Magnetic Qubit in a Non-Magnetic Semiconductor Quantum Dot Molecule

Abstract

We consider a system of two vertical lens-shaped circular InAs/GaAs quantum dots when an external magnetic field is applied along the system's growth direction. The quantum dots have substantially different diameters in contrast to most of the known systems. We discuss a possibility to coherently drive coupled electronic ground states (to relocate electronic wave functions from one dot to another). This can be described as a manipulation of a magnetic iso-spin qubit. At the same time the relocation correlates with the anti-crossing behavior of the two lowest electronic states of the quantum dot molecule and generates unusual features of the magnetic susceptibility of the system. It follows from this theoretical study that in our non-magnetic system we can perform and monitor the magnetic qubit. The qubit can be dynamically driven by an external magnetic field and retraced from the magnetic susceptibility changes. A few single-qubit quantum gates can be performed.