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Near transform-limited single photon sources are required for perfect photon indistinguishability in quantum networks. Having such sources in nanodiamonds is particularly important since it can enable engineering hybrid quantum photonic…
We present a temperature dependent photoluminescence study of silicon optical nanocavities formed by introducing point defects into two-dimensional photonic crystals. In addition to the prominent TO phonon assisted transition from…
The third-order non-linearity of silicon gives rise to a spontaneous four-wave mixing process in which correlated photon pairs are generated. Sources based on this effect can be used for quantum computation and cryptography, and can in…
We report an efficient energy-time entangled photon-pair source based on four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks to suitable optimization, the source shows a large spectral brightness of 400\,pairs of…
The electron spins of semiconductor defects can have complex interactions with their host, particularly in polar materials like SiC where electrical and mechanical variables are intertwined. By combining pulsed spin resonance with ab-initio…
We demonstrate polarisation-preserving frequency conversion of single-photon-level light at 854 nm, resonant with a trapped-ion transition and qubit, to the 1550-nm telecom C band. A total photon in / fiber-coupled photon out efficiency of…
Negatively charged silicon vacancy centers (SiV$^-$) in diamond exhibit excellent spin coherence and optical properties, making them promising candidates for quantum technologies. However, the strain-induced inhomogeneous distribution of…
Fractional Chern insulators arise in topologically nontrivial flat bands, characterized by an integer Chern number C that corresponds to the number of dissipationless edge states in the non-interacting regime. Higher Chern numbers can…
Near infrared emission in silicon carbide is relevant for quantum technology specifically single photon emission and spin qubits for integrated quantum photonics, quantum communication and quantum sensing. In this paper we study the…
Spins bound to point defects are increasingly viewed as an important resource for solid-state implementations of quantum information technologies. In particular, there is a growing interest in the identification of new classes of defect…
We report on molecular beam epitaxy growth of symmetric InAs/InP quantum dots (QDs) emitting at telecom C-band (1.55 $\mu$m) with ultra-small excitonic fine-structure splitting of ~2 $\mu$eV. The QDs are grown on distributed Bragg reflector…
In this study, we address the selection rules with respect to the polarization of the optical excitation of two colour centres in 4H-SiC and 6H-SiC with potential for applications in quantum technology, the divacancy and the…
The unique quantum properties of the nitrogen-vacancy (NV) center in diamond have motivated efforts to find defects with similar properties in silicon carbide (SiC), which can extend the functionality of such systems not available to the…
The photoluminescence (PL) spectrum of Cu-containing silicon has a sharp zero-phonon (ZP) band at 1.014 eV. The luminescence center corresponding to this band is called Cu$_{PL}$ and is known to have the local $C_{3v}$ symmetry. A recent…
An optical absorption (OA) band of interstitial dichlorine monoxide molecules with peak at 4.7 eV and halfwidth 0.94 eV is identified in F2 laser - irradiated (photon energy=7.9 eV) synthetic silica glass bearing both interstitial O2 and…
The demand for single photon sources at $\lambda~=~1.54~\mu$m, which follows from the consistent development of quantum networks based on commercial optical fibers, makes Er:O$_x$ centers in Si still a viable resource thanks to the optical…
The coherence properties of optical emitters in crystals are crucial for quantum technologies and optical frequency metrology. Cooling to sub-kelvin temperatures can markedly enhance coherence, making it important to identify the parameters…
Color center is a promising platform for quantum technologies, but their application is hindered by the typically random defect distribution and complex mesoscopic environment. Employing cathodoluminescence, we demonstrate that an…
Optical and Hall-effect measurements have been performed on single crystals of Pb$_{0.77}$Sn$_{0.23}$Se, a IV-VI mixed chalcogenide. The temperature dependent (10--300 K) reflectance was measured over 40--7000 cm$^{-1}$ (5--870 meV) with an…
Motivated by the success of group IV colour centres in nanodiamonds (NDs) for hybrid technology requiring a single photon source, we study single germanium-vacancy (GeV$^-$) centres in NDs at room temperature with size rangingfrom 10 to 50…