Super-Semi MOC

Curated map of Zoo entries in the Super-Semi family.

Entries

Entry	Type	Status
all-semiconductor-superconducting-qubit	qubit	proposed
andreev-pair-qubit	qubit	demonstrated
andreev-spin-qubit	qubit	demonstrated
ferbo-qubit	qubit	proposed
gatemon	qubit	demonstrated
gatemonium	qubit	demonstrated

Composition

• qubit: 6

Conceptual anchors

• josephson-junction-as-nonlinear-element is the shared superconducting backbone, even when the weak link is semiconductor-defined rather than oxide-barrier-defined.
• spin-orbit-coupling-for-qubit-control is the key separator between purely gate-tunable Josephson devices and spin-active Andreev hybrids.
• charge-noise-sweet-spot is the right lens for comparing how much electrical tunability each architecture gains without paying too much dephasing cost.
• noise-bias-and-asymmetric-error-channels is the extra routing note for the protection-first branch, where the claim is not just “higher coherence” but a deliberately skewed error channel.

Curated synthesis

The cleanest way to read this family is to ask where the semiconductor is doing the conceptual work. The same InAs/Al or group-IV vocabulary can mean three very different things.

1. Semiconductor as a tunable Josephson knob

   • gatemon is the minimal case: transmon logic survives, but the weak link makes $E_J$ electrically tunable.
   • gatemonium is the protected-circuit extension of the same move: the weak link still tunes the Josephson element, but now inside a fluxonium-style inductive circuit where gate control moves the device between different protection regimes.
   • Read this branch primarily through josephson-junction-as-nonlinear-element and charge-noise-sweet-spot, not through spin language.

2. Semiconductor as part of the qubit subspace itself

   • andreev-pair-qubit uses the even-parity empty/doubly occupied Andreev states; its microwave transition is controlled by superconducting phase and weak-link transmission.
   • andreev-spin-qubit uses spin-split Andreev levels as the qubit degree of freedom, so spin-orbit physics and parity stability are the central story rather than side constraints.
   • ferbo-qubit pushes further into the protection-first regime: the Andreev sector is part of the mechanism that suppresses relaxation before error correction, which is why it belongs adjacent to noise-bias-and-asymmetric-error-channels as well as to superconducting protected-circuit notes.
   • This branch should feel closer to “engineered weak-link quantum states” than to ordinary tunable transmons.

3. Semiconductor as the full materials stack

   • all-semiconductor-superconducting-qubit is the fabrication-endpoint branch. Its main claim is not a new control Hamiltonian but the possibility of moving the entire superconducting circuit, junctions included, inside one doped crystal.
   • Compare it to gatemon or transmon on interface elimination and process integration, and to kane-qubit on atomic-precision fabrication lineage.

Semiconductor-superconductor routing table

Entry	Keep it in super-semi-moc when the main claim is…	Hand off when the real question becomes…
gatemon	electrostatic tuning of an otherwise transmon-like Josephson element	ordinary circuit-QED scaling or baseline superconducting benchmarking in superconducting-moc
gatemonium	a gate-tunable weak link reshaping which fluxonium regime the same circuit can access	protected-circuit comparison against fluxonium, heavy-fluxonium-qubit, or 0-pi-qubit inside superconducting-moc
andreev-spin-qubit	odd-parity Andreev states and spin-dependent supercurrent are the qubit resource	nonlocal parity encoding or a topological phase claim in topological-moc
andreev-pair-qubit	even-parity Andreev pair states and phase-dependent weak-link spectroscopy are the resource	ordinary Josephson-circuit scaling in superconducting-moc
ferbo-qubit	even-parity Andreev structure is being used as a relaxation-bias / protection mechanism inside a fluxonium-like circuit	the comparison becomes purely protected-circuit taxonomy in superconducting-moc or topological parity protection in topological-moc
all-semiconductor-superconducting-qubit	monolithic crystal growth and interface elimination are the conceptual novelty	donor-style atomic fabrication lineage in semiconducting-moc or ordinary superconducting-circuit performance in superconducting-moc

Weak-link participation ladder

The semiconductor weak link can enter the qubit at three different depths: as a tunable circuit coefficient, as the microscopic two-level system, or as one half of a deliberately hybridized protected mode. That distinction is more useful than grouping every device by material stack alone.

