Low-Temperature Spectroscopic Investigation of Lead-Vacancy Centers in Diamond Fabricated by High-Pressure and High-Temperature Treatment

TL;DR

This study investigates the optical properties of lead-vacancy centers in diamond created by ion implantation and high-temperature annealing, revealing their potential for long spin coherence times at low temperatures.

Contribution

It provides the first detailed spectroscopic analysis of PbV centers in diamond, demonstrating their optical characteristics and symmetry, and highlighting their suitability for quantum applications.

Findings

Observed intense emission peaks at 550 and 554 nm.

Identified large ground state splitting of approximately 3900 GHz.

Indicated potential for long spin coherence times at low temperatures.

Abstract

We report the optical observation of lead-vacancy (PbV) centers in diamond fabricated by Pb ion implantation and subsequent high-temperature annealing (2100 {\deg}C) under high pressure (7.7 GPa). Their optical properties were characterized by photoluminescence at varying temperatures down to 5.7 K. We observed intense emission peaks at 550 and 554 nm with a large splitting of approximately 3900 GHz. The two lines are thought to correspond to the zero phonon line (ZPL) of PbV centers with split ground and excited states. A cubic trend of the ZPL width was observed while varying temperature. We performed polarization measurements of the two lines in a single PbV center, showing nearly orthogonal dipole polarizations. These optical measurements strongly indicate that the PbV center possesses D3d symmetry in the diamond lattice. The observed large ground state splitting significantly suppresses the phonon-mediated transition, which causes decoherence of the electron spin state of the group IV color centers in diamond, expecting a long spin coherence time at a temperature of approximately 8 K.