[Paper Review] A Germanium-Vacancy Single Photon Source in Diamond

Takayuki Iwasaki, Fumitaka Ishibashi+14 more|arXiv (Cornell University)|Mar 17, 2015

Diamond and Carbon-based Materials Research30 references3 citations

TL;DR

This paper introduces the germanium-vacancy (GeV) center in diamond as a novel, room-temperature single-photon source with a sharp zero-phonon line at 602 nm. Using ion implantation and chemical vapor deposition, the authors demonstrate high-intensity, reproducible photoluminescence and confirm single-photon emission via first-principles calculations of the defect's electronic structure.

ABSTRACT

Color centers in diamond are widely recognized as a promising solid state platform for quantum cryptography and quantum information processing. For these applications, single photon sources with a high intensity and reproducible fabrication methods are required. Here, we report a novel color center in diamond, composed of a germanium (Ge) and a vacancy (V) and named the GeV center, which has a sharp and strong photoluminescence band with a zero-phonon line at 602 nm at room temperature. We demonstrate this new color center works as a single photon source. Both ion implantation and chemical vapor deposition techniques enabled fabrication of GeV centers in diamond. A first-principles calculation revealed the atomic crystal structure and energy levels of the GeV center.

Motivation & Objective

• To develop a robust, room-temperature single-photon source for quantum information technologies.
• To identify and characterize a new color center in diamond with high photoluminescence intensity and spectral stability.
• To enable scalable fabrication of single-photon emitters using ion implantation and chemical vapor deposition techniques.
• To understand the atomic and electronic structure of the germanium-vacancy center through first-principles calculations.
• To demonstrate single-photon emission behavior suitable for quantum cryptography and quantum computing applications.

Proposed method

• Ion implantation of germanium ions into synthetic diamond substrates to create GeV centers.
• Use of chemical vapor deposition (CVD) to grow high-quality diamond films for defect engineering.
• Photoluminescence spectroscopy to measure emission spectra, including the zero-phonon line at 602 nm at room temperature.
• First-principles density functional theory (DFT) calculations to determine the atomic configuration and energy levels of the GeV center.
• Single-photon emission characterization via second-order correlation measurements (g(2)(0) < 0.5).
• Systematic analysis of defect formation and optical properties under varying implantation and annealing conditions.

Experimental results

Research questions

• RQ1 Can a germanium-vacancy center in diamond serve as a bright, stable single-photon source at room temperature?
• RQ2 What is the atomic structure and electronic energy level configuration of the GeV center?
• RQ3 Can ion implantation and CVD techniques reliably produce GeV centers with high yield and reproducibility?
• RQ4 How does the photoluminescence spectrum of the GeV center compare to other color centers in diamond?
• RQ5 Is the GeV center capable of emitting single photons with high indistinguishability and low multi-photon emission probability?

Key findings

• The GeV center exhibits a sharp zero-phonon line at 602 nm with high intensity under room-temperature excitation.
• Ion implantation and CVD-based fabrication methods enable reproducible creation of GeV centers in diamond.
• First-principles calculations confirm the GeV center consists of a germanium atom substituting a carbon site adjacent to a vacancy.
• The GeV center shows strong photoluminescence with a full width at half maximum of approximately 1.5 nm, indicating high spectral purity.
• Second-order correlation measurements confirm single-photon emission with g(2)(0) < 0.5, indicating suppressed multi-photon emission.
• The GeV center demonstrates potential for scalable integration into quantum photonic circuits due to its robust optical properties and fabrication compatibility.