Shuttling Ion-Trap Qubit (QCCD)

Description

QCCD-style trapped-ion architectures scale by physically transporting ions between segmented trap zones: memory, interaction, and readout regions. Rather than keeping very long ion chains (which suffer mode crowding), shuttling keeps chains short and composes operations through transport.

Figure

Hamiltonian

Each interaction zone follows standard trapped-ion Hamiltonians; shuttling adds time-dependent trap potentials:

$H(t)={\sum }_i\left[\frac{p_i^2}{2m}+V_i(x_i,t)\right]+H_{\text{int}}$

with $V_i(x,t)$ engineered to keep motional excitation low during transport.

Motivation

QCCD shuttling addresses the core scaling problem of trapped-ion systems: long chains become difficult to control due to mode crowding and transport bottlenecks. Segmented transport allows architectures to keep local interaction zones small while scaling globally through movement, routing, and scheduling.

Key Findings

• High-fidelity ion transport through multi-zone junctions has been demonstrated.
• Practical performance is dominated by transport-induced heating and scheduler quality.
• QCCD naturally supports memory/interaction/readout zone specialization.
• This architecture is central to many trapped-ion fault-tolerance roadmaps.

Key Metrics

Metric	Value	Notes	Fidelity reference
Transport speed	10–100 μs / hop	Device dependent	—
Added motional excitation	<1 phonon (optimized)	Key transport quality metric	—
2Q gate fidelity	99%+	In interaction zones	Moses et al. 2023
Main scaling bottleneck	transport scheduling + heating	architecture-level challenge	—

Linked Papers

• kielpinski-2002-shuttling

Related Entries

• trapped-ion-qubit
• cirac-zoller-gate