Spins in Optically Active Quantum Dots

Gywat, Oliver; Krenner, Hubert J.; Berezovsky, Jesse

doi:10.1002/9783527628988

Cited by 34 publications

(45 citation statements)

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“…As opposed to self-assembled QDs, gate-defined systems cannot confine electrons and holes at the same time and are therefore optically inactive [27]. Currently, experiments are almost exclusively carried out on gated 2DEGs, and new experimental challenges may be encountered when 2D hole gases are used instead [192].…”

Section: Dynamic Nuclear Polarization and Alternative Host Materialsmentioning

confidence: 99%

“…Such QDs are typically lens-shaped, with heights of ∼ 5 nm (growth direction) and diameters ∼ 20 nm, and confinement results from the difference in the conduction and valence band edges of the involved materials. Alternatively, interface fluctuation QDs arise from monolayer fluctuations in thin quantum wells, typically resulting in GaAs dots within AlGaAs [27]. The second category, lateral QDs, is based on two-dimensional electron and hole gases (2DEGs, 2DHGs), which exist in heterostructures from materials with suitable band properties and additional dopants.…”

Section: Promising Quantum Dot Structures Definition Of Lifetimementioning

confidence: 99%

“…Therefore, selfassembled QDs are typically operational at 4 K, the boiling temperature of 4 He. Moreover, they are optically active and feature strong interband transitions with "almost hard" selection rules [27,57,85]. Exploiting this property, self-assembled QDs are primarily studied using optical means, and heterostructures have been designed which allow precise control over the charge states [134,135].…”

Section: A Self-assembled Quantum Dotsmentioning

confidence: 99%

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Prospects for Spin-Based Quantum Computing in Quantum Dots

Kloeffel

Loss

2013

Annu. Rev. Condens. Matter Phys.

388

410

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Experimental and theoretical progress toward quantum computation with spins in quantum dots (QDs) is reviewed, with particular focus on QDs formed in GaAs heterostructures, on nanowire-based QDs, and on self-assembled QDs. We report on a remarkable evolution of the field where decoherence -one of the main challenges for realizing quantum computers -no longer seems to be the stumbling block it had originally been considered. General concepts, relevant quantities, and basic requirements for spin-based quantum computing are explained; opportunities and challenges of spin-orbit interaction and nuclear spins are reviewed. We discuss recent achievements, present current theoretical proposals, and make several suggestions for further experiments.

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Section: Dynamic Nuclear Polarization and Alternative Host Materialsmentioning

confidence: 99%

Section: Promising Quantum Dot Structures Definition Of Lifetimementioning

confidence: 99%

Section: A Self-assembled Quantum Dotsmentioning

confidence: 99%

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Prospects for Spin-Based Quantum Computing in Quantum Dots

Kloeffel

Loss

2013

Annu. Rev. Condens. Matter Phys.

388

410

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“…1,2 It is relatively isolated from the solid state effects and at the same time is accessible for coherent manipulation and can be interfaced optically. The coherence in this system is mainly limited by the hyperfine coupling with the nuclear spin bath.…”

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confidence: 99%

Vanishing electrongfactor and long-lived nuclear spin polarization in weakly strained nanohole-filled GaAs/AlGaAs quantum dots

et al. 2016

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GaAs/AlGaAs quantum dots grown by in situ droplet etching and nanohole infilling offer a combination of strong charge confinement, optical efficiency, and spatial symmetry required for polarization entanglement and spin-photon interface. Here we study spin properties of such dots. We find nearly vanishing electron g-factor (g e < 0.05), providing a route for electrically driven spin control schemes. Optical manipulation of the nuclear spin environment is demonstrated with nuclear spin polarization up to 60% achieved. NMR spectroscopy reveals the structure of two types of quantum dots and yields the small magnitude of residual strain ε b < 0.02% which nevertheless leads to long nuclear spin lifetimes exceeding 1000 s. The stability of the nuclear spin environment is advantageous for applications in quantum information processing.Central spin in semiconductor quantum dots is a prime candidate for applications in quantum information technologies. 1,2 It is relatively isolated from the solid state effects and at the same time is accessible for coherent manipulation and can be interfaced optically. The coherence in this system is mainly limited by the hyperfine coupling with the nuclear spin bath. 3,4 Single spin qubit manipulation in these structures, therefore, demands an auxiliary control over nuclear spin environment. Such control can be realized by maximizing polarization of 10 4 − 10 5 nuclei in a single quantum dot, 5-7 enabling the formation of well-defined nuclear spin states and in effect reducing the influence of the nuclear field fluctuations. 8,9 Central spin manipulation in semiconductor quantum dot (QD) system using resonant ultrafast optical pulses 10,11 has been demonstrated but scalability in such schemes is challenging. An alternative approach is to induce controlled spin rotation by manipulating the coupling to the external magnetic field. 12 This can be achieved by electrical modulation of the g-factor. However, such scheme critically depends on the ability to change the sign of g, thus requiring quantum dots with close to zero electron or hole g-factor. 13,14 Self-assembled InGaAs/GaAs QD has been the primary system of choice for spin studies over the last two decades, as quantum confinement in monolayer-fluctuation GaAs/AlGaAs dots is too weak. Only recently the potential of droplet epitaxial (DE) grown GaAs QDs has been identified. [15][16][17] In particular nanohole-filled droplet epitaxial (NFDE) dots formed by in situ etching and nanohole infilling 18 provide confinement and excellent optical efficiency, while on the other hand exhibiting high symmetry not achievable previously in self-assembled dots. 19 Such unique com-1 arXiv:1507.06553v1 [cond-mat.mes-hall]

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“…1,2 In this respect, the need to selectively rotate a specific spin qubit within a quantum register while simultaneously controlling interactions between spins is challenging. Such selective addressing requires that each qubit has a unique resonance frequency or calls for highly local ( 100 nm) time-dependent magnetic fields to selectively rotate a specific qubit.…”

mentioning

confidence: 99%