Lead-related quantum emitters in diamond

Abstract

We report on quantum emission from Pb-related color centers in diamond following ion implantation and high temperature vacuum annealing. First-principles calculations predict a negatively-charged Pb-vacancy center in a split-vacancy configuration, with a zero-phonon transition around 2.3 eV. Cryogenic photoluminescence measurements performed on emitters in nanofabricated pillars reveal several transitions, including a prominent doublet near 520 nm. The splitting of this doublet, 2 THz, exceeds that reported for other group-IV centers. These observations are consistent with the PbV center, which is expected to have the combination of narrow optical transitions and stable spin states, making it a promising system for quantum network nodes.

Ultrabright single-photon emission from germanium-vacancy zero-phonon lines: deterministic emitter-waveguide interfacing at plasmonic hot spots

“…Cryogenic characterization shows symmetry-protected optical transitions for the synthesized GeV centers in NDs (see Figure 1c), following the reported trend for bulk diamonds [16][17][18][19] (see Figure 1b). Furthermore, ZPLs indicate a large splitting in the ground state (up to 870 GHz), which is ~17 times larger than siliconvacancy (SiV) 19 , and ~6 times larger than GeV in bulk 16,35,36 , becoming close to tin-vacancy (SnV) with 850 GHz 17 .…”

“…However, a lack of symmetry in nitrogen-vacancy molecule structure limits severely the coherent part of the emission, with the emission to a zero-phonon line (ZPL) being only 4%, and makes the frequency of optical transitions being very sensitive to the environment. Replacing nitrogen with larger atoms of group IV in the periodic table (e.g., with a silicon atom that is a ~1.5 times larger in size than a carbon atom) enabled to circumvent the issues associated with symmetry arguments [15][16][17][18][19][20] (see Figure 1a,b). This opened a way toward demonstrations of indistinguishable solid-state quantum emitters (without the need for electric field tuning) with spectral stability and large ZPLs 21 .…”

Building Blocks for Quantum Network Based on Group‐IV Split‐Vacancy Centers in Diamond

“…The strong spin–orbit (SO) coupling and dynamical Jahn–Teller (DJT) interaction lift the orbital degeneracy of these states, leading to a pair of split ground and excited states, each with double spin degeneracy, as shown in Figure b. At cryogenic temperature and zero magnetic field, the transition between these energy levels lead to a characteristic four‐line emission pattern in ZPL spectrum of SiV − , GeV − , SnV − , and PbV − centers, as shown in Figure c. These optically allowed transitions form a double‐Λ system, which has been utilized to realize orbital‐based coherent control schemes .…”

“…By placing GeV − centers in a less noisy environment, phonon‐mediated orbital transitions takes the dominant role again to limit the spin coherence time, as evidenced by the temperature dependence of transition linewidth and of the decay rate of optical Rabi oscillations . Given the significantly larger orbital splitting in SnV − and PbV − centers (see Table ), these emerging quantum emitters stand a good chance to outperform SiV − and GeV − centers on spin coherence time, which is not experimentally confirmed yet.…”

Diamond as a Platform for Integrated Quantum Photonics

“…Other defects which received recent attention are the tin vacancy (SnV) color center (emission wavelength ≃620 nm), the neutral SiV 0 center (emission wavelength ≃950 nm), and Pb‐related color centers (emission wavelength ≃520–560 nm) . Particular interest in these defects stems from the fact that they are expected to possess all the favorable optical properties of negative SiV and GeV centers because of the equivalent inversion symmetry of their electronic structures but much longer spin coherence times (with an electronic spin coherence time ≃1 ms already measured for the SiV° center), making them attractive candidates for the realization of long‐distance quantum networks.…”