arXiv subjects

Habitamu Y. Walelign

Publications and source records attributed to Habitamu Y. Walelign.

3 recordsLinked to original sources

arXiv2026

Phase locking nuclear spins in silicon with spin-orbit coupling

Because they have such long coherence times, nuclear spins have extraordinary potential for use in quantum information processing devices. However, coherent nuclear spin control generally requires external phase references, such as microwave control fields. Here, we phase-lock a $^{29}$Si nuclear spin ensemble in a silicon quantum dot using only the internal electronic spin-orbit coupling as a phase reference. When driven with the quantum-dot electrons, the nuclear spins align themselves to a phase determined by the electronic spin-orbit coupling and the timing of the drive protocol. This enables us to measure the coherent precession and inhomogeneous dephasing of the nuclear spins. We corroborate our results with detailed numerical simulations of the many-body electron nuclear system. Our work opens new routes for coherently controlling solid-state nuclear spin ensembles.

quant-ph↗

arXiv2025

The formation of a nuclear-spin dark state in silicon

Silicon-based qubits are often made by trapping individual electrons in quantum dots defined by electric gates. Quantum information can then be stored using the spin states of the electrons. However, the nuclei of the surrounding atoms also have spin degrees of freedom that couple to the electron spin qubits and cause decoherence. The emergence of a nuclear-spin dark state has been predicted to reduce this coupling during dynamic nuclear polarization, when the electrons in the quantum dot drive the nuclei in the semiconductor into a decoupled state. Here, we report the formation of a nuclear-spin dark state in a gate-defined silicon double quantum dot. We show that, as expected, the transverse electron-nuclear coupling rapidly diminishes in the dark state, and that this state depends on the synchronized precession of the nuclear spins. Moreover, the dark state significantly reduces the relaxation rate between the singlet and triplet electronic spin states. This nuclear-spin dark state has potential applications as a quantum memory or in quantum sensing, and might enable increased polarization of nuclear spin ensembles.

cond-mat.mes-hall↗

arXiv2024

Dynamically corrected gates in silicon singlet-triplet spin qubits

Fault-tolerant quantum computation requires low physical-qubit gate errors. Many approaches exist to reduce gate errors, including both hardware- and control-optimization strategies. Dynamically corrected gates are designed to cancel specific errors and offer the potential for high-fidelity gates, but they have yet to be implemented in singlet-triplet spin qubits in semiconductor quantum dots, due in part to the stringent control constraints in these systems. In this work, we experimentally implement dynamically corrected gates designed to mitigate hyperfine noise in a singlet-triplet qubit realized in a Si/SiGe double quantum dot. The corrected gates reduce infidelities by about a factor of three, resulting in gate fidelities above 0.99 for both identity and Hadamard gates. The gate performances depend sensitively on pulse distortions, and their specific performance reveals an unexpected distortion in our experimental setup.

quant-ph↗