Branch	Where the computational state primarily lives	Role of Andreev occupation / parity	Main control and readout layer	Failure mode that must stay visible
gatemon	The collective charge-phase mode of a transmon-like circuit	The weak-link spectrum is folded into $U_J(\phi ;V_g)$ while the junction is assumed to remain on its even-parity ground branch; parity is not the encoding	Gate voltage tunes the junction; ordinary circuit-QED drive and dispersive readout operate the qubit	Gate noise, hysteresis, and junction-intrinsic loss can erase the benefit of voltage tunability; accidental weak-link occupation appears as instability rather than a logical operation
gatemonium	Fluxonium-like plasmon / fluxon modes set by $E_C$, $E_L$, external flux, and the gate-tuned weak-link potential	Andreev channel transparencies reshape the nonlinear potential, but the demonstrated device does not encode information in a chosen quasiparticle-parity manifold	Gate control of $E_J$ is combined with flux bias and circuit-QED spectroscopy / control	Array inductive loss, nonsinusoidal weak-link calibration, and gate-noise susceptibility must be separated from the ideal fluxonium sweet-spot story
andreev-pair-qubit	The two even-parity states of one Andreev doublet	The logical transition changes pair occupation while remaining in the even sector; a parity switch leaves that computational manifold	Phase-dependent microwave and cavity coupling address the pair transition	Quasiparticle trapping, parity switching, and relaxation out of the selected doublet are first-class state-lifecycle errors
andreev-spin-qubit	The spin-split odd-parity states of one trapped quasiparticle	A fixed odd-parity sector is the prerequisite for the spin qubit; spin-dependent supercurrent supplies the readout signal	Spin-orbit-enabled control plus dispersive sensing of the junction response	Quasiparticle poisoning changes the parity sector, while spin relaxation and single-shot-readout fidelity remain separate bottlenecks
ferbo-qubit	A proposed hybrid of one bosonic fluxonium-like mode and an even-parity Andreev pseudospin	Disjoint support in the Andreev degree of freedom is intended to suppress selected bosonic relaxation matrix elements; the fermionic sector is part of the protection mechanism	High-transmission weak-link engineering and a zero-flux operating point define the protected regime	The predicted bias must still survive experimental state preparation, parity stability, high-impedance fabrication, and readout

Use this ladder to avoid calling every fixed-parity condition “parity protection.” In andreev-pair-qubit and andreev-spin-qubit, parity stability is primarily a prerequisite that keeps the device inside its chosen computational sector. In ferbo-qubit, structure within the even-parity Andreev space is proposed to suppress a particular relaxation matrix element, which is a stronger but still theory-stage claim. Read that final row through noise-bias-and-asymmetric-error-channels rather than treating it as generic immunity, and use divincenzo-criteria to keep preparation and readout evidence separate from Hamiltonian protection.

Routing rule inside the family

• Start with gatemon or gatemonium when the interesting question is what electrostatic control does to an otherwise familiar superconducting circuit.
• Start with andreev-spin-qubit or ferbo-qubit when the weak link’s internal spin, parity, or Andreev structure is the qubit resource or the protection mechanism.
• Start with all-semiconductor-superconducting-qubit when the value proposition is monolithic fabrication or interface elimination rather than a mature coherence result.
• For the non-hybrid dot and donor branch of the same broader materials ecosystem, continue in semiconducting-moc.

Boundary with the superconducting family

This family shares a lot of vocabulary with superconducting-moc, especially around Josephson elements, circuit-QED readout, and sweet-spot language, but the routing rule is simple: stay here only when the semiconductor weak link is doing conceptual work. gatemon and gatemonium belong here because gate-tunable junction physics is the point, and andreev-spin-qubit / ferbo-qubit belong here because Andreev-level and parity structure enter the qubit itself. If the main story is instead protected-circuit geometry, bosonic encoding, or ordinary superconducting coherence scaling, route back to superconducting-moc even when the fabrication stack overlaps.

Boundary with the topological family

This family shares hardware vocabulary with topological-moc such as InAs/Al heterostructures, Josephson weak links, and strong spin-orbit coupling, but it makes a different promise. gatemon, andreev-spin-qubit, and ferbo-qubit stay here because their value comes from tunability, Andreev structure, or circuit-level protection inside an otherwise conventional control stack. Once the central claim becomes nonlocal parity encoding or a phase-biased topological channel that is supposed to suppress errors before code overhead, route the reader to topological-moc instead.

Scope boundary

This facet is about hybridization, not mere material substitution: the semiconductor must change the circuit physics, control surface, or protection story.