent Schrödinger equation. We discuss the relationship between the entanglement and specific cuts of the wave function, and show that the wave function at a single highly symmetric point could be a good indicator for the entanglement content of the system. We analyze the counterintuitive relationship between spatial entanglement and Coulomb interaction, which connects maxima (minima) of the first to minima (maxima) of the latter. We introduce a potential quantum phase transition which relates quantum states characterized by different spatial topology. Finally we show that by varying shape, range and strength of the confinement potential, it is possible to induce strong and rapid variations of the entanglement between the two electrons. This property may be used to tailor nanostructures according to the level of entanglement required by a specific application.

Photoluminescence of CuInS 2 nanocrystals: effect of surface modification

“…It is known that band gap of nanocrystals can be shifted by the lattice stress originated from the lattice mismatch between core and shell layers. [14] Since ZnS with a smaller lattice parameter than CuInS2 can give rise to a compressive stress on CIS cores and the band gap deformation potential (dEg/dlnV) is negative, it is quite natural to expect shift to a smaller wavelength or blueshift in PL spectra after ZnS capping on CIS NCs. In contrast to this, formation of alloyed capping layer, (Cd,Zn)S shifted the XRD profile to a lower angle, which indicates tensile stress on CIS cores by lattice mismatch between core and shell layers.…”

Entanglement from density measurements: Analytical density functional for the entanglement of strongly correlated fermions

“…It has been shown that magnetic susceptibility can be an entanglement witness [27][28][29], which is used to point out the presence of entanglement. Also momentum-momentum correlation [30,31], energies [21,22], and probability density at highly symmetric points [22] have been proposed as entanglement indicators, which reproduce the general trend of entanglement. However, a quantity able to predict entanglement quantitatively and, in addition, with the potential of being experimentally measurable is still missing.…”

Quantum entanglement for two electrons in the excited states of helium-like systems

“…Understanding of entangled systems is important in other research areas such as quantum information [1], quantum computation [2] and quantum cryptography [3]. The investigations of quantum entanglement include the works on some model atoms like the Moshinsky atom [4][5][6][7][8], the Crandall atom [9] and the Hooke atom [9][10][11][12], and the works on artificial atoms like quantum dots [13][14][15][16][17]. Coe and D'Amico calculated the linear entropy for the ground state of the natural helium atom with wave functions constructed by using the products of hydrogenic wave functions, as well as using the density functional theory [10].…”