Effect of confinement potential shape on exchange interaction in coupled quantum dots

Abstract

Exchange interaction has been studied for electrons in coupled quantum dots (QD's) by a configuration interaction method using confinement potentials with different profiles. The confinement potential has been parametrized by a two-centre power-exponential function, which allows us to investigate various types of QD's described by either soft or hard potentials of different range. For the soft (Gaussian) confinement potential the exchange energy decreases with increasing interdot distance due to the decreasing interdot tunnelling. For the hard (rectangular-like) confinement potential we have found a non-monotonic behaviour of the exchange interaction as a function of distance between the confinement potential centres. In this case, the exchange interaction energy exhibits a pronounced maximum for the confinement potential profile which corresponds to the nanostructure composed of the small inner QD with a deep potential well embedded in the large outer QD with a shallow potential well. This effect results from the strong localization of electrons in the inner QD, which leads to the large singlet-triplet splitting. Implications of this finding for quantum logic operations have been discussed.

16 pages, including 11 figures

References in corpus (6)

• Failure of standard approximations of the exchange coupling in nanostructures
• Exchange interaction and stability diagram of coupled quantum dots in magnetic fields
• Role of interactions in the far-infrared spectrum of a lateral quantum dot molecule
• Controlled exchange interaction for quantum logic operations with spin qubits in coupled quantum dots
• Magnetic Field Control of Exchange and Noise Immunity in Double Quantum Dots
• Experimental Observation of Electronic Coupling in GaAs Lateral Quantum Dot Molecules

Cited by in corpus (6)

• Effect of confinement potential geometry on entanglement in quantum dot-based nanostructures
• Gate control of a quantum dot single-electron spin in realistic confining potentials: anisotropy effects
• Tuning the exchange interaction by electric field in laterally coupled quantum dots
• Effect of a laser field in the confinement potential of two electrons in a double quantum dot
• Geometry induced entanglement transitions in nanostructures
• Periodicity of resonant tunneling current induced by the Stark resonances in semiconductor nanowire