A photonic platform for donor spin qubits in silicon

TL;DR

This paper introduces a silicon-based photonic platform utilizing chalcogen donor impurities for scalable, high-fidelity spin qubits, enabling efficient optical initialization, long coherence times, and potential for multi-qubit coupling in quantum computing.

Contribution

The work demonstrates a novel silicon photonic platform with optically accessible chalcogen donors that enable scalable, high-quality spin qubits without requiring ultra-low temperatures.

Findings

Chalcogen donors emit highly uniform light

Donors can be optically initialized and read out

Long-lived spin ground states at accessible temperatures

Abstract

Donor impurity spins in silicon-28 are highly competitive qubits for upcoming solid-state quantum technologies, yet a proven scalable strategy for multi-qubit devices remains conspicuously absent. These CMOS-compatible, atomically identical qubits offer significant advantages including 3-hour coherence ($T_2$) lifetimes, as well as simultaneous qubit initialization, manipulation and readout fidelities near $\sim\!99.9\%$. These properties meet the requirements for many modern quantum error correction protocols, which are essential for constructing large-scale universal quantum technologies. However, a method of reliably coupling spatially-separated qubits, which crucially does not sacrifice qubit quality and is robust to manufacturing imperfections, has yet to be identified. Here we present such a platform for donor qubits in silicon, by exploiting optically-accessible `deep' chalcogen donors. We show that these donors emit highly uniform light, can be optically initialized, and offer long-lived spin qubit ground states without requiring milliKelvin temperatures. These combined properties make chalcogen donors uniquely suitable for incorporation into silicon photonic architectures for single-shot single-qubit readout as well as for multi-qubit coupling. This unlocks clear pathways for silicon-based quantum computing, spin to photon conversion, photonic memories, silicon-integrated triggered single photon sources and all-optical silicon switches.