Taming the telecom emission of spin-defects integrated in Si (QuantERA III)

1) Wider research context / theoretical framework
Optically-active spin defects in solids are color centers that combine the long coherence times of spins with the networking properties of photons. These properties make them excellent qubits, placing them at the core of quantum technologies such as entanglement-based quantum communications, high-connectivity quantum computing, and many-body quantum simulation. Recently, single color centers were isolated in silicon, promising a leap in scalability due to their telecom emission and direct compatibility with the most mature microelectronic and integrated photonic platforms.
2) Hypotheses / research questions / objectives
However, a major drawback is their limited optical coherence. This property, quantified by homogeneous and inhomogeneous broadening, drastically reduces photon indistinguishability, leading to poor entanglement fidelity and rates, thus hampering any application requiring multiqubit interactions. Optical decoherence mechanisms are further strongly intensified when color centers are integrated in silicon photonic nanostructures. TEMISIS squarely advances the "Quantum Phenomena and Resources (QPR)" agenda by introducing a rigorous interdisciplinary strategy to address the major challenge preventing the application of color center based quantum technologies: optically coherent and scalable color center qubits. By exploring the fundamental physics behind the optical coherence of silicon color centers and addressing its limitations, we enable high-quality and telecom-ready photon mediated entanglement directly integrated into the technologically most mature electronic and photonic platform.
3) Approach/methods
TEMISIS directly targets the bottleneck of decoherence by uniting two advances: 1) exquisite control of color center formation, positioning, distance to surfaces, and material impurities via epitaxial growth with molecular beams; with 2) strain tuning via on-chip waveguide-integrated MEMS actuators. This novel, interdisciplinary approach will allow us to mitigate homogeneous and inhomogeneous broadening in two of the most promising color centers in silicon: the G and T centers.
TEMISIS tackles the challenging demonstration of true indistinguishable single photon emission from single integrated color centers and between two independent color centers in separate cavities with active spectral alignment.
4) Level of originality / innovation
TEMISIS will open the path to high-fidelity entanglement-based networks and large-scale silicon integrated quantum photonics.
5) Primary researchers involved
Project coordinator:
Anaïs Dréau, Centre National de la Recherche Scientifique (CNRS), France
PIs of (sub)projects:
Jean-Michel Gérard, The French Alternative Energies and Atomic Energy Commission (CEA) France
Moritz Brehm, Johannes Kepler University Linz, Austria
Carlos Errando-Herranz, Delft University of Technology, Netherlands
Ádám Gali, Wigner Research Centre for Physics (WRCP), Hungary