Engineering spin qubits with silicon carbide and oxides through materials co-design

Solid-state spin defects are promising qubit candidates for quantum network technologies due to their ability to emit single photons, control of their electronic spin states and coupling with nearby nuclear spins as a quantum memory resource. Key requirements include narrow optical linewidths and long spin coherence, all while retaining a beneficial spin-photon interface compatible with long-distance optical fiber networks. We discuss recent advances in studying spin qubits in silicon carbide (SiC) as well as a materials co-design approach to engineer the local spin/host environment guided by computational models to explore new qubit systems. SiC is a commercially available host material with several promising qubits. Recent work highlights the benefits of integrating divacancy (VV⁰) spin qubits in isotopically engineered SiC-based in classical electronic (p-i-n) diode structures for record long electron and nuclear spin coherence [1]. Moreover, the introduction of Vanadium (V⁴⁺) defects in SiC show potential as a bright, O-Band telecom emitter [2]. Further measurements reveal that T₁ relaxation of these V⁴⁺ electron spins are limited primarily by an Orbach phonon relaxation process [3]. Strain-susceptibility measurements indicate a method for suppressing this relaxation via strain-induced modification of low-lying orbital levels [4]. With this in mind, we extend these studies to rare-earth doped oxides, including Er³⁺ doped, epitaxially grown CeO₂ (cerium dioxide) film on Si substrates [5,6], a platform guided by computational predictions. Our results use experimental and computational simulations to explore dominating dephasing processes at milli-Kelvin temperatures [7]. These findings deepen our understanding of defects and materials integration, materials co-design, and advance the fundamental building blocks necessary for a robust and scalable quantum network based on spin-qubits in the solid state.