Qubit ZooCurated map of Zoo entries in the Majorana / Topological family.
Entries
| Entry | Type | Status |
|---|---|---|
| majorana-topological-qubit | qubit | proposed |
| planar-josephson-junction-qubit | qubit | proposed |
| tetron-qubit | qubit | proposed |
Composition
- qubit: 3
Three-layer map
- majorana-topological-qubit is the physics-layer note: nonlocal fermion-parity encoding, Majorana zero modes, and the requirement that splitting fall exponentially with separation.
- planar-josephson-junction-qubit is the fabrication-layer route: a lithographically defined InAs/Al-style junction where spin-orbit-coupling-for-qubit-control and phase bias near create a tunable topological channel.
- tetron-qubit is the architecture-layer proposal: four Majorana modes arranged for parity measurement and measurement-only braiding, with the long-term promise judged against threshold-theorem rather than spectroscopy alone.
What unifies this family
Topological notes in the Zoo should read as a stack, not as three unrelated devices. The common claim is hardware-level error suppression from nonlocal parity encoding, but the practical bottleneck is still the same divincenzo-criteria scorecard as everywhere else: prepare a protected state, read parity reliably, and execute entangling operations before quasiparticle poisoning or mode overlap erases the advantage.
Protection-claim ladder
The easiest way to misread this family is to collapse three different claim levels into one bucket called “topological qubit.”
- majorana-topological-qubit is the protection primitive: the important content is nonlocal fermion parity, end-mode splitting, and the evidence ladder from spectroscopy to controllable parity.
- planar-josephson-junction-qubit is the materials-platform route: it asks whether a lithographic Josephson geometry can reliably enter the topological regime at all.
- tetron-qubit is the computing architecture claim: four Majorana modes in a fixed-parity layout, repeated parity measurements, and the possibility of turning protection into an actual logical resource.
A useful guardrail is that a two-end-mode device can demonstrate the ingredients of topological protection without yet constituting a full logical qubit. In this family, the graph should climb from topological-channel evidence, to parity control, to fixed-parity four-mode encoding, and only then to protected computational primitives judged against divincenzo-criteria and threshold-theorem.
Boundary-case routing table
| Entry | Why it stays in topological-moc | What nearby family it can be confused with |
|---|---|---|
| majorana-topological-qubit | the core claim is nonlocal fermion-parity encoding with exponentially suppressed mode overlap, even before a full four-mode computational encoding is assembled | super-semi-moc shares the same InAs/Al language, but not the topological-protection claim |
| planar-josephson-junction-qubit | phase-biased Josephson geometry is being used to open a topological channel, not just to tune a qubit frequency | super-semi-moc if the junction is being discussed as an electrostatically tunable weak link rather than a topological medium |
| tetron-qubit | the device is an architecture for repeated parity measurements and measurement-only braiding built on Majorana ingredients | cross-platform-moc at the systems level, because its real payoff is lower logical overhead if the physical protection holds |
Boundary with the super-semi family
The materials overlap with super-semi-moc on purpose, especially around InAs/Al weak links and Josephson geometries, but the classification hinge is different. A note belongs in this Majorana / Topological branch when the qubit claim depends on entering a topological superconducting regime and protecting information in nonlocal fermion parity. If the same hybrid hardware is being used mainly for gate-tunable Josephson physics, Andreev control, or protected-circuit engineering without a topological phase claim, it belongs in super-semi-moc instead.
A useful mental check is: if removing the words “topological phase” or “nonlocal parity” would leave the note conceptually intact, it probably is not a topological-family note.
Reading order
If you want the shortest conceptual path through this family, start with majorana-topological-qubit for the protection mechanism, then planar-josephson-junction-qubit for the scalable materials platform, and finish with tetron-qubit for the control architecture that tries to turn those ingredients into a computable qubit.