No abstract

We present a generalization of the conditional displacement operator, conditioned on a qudit ancilla, and discuss possible implementations. This generalization provides a building block for quantum computation with grid states, allowing efficient error correction protocols.

We find that interactions of coherently-shaped free electrons with photons enable universal quantum computation and error correction with GKP qubits. The electron can entangle multiple GKP qubits, creating GHZ and cluster states.