No abstract

-Single photon emitters (SPEs) are at the basis of many applications for quantum information management. Semiconductor-based SPEs are best suited for practical implementations because of high design flexibility, scalability and integration potential in practical devices. Single photon emission from ordered arrays of InGaN nano-disks embedded in GaN nanowires is reported. Intense and narrow optical emission lines from quantum dot-like recombination centers are observed in the blue-green spectral range. Characterization by electron microscopy, cathodoluminescence and micro-photoluminescence indicate that single photons are emitted from regions of high In concentration in the nano-disks due to alloy composition fluctuations. Single photon emission is determined by photon correlation measurements showing deep antibunching minima in the second order correlation function. The present results are a promising step towards the realization of on-site/on-demand single photon sources in the blue-green spectral range operating in the GHz frequency range at high temperatures.Introduction. -Single photons are ideal "flying" qubits to convey quantum information between distant nodes of a quantum network. Reliable and controlled generation of single photons is therefore a crucial step to develop applications for quantum communication, quantum information processing and quantum metrology [1,2]. Single photons can be emitted in principle by material entities possessing discrete energy levels, as they need a finite time to "recharge" after emission of one photon. The standard method to assess single photon emission is to measure the second order photon correlation function by Hanbury-Brown and Twiss (HBT) interferometry. As shown in Fig. 1, single photons are either reflected or transmitted by a beam splitter, so that the probability of simultaneous detection in the two detectors of the interferometer is zero. The detection events are stored in a Time-Correlated Single Photon Counter (TCSPC), and the resulting correlation function g 2 (τ) shows an

The optical emission of InGaN quantum dots embedded in GaN nanowires is dynamically controlled by a surface acoustic wave (SAW). The emission energy of both the exciton and biexciton lines is modulated over a 1.5 meV range at ~330 MHz. A small but systematic difference in the exciton and biexciton spectral modulation reveals a linear change of the biexciton binding energy with the SAW amplitude. The present results are relevant for the dynamic control of individual single photon emitters based on nitride semiconductors.Surface acoustic waves induce periodic strain and piezoelectric fields near a semiconductor surface which can dynamically modify their basic properties. The use of SAWs is an expanding research field, which has been widely applied to semiconductor quantum wells (QWs) 1-3 , wires 4-6 and dots (QDs) [7][8][9][10][11] .By controlling the excitonic emission in III-V semiconductor QDs by SAWs, high repetition rate single photon sources (SPSs) 7-9 and periodic laser mode feeding 12 have been reported. Also, dynamic control of individual QDs 11 and on-demand single-electron transfer between distant quantum dots 13 have been demonstrated. In a more general context, a proposal for onchip quantum transducers based on SAWs enabling long-range coupling of many qubits has been recently put forward 14 . In addition to the band-edge modulation, which determines the QD emission wavelength, the tunable strain field of the SAW can be used to modify other properties related to the band structure, as the exciton binding energy, in a similar way as static strain field 15 . While most of the SAW-related work reported in semiconductor structures refers to III-V systems, studies on group III-Nitrides are scarce. Extension of these techniques to group III-Nitride systems is important, as their large gap enables highpower/high-temperature applications and high repetition rate SPSs covering a broad spectral range. Also, the high sound velocities and the stronger electromechanical coupling coefficients of nitrides, as compared to (Al,Ga

The morphology and adhesion energy of nanosized metal particles supported on dielectrics is a puzzling issue since, due to the increasing contribution of surfaces and interfaces in their energetics, their equilibrium shape escapes the rules established for large objects.