Near-Surface ^{125}Te^{+} Spins with Millisecond Coherence Lifetime

Area of Science:

• Quantum information science
• Solid-state physics
• Materials science

Background:

• Impurity spins in crystal matrices are crucial for quantum technologies.
• Maintaining spin properties near surfaces is a significant challenge.
• Group-VI ^{125}Te^{+} donors in silicon are potential candidates for microwave-domain applications.

Purpose of the Study:

• To investigate the spin properties of near-surface ^{125}Te^{+} donors in natural silicon.
• To explore methods for controlling the charge and spin states of these near-surface donors.
• To assess the potential of these spins for quantum applications by measuring their coherence and relaxation times.

Main Methods:

• Implantation of ^{125}Te^{+} donors into natural silicon at shallow depths (20 nm).
• Utilizing surface band bending to ionize near-surface Te to the spin-active Te^{+} state.
• Employing optical illumination to further control the Te donor charge state.
• Measuring spin activation yield, spin linewidth, and relaxation (T1) and coherence (T2) times.

Main Results:

• Surface band bending successfully creates spin-active Te^{+} states near the silicon surface.
• Optical illumination provides additional control over the donor charge state.
• A zero-field 3.5 GHz "clock transition" was identified.
• Spin coherence times exceeding 1 ms were achieved, an order of magnitude improvement over other near-surface spin systems.

Conclusions:

• Near-surface ^{125}Te^{+} donors in silicon are viable for quantum technologies.
• Surface ionization and optical control enable manipulation of these spins.
• The extended coherence times demonstrate significant potential for quantum computing and sensing applications.