Prepositioned single quantum dot in a lateral electric field

Reimer, Michael E.; Korkusiński, Marek; Dalacu, Dan; Jacques, Laurent; Lapointe, J.; Poole, Philip J.; Aers, G. C.; McKinnon, W. R.; Hawrylak, Paweł; Williams, Robin L.

doi:10.1103/physrevb.78.195301

Cited by 60 publications

(91 citation statements)

References 26 publications

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“…For a sufficiently large electric field the interaction terms exactly cancel the correlation corrections, resulting in a degeneracy of the biexciton and exciton emission. Results from Full Configuration Interaction calculations [73,74] are shown in Fig. 11a where the redshifting exciton and blueshifting biexciton result in removal of the biexciton binding energy at a field of 6.5 kV/cm.…”

Section: Non-classical Light Sourcesmentioning

confidence: 99%

“…In anisotropic quantum dots the electron-hole exchange interaction splits the two excitonic states by ¡ AES (see in the ¡ AES through the application of external magnetic [70] and electric [43,44] fields, or through spectral filtering [71], applied uniaxial stress [72], and quantum size and composition engineering [50][51][52][53]. An alternative scheme [73,74] involves manipulation of the biexciton binding energy. Consider a quantum dot for which the biexciton binding energy is zero.…”

Section: Non-classical Light Sourcesmentioning

confidence: 99%

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Directed self‐assembly of single quantum dots for telecommunication wavelength optical devices

Dalacu¹,

Reimer

Frédérick

et al. 2010

Laser & Photonics Reviews

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Strong confinement of charges in few electron systems such as in atoms, molecules and quantum dots leads to a spectrum of discrete energy levels that are often shared by several degenerate quantum states. Since the electronic structure is key to understanding their chemical properties, methods that probe these energy levels in situ are important. We show how electrostatic force detection using atomic force microscopy reveals the electronic structure of individual and coupled self-assembled quantum dots. An electron addition spectrum in the Coulomb blockade regime, resulting from a change in cantilever resonance frequency and dissipation during tunneling events, shows one by one electron charging of a dot. The spectra show clear level degeneracies in isolated quantum dots, supported by the first observation of predicted temperature-dependent shifts of Coulomb blockade peaks. Further, by scanning the surface we observe that several quantum dots may reside on what topologically appears to be just one. These images of grouped weakly and strongly coupled dots allow us to estimate their relative coupling strengths.

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Section: Non-classical Light Sourcesmentioning

confidence: 99%

Section: Non-classical Light Sourcesmentioning

confidence: 99%

Directed self‐assembly of single quantum dots for telecommunication wavelength optical devices

Dalacu¹,

Reimer

Frédérick

et al. 2010

Laser & Photonics Reviews

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“…The s-p orbital energy splitting is estimated by assuming a 2:1 electron versus hole orbital energy ratio, which is determined for InAs/InP quantum dots. 27 The total s-p orbital splitting of 17 meV was obtained from Figure 1c.…”

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confidence: 99%

Single Electron Charging in Optically Active Nanowire Quantum Dots

Kouwen¹,

Reimer²,

Hidma³

et al. 2010

Nano Lett.

