Hardware & Errors
Qubit Connectivity
The pattern describing which qubits in a processor can directly interact with each other via two-qubit gates.
Definition
Qubit connectivity describes the physical layout determining which pairs of qubits in a quantum processor can directly perform two-qubit gates with each other. Some architectures offer 'all-to-all' connectivity (any qubit can interact with any other), while others are limited to specific neighboring patterns.
Technical Definition
Limited connectivity (like IBM's heavy-hex layout) requires inserting additional 'SWAP' gates to move quantum information between non-adjacent qubits when an algorithm needs them to interact, adding circuit depth and error compared to architectures with native all-to-all connectivity.
Visual Explanation: An Analogy
Think of qubit connectivity like a city's road network — some cities have direct highways connecting every district (all-to-all), while others require navigating through several intermediate neighborhoods to get from one point to another (limited connectivity), adding travel time.
Real-World Use Cases
- A key factor in hardware-aware circuit compilation, discussed in our Research Papers section
- Trapped-ion and QCCD architectures typically offer better native connectivity than fixed 2D superconducting grids