Electron spin coherence of shallow donors in natural and isotopically enriched germanium

Abstract

Germanium is a widely used material for electronic and optoelectronic devices and recently it has become an important material for spintronics and quantum computing applications. Donor spins in silicon have been shown to support very long coherence times ($T_2$) when the host material is isotopically enriched to remove any magnetic nuclei. Germanium also has non-magnetic isotopes so it is expected to support long $T_2$s while offering some new properties. Compared to Si, Ge has a strong spin-orbit coupling, large electron wavefunction, high mobility, and highly anisotropic conduction band valleys which will all give rise to new physics. In this Letter, the first pulsed electron spin resonance (ESR) measurements of $T_2$ and the spin-lattice relaxation ($T_1$) times for ${}^{75}$As and ${}^{31}$P donors in natural and isotopically enriched germanium are presented. We compare samples with various levels of isotopic enrichment and find that spectral diffusion due to ${}^{73}$Ge nuclear spins limits the coherence in samples with significant amounts of ${}^{73}$Ge. For the most highly enriched samples, we find that $T_1$ limits $T_2$ to $T_2=2T_1$. We report an anisotropy in $T_1$ and the ensemble linewidths for magnetic fields oriented along different crystal axes but do not resolve any angular dependence to the spectral-diffusion-limited $T_2$ in samples with ${}^{73}$Ge.

References in corpus (1)

• An experimental demonstration of room-temperature spin transport in n-type Germanium epilayers

Cited by in corpus (17)

• The germanium quantum information route
• Gate-controlled quantum dots and superconductivity in planar germanium
• Ballistic supercurrent discretization and micrometer-long Josephson coupling in germanium
• Giant g factor tuning of long-lived electron spins in Ge
• Carrier and Spin Coherent Dynamics in Strained Germanium-Tin Semiconductor on Silicon
• Probing resonating valence bonds on a programmable germanium quantum simulator
• All-electrical control of hole singlet-triplet spin qubits at low leakage points
• Large Stark tuning of donor electron spin quantum bits in germanium
• Exchange interaction of hole-spin qubits in double quantum dots in highly anisotropic semiconductors
• Measurement of tunnel coupling in a Si double quantum dot based on charge sensing
• A two-dimensional 10-qubit array in germanium with robust and localised qubit control
• Theory of single and two-qubit operations with donor-bound electron spins in germanium
• Robust entangling gate for capacitively coupled few-electron singlet-triplet qubits
• Landau levels and shallow donor states in GaAs/AlGaAs multiple quantum wells at mega-gauss magnetic fields
• Nonequilibrium topological spin textures in momentum space
• Donors in Ge as Qubits: Establishing Physical Attributes
• Andreev spin qubit protected by Franck-Condon blockade