Biexcitons in coupled quantum dots as a source of entangled photons

Gywat, Oliver; Burkard, Guido; Loss, Daniel

doi:10.1103/physrevb.65.205329

Cited by 80 publications

(64 citation statements)

References 31 publications

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“…In particular, the Coulomb blockade exhibited by quantum dots is being used in experiments involving single charge and spin transport and manipulation [2 -4] as well as for optical experiments such as generation of single-photons [5][6][7][8]. Application of these systems for quantum communication and computation protocols is a vibrant area of research [9][10][11][12][13][14][15][16].…”

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confidence: 99%

Spin-Photon Entangling Diode

2007

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We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control of the diode bias and local gating allow for the generation of single photons that are entangled with a robust quantum memory based on the electron spins. Practical performance of this approach to controlled spin-photon entanglement is analyzed.Comment: 4 pages, 2 figures; figures update

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confidence: 99%

Spin-Photon Entangling Diode

2007

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“…The expected extended carrier spin lifetimes have been confirmed experimentally [5][6][7][8], and efficient room-temperature spin detection has also recently been demonstrated [9], which is encouraging for proposals of QDs in applications of quantum computing [10] and spintronic devices such as spin light-emitting devices [11]. Multiple QD structures have been proposed for creating entangled photon pairs, due to their separated biexciton state [12], which may simplify separate extraction of the two entangled photons. Entangled photon pairs are essential in quantum information technology for transmission and encryption.…”

Section: Introductionmentioning

confidence: 91%

Effects of a longitudinal magnetic field on spin injection and detection in InAs/GaAs quantum dot structures

Beyer¹,

Wang²,

Buyanova³

et al. 2012

J. Phys.: Condens. Matter

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Abstract. Effects of a longitudinal magnetic field on optical spin injection and detection in InAs/GaAs quantum dot (QD) structures are investigated by optical orientation spectroscopy. An increase in optical and spin polarization of the QDs is observed with increasing magnetic field in the range of 0-2 T, and is attributed to suppression of exciton spin depolarization within the QDs that is promoted by hyperfine interaction and anisotropic electron-hole exchange interaction. This leads to a corresponding enhancement in spin detection efficiency of the QDs by a factor of up to 2.5. At higher magnetic fields when these spin depolarization processes are quenched, electron spin polarization in anisotropic QD structures (such as double QDs that are preferably aligned along a specific crystallographic axis) still exhibits rather strong field dependence under non-resonant excitation. In contrast, such field dependence is practically absent in more "isotropic" QD structures (e.g. single QDs). We attribute the observed effect to stronger electron spin relaxation in the spin injectors (i.e. wetting layer and GaAs barriers) of the lower-symmetry QD structures, which also explains the lower spin injection efficiency observed in these structures.PACS numbers: 73.21. La, 78.67.Hc, 72.25.Fe, 72.25.Rb IntroductionSemiconductor quantum dot (QD) structures are currently under intense investigations in view of their potential applications in spin-based quantum information technology and nanospintronics, as the three-dimensional carrier confinement in these structures promises suppression of many spin relaxation mechanisms that are predominant in semiconductors of higher dimensionality [1]. In threeand two-dimensional structures, the most important spin relaxation mechanisms such as the D'yakonov-Perel and Elliott-Yafet mechanisms are promoted by the motion of carriers. For confined carriers in QDs, the lack of carrier motion efficiently deactivates these spin relaxation mechanisms. Furthermore, their atomic-like, discrete energy level structure restricts efficiency of phonon-induced inelastic scattering processes. Hyperfine interactions of confined carriers with nuclear spins of host lattice atoms within QDs [2,3] and carrier-carrier exchange interaction [4] become the dominant spin relaxation mechanisms at low temperatures. The expected extended carrier spin lifetimes have been confirmed experimentally [5][6][7][8], and efficient room-temperature spin detection has also recently been demonstrated [9], which is encouraging for proposals of QDs in applications of quantum computing

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“…Because of the similarity of this states with bonding or antibonding states these structures are also named QD molecules. This coupling, which can be controlled to a large degree by an external electric field, has been the subject of a large amount of work over the past years investigating both excitonic [103,104,105] and biexcitonic transitions [106,107]. In particular close to a resonance between spatially direct and indirect exciton states phonon-induced transitions can be strongly enhanced [108,73,109,110], which can also be interpreted as phonon-assisted tunneling [111,112].…”

Section: Quantum Dot Modelmentioning

confidence: 99%

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

Reiter

Kuhn

Glässl

et al. 2014

J. Phys.: Condens. Matter

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Abstract. For many applications of semiconductor quantum dots in quantum technology a well controlled state preparation of the quantum dot states is mandatory. Since quantum dots are embedded in the semiconductor matrix, the interaction with phonons plays often a major role in the preparation process. In this review, we discuss the influence of phonons on three basically different optical excitation schemes which can be used for the preparation of exciton, biexciton, and superposition states: a resonant excitation leading to Rabi rotations in the excitonic system, an excitation with chirped pulses exploiting the effect of adiabatic rapid passage, and an off-resonant excitation giving rise to a phononassisted state preparation. We give an overview over experimental and theoretical results showing the role of the phonons and compare the performance of the schemes for state preparation.

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Biexcitons in coupled quantum dots as a source of entangled photons

Cited by 80 publications

References 31 publications

Spin-Photon Entangling Diode

Spin-Photon Entangling Diode

Effects of a longitudinal magnetic field on spin injection and detection in InAs/GaAs quantum dot structures

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

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