Spin-Photon MOC

Curated map of Zoo entries in the Spin-Photon family.

Entries

Entry	Type	Status
nv-center-qubit	qubit	demonstrated
rare-earth-ion-qubit	qubit	demonstrated
silicon-carbide-defect-qubit	qubit	demonstrated
siv-color-center-qubit	qubit	demonstrated
t-center-qubit	qubit	demonstrated

Composition

• qubit: 5

Conceptual anchors

• divincenzo-criteria criteria 6 and 7 organize this family more cleanly than gate-centric comparisons, because every note here is really about turning a local spin memory into a networkable module.
• coherence-time-hierarchy captures the main engineering cost of those cleaner optical interfaces: spectral quality, cryogenic burden, and memory lifetime move together rather than independently.
• spin-photon-interfaces-separate-emission-collection-and-wavelength-matching is the family-level interface router: it separates intrinsic emission quality, collection into a controlled mode, and wavelength compatibility with the deployed link instead of collapsing them into one generic “optical interface” score.
• quantum-transduction is a useful boundary note: platforms here are most interesting when they reduce or avoid transduction pain by emitting photons that are already spectrally useful for networking.
• Keep resonant optical-cavity enhancement on the optical branch mapped by spin-photon-interfaces-separate-emission-collection-and-wavelength-matching, rather than routing it through microwave circuit-QED notes: rare-earth-ion-qubit and siv-color-center-qubit use nanophotonic cavities to enhance emission and collection, not the off-resonant lifetime-protection mechanism described by purcell-protection-via-detuning.

Curated synthesis

This family is best read as the network-emitter-optimized descendant branch of the broader defect-spin story.

1. siv-color-center-qubit is the optical-quality-first branch

   • Group-IV vacancy centers buy much cleaner photons than NV by using inversion symmetry to suppress electric-field sensitivity.
   • The price is cryogenic severity: SiV offers excellent optical coherence but drags in a harsher phonon-temperature constraint, while SnV eases that constraint at the cost of a less mature platform.

2. t-center-qubit is the telecom-and-integration-first branch

   • The central claim is not just “another defect spin,” but “a spin-photon node already living in silicon and already emitting in the telecom O-band.”
   • Route here when silicon-photonics compatibility, fibre-network realism, or modular distributed-computing fit matters more than diamond-emitter maturity.

3. The family-level comparison is about which systems burden you want to pay

   • SiV/SnV pay heavily in temperature to buy cleaner optical lines and nanophotonic performance.
   • T centers pay in platform maturity and benchmark depth, but may save substantial systems complexity by starting inside silicon and near telecom wavelengths.
   • silicon-carbide-defect-qubit trades some emitter uniformity for wafer-scale wide-bandgap processing and a broad defect palette.
   • rare-earth-ion-qubit is the long-memory and spectral-multiplexing branch: Er supplies native C-band photons, while Yb nanophotonic nodes have demonstrated multiplexed remote entanglement.

4. This MOC should usually be read against color-center-moc, not in isolation

   • The useful contrast is not “which color center is best?” but “when does a defect stop being primarily a local-spin story and become primarily a network-emitter story?”
   • nv-center-qubit remains the better anchor for room-temperature local-memory maturity, while this page owns the branch where optical interface quality is the main selection criterion.

Node-stack comparison

A spin-photon platform is not selected by one record number. A useful node must preserve a local state, emit a usable photon, survive the fibre stack, and expose enough parallelism to overcome heralding loss. The five entries place their strongest asset—and their remaining systems debt—at different layers of that chain.

Branch	Strongest node asset	Photon / network route	Bottleneck that still dominates
nv-center-qubit	Most mature electron-plus-nuclear register, including room-temperature local control	637-nm emission with a weak zero-phonon fraction; long links usually need aggressive collection engineering and wavelength conversion	Optical collection, spectral stability, and the gap between excellent local memory and efficient remote entanglement
siv-color-center-qubit	Inversion-symmetric, high-ZPL optical interface with strong nanophotonic performance	Clean visible / near-visible photons are cavity friendly, but deployed telecom links still add a conversion layer	Phonon-limited spin coherence, especially for SiV, plus the temperature and diamond-fabrication burden
t-center-qubit	Electron-plus-nuclear register inside a silicon-photonics-compatible host	Native 1326-nm O-band emission removes much of the wavelength-conversion burden	Device yield, spectral uniformity, and benchmark maturity compared with diamond emitters
silicon-carbide-defect-qubit	Room-temperature defect-spin control and nuclear registers in a wafer-scale wide-bandgap platform	Near-infrared spin-photon interfaces can be integrated in SiC waveguides, but are not automatically telecom-native	Transform-limited optical stability and reproducible cavity-coupled single-defect yield across a fragmented defect landscape
rare-earth-ion-qubit	Exceptionally long spin memories plus intrinsic spectral multiplexing	Er supplies native C-band photons; other useful species trade that advantage for different memory and optical properties	Weak 4f oscillator strength makes cavity enhancement essential, while deterministic local multi-ion gates remain immature

Read the columns in order. coherence-time-hierarchy tests whether the local memory survives the heralding cycle. spin-photon-interfaces-separate-emission-collection-and-wavelength-matching then separates the optical-interface budget into emission, collection, and link matching: siv-color-center-qubit anchors high-ZPL cavity coupling, rare-earth-ion-qubit anchors cavity enhancement of weak 4f transitions, and silicon-carbide-defect-qubit or t-center-qubit expose integrated waveguide/cavity yield. Finally, quantum-transduction prices any wavelength mismatch that remains between the emitted photon and the deployed link.

Do not substitute purcell-protection-via-detuning or resonator-as-quantum-bus for that middle layer. Those Evergreens describe off-resonant microwave cavity coupling in circuit QED—respectively suppressing cavity-mediated decay and mediating virtual qubit exchange—whereas these spin-photon nodes generally seek resonant optical Purcell enhancement and efficient photon extraction. Keeping that boundary explicit prevents a shared word, “cavity,” from collapsing two different physical jobs.

This reading order keeps a native-telecom advantage distinct from a clean-emitter advantage: SiV can win the local optical interface while T centers or Er reduce the downstream fibre burden.

Routing rule

• Read this MOC when the primary question is how to build a better spin-to-photon interface, not how to get the most mature defect-spin qubit overall; use spin-photon-interfaces-separate-emission-collection-and-wavelength-matching when that comparison needs to be decomposed into emission, collection, and link matching.
• Hand back to color-center-moc when room-temperature operation, ODMR-style control, or local defect-spin memory maturity becomes the main criterion.
• Use quantum-transduction as the downstream systems check: if a platform already emits where the network wants to live, that is a real architectural advantage, not just a spectroscopy detail.
• Treat siv-color-center-qubit and t-center-qubit as complementary answers to different network bottlenecks, not as a simple maturity ladder.