Also known as any-to-any, all-to-all connectivity denotes the ability to “connect” any qubit to any other qubit. In practice, this means moving our qubits around in space so that any two can be, for example, gated together. All-to-all connectivity comes for “free” with our architecture, while it is nearly impossible for architectures with fixed qubit locations, such as superconducting or NV center.
All-to-all connectivity improves the efficiency and flexibility of quantum computers, eliminating the need for “swap gates” (which add noise), allowing for exotic error correcting codes (which have multiple benefits), and improving the computational power of the quantum processing unit (QPU).
See the benefits of all-to-all connectivity come to life in this scientific paper on Random Circuit Sampling.