Optical Control in Coupled Two-Electron Quantum Dots

Abstract

The dynamics of two electrons in a 2-dimensional quantum dot molecule in the presence of a time-dependent electromagnetic field is calculated from first principles. We show that carefully selected microwave pulses can exclusively populate a single state of the first excitation band and that the transition time can be further decreased by optimal pulse control. Finally we demonstrate that an oscillating charge localized state may be created by multiple transitions using a sequence of pulses.

Optimal control of a charge qubit in a double quantum dot with a Coulomb impurity

“…Monotonically convergent iterative schemes proposed by Tannor et al [31] and Rabitz et al [32] have been successfully applied to the control of different quantum phenomena, mainly related to chemical process [33,34]. In the last years, optimal control theory became a research area that has received increasing interest from the scientists studying emerging fields within quantum information science [35,36]. Modern quantum devices are systems where the wave function must be manipulated with highest possible precision using, for example, quantum gates.…”

“…In addition, quantum computation theoretically requires extremely high fidelity in the elementary quantum state transformations. Optical control of quantum dot based devices is of fundamental interest for a wide range of applications in quantum information [35,36,37,38,39,40]. For example, optical manipulation is an alternative in order to store qubits in the electron spin [35].…”

“…Hansen et. al [36] show that carefully selected microwave pulses can be used to populate a single state of the first excitation band in a two-electron DQD and that the transition time can be decreased using optimal pulse control. Heller et.…”

Optical control of entangled states in semiconductor quantum wells

“…12 Here we focus on a similar quasi-onedimensional setup and show that optical fields can lead to almost 100% fidelities of targeted entangled two-electron states in tens of picoseconds, thus improving both the operation time and the fidelity from earlier works by 1-2 orders of magnitude. In this context, we extend the previous single-particle 14,15 and two-particle 16,17 optimization studies into an all-round scheme to coherently control an arbitrary transition in a two-electron DQD. Moreover, we show that the control procedure validates for the maximization of the entanglement itself, which might have further implications for quantum information in solidstate devices.…”

“…Beyond few-level models, realistic DQDs have been controlled with gate voltages 10,11,13 and optimized laser pulses. [14][15][16][17] Murgida and co-workers 10,11 presented an scheme to reach desired excited states in two-electron DQDs by "navigating" in the energy spectrum with electric fields -an approach widely used for two-and threelevel systems. 12 Here we focus on a similar quasi-onedimensional setup and show that optical fields can lead to almost 100% fidelities of targeted entangled two-electron states in tens of picoseconds, thus improving both the operation time and the fidelity from earlier works by 1-2 orders of magnitude.…”