Extending the time of coherent optical response in ensemble of singly-charged InGaAs quantum dots

Abstract

The ability to extend the time scale of the coherent optical response from large ensembles of quantum emitters is highly appealing for applications in quantum information devices. In semiconductor nanostructures, spin degrees of freedom can be used as auxiliary, powerful tools to modify the coherent optical dynamics. Here, we apply this approach to negatively charged (In,Ga)As/GaAs self-assembled quantum dots which are considered as excellent quantum emitters with robust optical coherence and high bandwidth. We study three-pulse spin-dependent photon echoes subject to moderate transverse magnetic fields up to 1 T. We demonstrate that the timescale of coherent optical response can be extended by at least an order of magnitude by the field. Without magnetic field, the photon echo decays with T2 = 0.45 ns which is determined by the radiative lifetime of trions T1 = 0.26 ns. In the presence of the transverse magnetic field, the decay of the photon echo signal is given by spin dephasing time of the ensemble of resident electrons T2,e ∼ 4 ns. We demonstrate that the non-zero transverse g-factor of the heavy holes in the trion state plays a crucial role in the temporal evolution and magnetic field dependence of the long-lived photon echo signal.

Temporal Sorting of Optical Multiwave-Mixing Processes in Semiconductor Quantum Dots

“…Further, we demonstrate the splitting of the photon echo into two cross-polarized pulses, which has potential applications for the transformation of the spin qubit of the photon into the time bin qubit in integrated semiconductor devices . These results have also important implications for the application of QD ensembles in quantum memory devices with high bandwidth . We stress that our results are not necessarily limited to the optical control of the phase evolution in ensembles of strongly localized excitons or trions as they can be directly adopted to control the phase evolution and the corresponding optical response of a single quantum emitter.…”

“…5 These results have also important implications for the application of QD ensembles in quantum memory devices with high bandwidth. 37 We stress that our results are not necessarily limited to the optical control of the phase evolution in ensembles of strongly localized excitons or trions as they can be directly adopted to control the phase evolution and the corresponding optical response of a single quantum emitter. Our demonstrations push forward the realization of arbitrary pulse sequences, as widely used in nuclear magnetic resonance, for quantum memory protocols or information processing in ensembles of QDs by optical methods.…”

A unipolar quantum dot diode structure for advanced quantum light sources

“…On the other hand, MBE with its high-vacuum and high purity growth conditions, enables the slow and controlled deposition of semiconductor nanostructures with a defect-free environment, resulting in high-coherence photon emission [6,18,[21][22][23]. In the following, the optical and quantum optical properties of the emitted photons from the n + −i−n ++ diode structure will be reported.…”

A Unipolar Quantum Dot Diode Structure for Advanced Quantum Light Sources

“…On the one hand, MOVPE allows for fast deposition of high-quality multilayers forming high-reflectivity DBRs, the growth being performed at high temperature and low vacuum. On the other hand, MBE, with its high-vacuum and high-purity growth conditions, enables the slow and controlled deposition of semiconductor nanostructures with a defect-free environment, resulting in high-coherence photon emission. ,,− In the following, the optical and quantum optical properties of the emitted photons from the n + –i–n ++ diode structure will be reported. Specifically, high single-photon purity and indistinguishability have been observed respectively via Hanbury–Brown and Twiss and Hong–Ou–Mandel-type (HOM) experiments.…”