Trapped Ion MOC

Curated map of Zoo entries in the Trapped Ion family.

Entries

Entry	Type	Status
cirac-zoller-gate	gate	demonstrated
molmer-sorenson-gate	gate	demonstrated
shuttling-ion-trap-qubit	infrastructure	demonstrated
trapped-ion-qubit	qubit	demonstrated
ytterbium-hyperfine-qubit	qubit	demonstrated

Composition

• gate: 2
• infrastructure: 1
• qubit: 2

Conceptual anchors

• motional-mode-coupling-in-ion-traps is the key evergreen note tying the modality to its entangling-gate layer.
• coherence-time-hierarchy is the right lens for comparing long hyperfine memory times to much faster gate and readout cycles.

Curated synthesis

The most useful way to read this family is as a three-layer stack rather than three unrelated notes.

1. trapped-ion-qubit is the modality baseline

   • Start there when the question is why ions are still canonical: identical qubits, minute-scale coherence, high-fidelity readout, and shared-mode connectivity.
   • It owns the broad platform tradeoff against superconducting and neutral-atom systems.

2. cirac-zoller-gate is the historical mechanism note

   • It explains the original phonon-bus idea in its most literal form: map spin information into motion, apply a conditional phase, map back.
   • Read it when the important question is where trapped-ion entangling gates came from conceptually, not which pulse family dominates today.

3. shuttling-ion-trap-qubit is the scaling architecture note

   • It exists because the same shared-motion resource that gives all-to-all connectivity also stops scaling cleanly in very long chains.
   • QCCD is therefore best understood as an architectural response to motional-mode crowding, not as a new qubit modality.

Modern operational stack

• ytterbium-hyperfine-qubit is the memory-and-readout anchor: clock-state storage, fluorescence detection, and long coherence margins.
• molmer-sorenson-gate is the modern entanglement anchor: virtual-phonon XX interactions, robustness beyond the strict Cirac-Zoller ground-state requirement, and pulse shaping toward 99.9%+ two-qubit fidelity.
• Together they expose the practical systems bottleneck: motional-mode engineering and calibration, not the existence of a clean atomic memory.

Gate-to-architecture decision map

The two gate notes and the shuttling note answer different questions. The first two choose how internal states borrow the phonon bus inside one interaction zone; QCCD chooses how many ions should share that bus before routing replaces longer-range collective motion.

Route	How motion is used	Closure condition	What it buys	Dominant systems debt	Read it when…
cirac-zoller-gate	Sequential sideband pulses map a qubit excitation into a real phonon, apply a conditional phase through a second ion and auxiliary level, then map the phonon back	The selected mode must begin near its ground state and end disentangled from both ions	The cleanest literal picture of a phonon as a quantum data bus and the historical route to trapped-ion universality	Ground-state preparation, auxiliary-level control, and sensitivity to heating during a multi-pulse sequence	the question is how the original bus-mediated gate works or why sideband resolution matters
molmer-sorenson-gate	A bichromatic spin-dependent force drives a closed trajectory in motional phase space and leaves an effective XX interaction	Every significantly driven mode must return to its starting phase-space point at the gate end; ground-state cooling is not required, but the Lamb-Dicke and mode-closure conditions remain	The modern operational default: direct entanglement, multi-ion reach, and better tolerance of imperfect motional preparation	Spectator-mode coupling, detuning and phase calibration, heating, and pulse-shape complexity as modes crowd	the question is how present-day ion processors execute high-fidelity entangling gates
shuttling-ion-trap-qubit	Ions are transported between short-chain memory, interaction, and readout zones; a local MS or related gate still supplies entanglement inside each zone	Transport must preserve internal coherence and deliver a sufficiently cold, well-characterized motional state for the next local gate	Keeps local mode spectra tractable while scaling processor connectivity beyond one long Coulomb crystal	Junction routing, scheduling, transport-induced excitation, recooling, and calibration across many zones	the question has shifted from one gate pulse to machine-scale connectivity and throughput

This map prevents two common category errors. MS gates are less sensitive to the initial phonon occupation than Cirac-Zoller gates, but they are not independent of motion: residual phase-space displacement still leaves spin and motion entangled. Likewise, QCCD does not replace the phonon-bus gate; it repeatedly reconstructs a small, controllable local bus after transport. Read all three through motional-mode-coupling-in-ion-traps to track where motional complexity moves rather than assuming it disappears.

Routing rule: when to stay here versus hand off

• Stay in this MOC for the full modality stack: optical and hyperfine encodings, Cirac-Zoller and Mølmer-Sørensen gates, shared motion, and QCCD scaling.
• Enter ytterbium-hyperfine-qubit or molmer-sorenson-gate directly for the modern Yb + MS implementation slice.
• Hand off to neutral-atom-moc when the comparison shifts from Coulomb-crystal buses to tweezer-rearranged atomic arrays with transient Rydberg interactions.

Scope boundary

This is the authoritative trapped-ion platform map. Species-specific entries are reserved for materially distinct encodings or milestones rather than one page per isotope.