Logic and functional operations using a near-field optically coupled quantum-dot system

Sangu, Suguru; Kobayashi, Kiyoshi; Shojiguchi, Akira; Ohtsu, Motoichi

doi:10.1103/physrevb.69.115334

Cited by 84 publications

(58 citation statements)

References 28 publications

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“…With unique advantages, such as high nonlinear optical susceptibility, large electric-dipole moments of intersubband transitions, and great flexibility in designing devices [36][37][38], SQD system has wide applications in the fields of quantum optics and quantum information [39][40][41][42][43][44][45][46][47][48]. For example, the electromagnetically induced transparency (EIT) and the propagation of slow light have been realized in the SQD medium [43].…”

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confidence: 99%

Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules

Lü

Zheng

et al. 2011

Phys. Rev. A

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We propose two schemes for generating entanglement and quantum state transfer (QST) between two spatially separated semiconductor quantum dot molecules (QDMs) based on the voltagecontrolled tunneling effects. In the present schemes, two QDMs are trapped into two spatially separated cavities connected by a fiber, respectively. By numerically simulating the evolution of system, we show that the generation of entanglement and QST can be controlled by an external gate voltage in our schemes. Moreover, proposed schemes are robust against noise of system parameters.

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confidence: 99%

Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules

Lü

Zheng

et al. 2011

Phys. Rev. A

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“…2͑d͒. This indicates that the time scale of the near-field coupling is shorter than the decoherence time, and that coherent coupled states, such as symmetric and antisymmetric states, 14 determine the system dynamics. Furthermore, nutation never appears unless unbalanced initial exciton populations are prepared for ប⍀ 1D and ប⍀ 2D .…”

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confidence: 99%

Nanophotonic switch using ZnO nanorod double-quantum-well structures

Yatsui¹,

Sangu²,

Kawazoe³

et al. 2007

Applied Physics Letters

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The authors report on time-resolved near-field spectroscopy of ZnO / ZnMgO nanorod double-quantum-well structures ͑DQWs͒ for a nanometer-scale photonic device. They observed nutation of the population between the resonantly coupled exciton states of DQWs. Furthermore, they demonstrated switching dynamics by controlling the exciton excitation in the dipole-inactive state via an optical near field. The results of time-resolved near-field spectroscopy of isolated DQWs described here are a promising step toward designing a nanometer-scale photonic switch and related devices. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2743949͔ Systems of optically coupled quantum dots ͑QDs͒ should be applicable to quantum information processing. 1,2 Additional functional devices ͑i.e., nanophotonic devices 3-6 ͒ can be realized by controlling the exciton excitation in QDs. ZnO is a promising material for room-temperature operation, owing to its large exciton binding energy 7-9 and recent achievements in the fabrication of nanorod heterostructures. 10,11 This study used time-resolved near-field spectroscopy to demonstrate the switching dynamics that result from controlling the optical near-field energy transfer in ZnO nanorod double-quantum-well structures ͑DQWs͒. We observed nutation of the population between the resonantly coupled exciton states of DQWs, where the coupling strength of the near-field interaction decreased exponentially as the separation increased.To evaluate the energy transfer, three samples were prepared ͓Fig. 1͑a͔͒: ͑1͒ single-quantum-well structures ͑SQWs͒ with a well-layer thickness of L w = 2.0 nm ͑SQWs͒, ͑2͒ DQWs with L w = 3.5 nm with 6 nm separation ͑1-DQWs͒, and ͑3͒ three pairs of DQWs with L w = 2.0 nm with different separations ͑3, 6, and 10 nm͒, where each DQW was separated by 30 nm ͑3-DQWs͒. These thicknesses were determined by the transmission electron microscopy ͑TEM͒ measurement. ZnO / ZnMgO quantum-well structures ͑QWs͒ were fabricated on the ends of ZnO nanorods with a mean diameter of 80 nm using catalyst-free metal organic vapor phase epitaxy. 10 The average concentration of Mg in the ZnMgO layers used in this study was determined to be 20 at. %.The far-field photoluminescence ͑PL͒ spectra were obtained using a He-Cd laser ͑ = 325 nm͒ before detection using near-field spectroscopy. The near-field photoluminescence ͑NFPL͒ spectra were obtained using a He-Cd laser ͑ = 325 nm͒, collected with a fiber probe with an aperture diameter of 30 nm, and detected using a cooled chargecoupled device through a monochromator. Blueshifted PL peaks were observed at 3.499͑I S ͒, 3.429͑I 1D ͒, and 3.467 ͑I 3D ͒ eV in the far-and near-field PL spectra ͓Fig. 2͑a͔͒. We believe that these peaks originated from the respective ZnO QWs because their energies are comparable to the predicted ZnO well-layer thicknesses of 1.7͑I S ͒, 3.4͑I 1D ͒, and 2.2 ͑I 3D ͒ nm, respectively, calculated using the finite square-well potential of the quantum confinement effect in ZnO SQWs. 10 To confirm the near-field energy trans...

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“…There is growing interest in a variety of schemes that are based on the transfer of excitation between adjacent quantum dots, [55][56][57][58][59][60][61][62][63][64] and are now being envisaged for performing quantum computation. Such proposals generally aim to exploit the discrete, size-tunable, and intense character of quantum dot exciton transitions, as well as the fact that these processes can be switched very rapidly using optical excitation.…”

Section: Quantum Dotsmentioning

confidence: 99%

Resonance Energy Transfer: Theoretical Foundations and Developing Applications

Andrews¹

Tutorials in Complex Photonic Media

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Logic and functional operations using a near-field optically coupled quantum-dot system

Cited by 84 publications

References 28 publications

Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules

Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules

Nanophotonic switch using ZnO nanorod double-quantum-well structures

Resonance Energy Transfer: Theoretical Foundations and Developing Applications

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