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We report optical experiments of a charge tunable, single nanowire quantum dot subject to an electric field tuned by two independent voltages. First, we control tunneling events through an applied electric field along the nanowire growth direction. Second, we modify the chemical potential in the nanowire with a back-gate. We combine these two field-effects to isolate a single electron and independently tune the tunnel coupling of the quantum dot with the contacts. Such charge control is a first requirement for opto-electrical single electron spin experiments on a nanowire quantum dot.KEYWORDS Nanowires, optically-active quantum dots, single electron charging, opto-electronics S ingle, optically active quantum dots are widely investigated due to the ability to combine both single electron charging 1,2 and single 3 or entangled 4 photonemission, which are all key requirements for quantum information processing applications. 5 Nanowire quantum dots (NW-QDs) offer additional functionalities over selfassembled quantum dots since they are embedded in a onedimensional system instead of a three-dimensional host matrix. Therefore, the single electron (hole) transport channel is naturally aligned to the optically active quantum dot in the nanowire, advantageous for combining both quantum optics 6 and transport. [7][8][9] In addition, due to the small radial dimensions of the nanowires, electrostatic gate geometries are highly versatile 7,8 and axial heterostructure design is not limited by strain. As an example, the combination of Si sections, which are free of nuclear spins, with optically addressable electronic levels in III-V materials is promising for extending electron spin storage times. Prior to the work presented here, we have shown that a single InAsP quantum dot grown in an InP nanowire geometry is optically active, exhibits narrow emission lines, spin polarization memory effects, 10 and can be embedded in a LED device geometry. 11 Furthermore, it is predicted that NW-QDs are ideal sources of entangled photons due to the nanowire symmetry. 12 Recently, an electron spin-to-charge conversion read-out scheme has been proposed, 13 which is compatible with controlled storage of carriers up to microseconds. 14 Such storage times are promising since single spins in selfassembled quantum dots (SA-QDs) have been initialized, coherently manipulated, and read-out within picosecond time scales. 15,16 The proposed spin read-out scheme 13 highly depends on the overall tunnel coupling between the SA-QD energy levels and the continuum, determined by the quantum dot-to-contact spatial separation, which is fixed during growth. 17 In this letter, we present electrical control and optical read-out of the number of electrons residing in a single InAs 0.25 P 0.75 quantum dot embedded in an InP nanowire. We first identify the neutral exciton by photocurrent spectroscopy. Second, we demonstrate that the electron number can be controlled by an electric field applied along the nanowire growth direction or by an electrostatic bac...

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“…Specifically, a small anisotropic energy difference, can make the emitted x−polarized and y−polarized photon pairs distinguishable, and thus the entanglement between the photons is largely wiped out. There have been a few proposals to overcome this problem, e.g., by spectrally filtering indistinguishable photon pairs 13 , by applying external fields to make the exciton states degenerate 14 , and suppressing the biexciton binding energy in combination with time reordering 17,18 , but these techniques have their own set of problems and are far from optimal.…”

Section: Introductionmentioning

confidence: 99%

Generation of entangled photon pairs from a single quantum dot embedded in a planar photonic-crystal cavity

Pathak

Hughes

2009

Phys. Rev. B

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We present a formal theory of single quantum-dot coupling to a planar photonic crystal that supports quasi-degenerate cavity modes, and use this theory to describe, and optimize, entangledphoton-pair generation via the biexciton-exciton cascade. In the generated photon pairs, either both photons are spontaneously emitted from the dot, or one photon is emitted from the biexciton spontaneously and the other is emitted via the leaky-cavity mode. In the strong-coupling regime, the generated photon pairs can be maximally entangled, in qualitative agreement with the simple dressed-state predictions of Johne et al. [Phys. Rev. Lett. vol. 100, 240404 (2008)]. We derive useful and physically-intuitive analytical formulas for the spectrum of the emitted photon pairs in the presence of exciton and biexciton broadening, which is necessary to connect to experiments, and demonstrate the clear failure of using a dressed-state approach. We also present a method for calculating and optimizing the entanglement between the emitted photons, which can account for post-sample spectral filtering. Pronounced entanglement values of greater than 80% are demonstrated using experimentally achievable parameters, even without spectral filtering.

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Prepositioned single quantum dot in a lateral electric field

Cited by 60 publications

References 26 publications

Directed self‐assembly of single quantum dots for telecommunication wavelength optical devices

Directed self‐assembly of single quantum dots for telecommunication wavelength optical devices

Single Electron Charging in Optically Active Nanowire Quantum Dots

Generation of entangled photon pairs from a single quantum dot embedded in a planar photonic-crystal cavity

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