Polarimetry with Spins in the Solid State.

Peri, Lorenzo; von Horstig, Felix-Ekkehard; Barraud, Sylvain; Ford, Christopher J B; Benito, Mónica; Gonzalez-Zalba, M Fernando · Nano Lett · 2025

basic_science · Level V

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Abstract

The ability for optically active media to rotate the polarization of light is the basis of polarimetry, a prominent technique responsible for many breakthroughs in fields as varied as astronomy, medicine, and material science. Here, we recast the primary mechanism for spin readout in semiconductor-based quantum computers, Pauli spin-blockade (PSB), as the natural extension of polarimetry to the third dimension. We perform polarimetry with spins through a silicon quantum dot exchanging a hole with a boron acceptor, demonstrating the role of spin-orbit coupling in creating spin misalignment. Perfect spin alignment may be recovered by means of rotating the applied magnetic-field orientation. This work shows how spin misalignment sets a fundamental upper limit for the spin readout fidelity in quantum-computing systems based on PSB.