Optical control of the spin of a magnetic atom in a semiconductor quantum dot

Abstract

Abstract:The control of single spins in solids is a key but challenging step for any spin-based solid-state quantumcomputing device. Thanks to their expected long coherence time, localized spins on magnetic atoms in a semiconductor host could be an interesting media to store quantum information in the solid state. Optical probing and control of the spin of individual or pairs of Manganese (Mn) atoms (S = 5/2) have been obtained in II-VI and III-V semiconductor quantum dots during the last years. In this paper, we review recently developed optical control experiments of the spin of an individual Mn atoms in II-VI semiconductor self-assembled or strain-free quantum dots (QDs). We first show that the fine structure of the Mn atom and especially a strained induced magnetic anisotropy is the main parameter controlling the spin memory of the magnetic atom at zero magnetic field. We then demonstrate that the energy of any spin state of a Mn atom or pairs of Mn atom can be independently tuned by using the optical Stark effect induced by a resonant laser field. The strong coupling with the resonant laser field modifies the Mn fine structure and consequently its dynamics. We then describe the spin dynamics of a Mn atom under this strong resonant optical excitation. In addition to standard optical pumping expected for a resonant excitation, we show that the Mn spin population can be trapped in the state which is resonantly excited. This effect is modeled considering the coherent spin dynamics of the coupled electronic and nuclear spin of the Mn atom optically dressed by a resonant laser field. Finally, we discuss the spin dynamics of a Mn atom in strain-free QDs and show that these structures should permit a fast optical coherent control of an individual Mn spin.

Single Magnetic Impurities in Colloidal Quantum Dots and Magic-Size Clusters

“…Additionally, optical spin orientation of a single magnetic ion in a QD has been demonstrated, , as has optical spin detection . Coherent spin precession of an individual Mn 2+ ion has been demonstrated using pump–probe techniques, and optical pumping and readout of a specific spin state has also been achieved. ,, Although manganese is by far the most thoroughly investigated dopant for SDQD studies, − ,,, individual cobalt, chromium, and iron impurities have also been examined in individual self-assembled QDs, with exciting results from each.…”

Large and Uniform Optical Emission Shifts in Quantum Dots Strained along Their Growth Axis

“…Therefore, this strategy could be applied to characterize the strain response of QDs or optically active defects in other important material systems. In particular, determining the strain response of individual spins of charge carriers 31 or single dopants 32 in QDs is highly relevant for the future developments of spin-based hybrid optomechanics. 33 Along the same line, the strain response of dye molecules, which can also serve as local mechanical sensors, 34 could be reliably determined using this technique.…”

Optically controlled spin-polarization memory effect on Mn delta-doped heterostructures

“…Much attention has been devoted to the optical orientation of the Mn acceptors and their spin manipulation in semiconductors 6 7 . This effect has been investigated mainly in GaAs: Mn bulk samples by resonant excitation of electrons from residual donors in the vicinity of a Mn acceptor or in quantum dots, where the coupling between the carriers and the Mn ion is reinforced by their strong overlap 8 9 .…”