arXiv subjects

Petros-Panagis Filippatos

Publications and source records attributed to Petros-Panagis Filippatos.

3 recordsLinked to original sources

arXiv2026

Single-photon emitters and spin-photon interfaces in silicon

Single photons enable the distribution of quantum information over large distances and thus play a major role in quantum technologies such as communication and computing. Solid-state emitters are practical and efficient sources of single photons that can be manufactured in large numbers. When combined with a spin, the resulting spin-photon interfaces can store quantum states for extended periods and serve as the basis for quantum networks and repeaters. Among the many host materials explored over the past few decades, silicon stands out for its advanced nanofabrication, the maturity of its integrated photonics and microelectronics, and its high isotopic purity, which leads to exceptionally long spin coherence. These properties position silicon single-photon emitters and spin-photon interfaces among the most promising hardware platforms for implementing quantum networks and distributed quantum information processors. This review summarizes the current state of the art and open challenges towards coherent single-photon sources and scalable spin-photon interfaces based on color centers and erbium dopants in nanophotonic silicon structures.

quant-ph↗

arXiv2025

Multiplet structure of chromium(III) dopants in wide band gap materials

Transition metal doping is commonly used for altering the properties of solid-state materials to suit applications in science and technology. Partially filled $d$-shells of transition metal atoms lead to electronic states with diverse spatial and spin symmetries. Chromium(III) cations have shown great potential for designing laser materials and, more recently, for developing spin qubits in quantum applications. They also represent an intriguing class of chemical systems with strongly correlated multi-reference excited states, due to the $d^3$ electron configuration. These states are difficult to describe accurately using single-reference quantum chemical methods such as density functional theory (DFT), the most commonly used method to study the electronic structures of solid-state systems. Recently, the periodic effective Hamiltonian of crystal field (pEHCF) method has been shown to overcome some limitations arising in the calculations of excited $d$-states. In this work, we assess the suitability of DFT and pEHCF to calculate the electronic structure and $d$-$d$ excitations of chromium(III) dopants in wide band gap host materials. The results will aid computational development of novel transition metal-doped materials and provide a deeper understanding of the complex nature of transition metal dopants in solids.

cond-mat.mtrl-sci↗

arXiv2025

Revisiting intrinsic spin defects in hexagonal boron nitride with r2SCAN

Hexagonal boron nitride (hBN) is a wide band gap, van der Waals material that is highly promising for solid-state quantum technologies as a host of optically addressable, paramagnetic spin defects. Intrinsic and extrinsic point defects provide a range of emission energies, but the atomic-level structures related to observed transitions are not fully characterised. In this work, intrinsic point defects in bulk hBN are modelled using density functional theory at the level of the meta-generalized gradient approximation (meta-GGA), considering their formation energies, electronic spectra and magnetic properties. The meta-GGA exchange-correlation functional r2SCAN is found to offer a balance between accuracy and computational efficiency for specific properties, while its predictive performance for bound-exciton stability is limited when compared to higher-level hybrid functionals. This implies opportunities for its use in optimised, hierarchical computational defect screening workflows. Under revised criteria, VB-, BN0, Bi+ and Ni+ defects are identified as stable colour centres with zero-phonon emission within technologically desirable wavelengths, making them promising for use in quantum networks and sensors.

quant-ph↗