Discovering Quantum Circuits for Logical State Preparation with Deep Reinforcement Learning

Quantum error correction (QEC) is important for the realization of fault-tolerant quantum computers. The first essential step of QEC is to encode the logical state into physical qubits. However, there is no unique recipe for finding a quantum circuit that encodes or prepares the logical state, especially for a given gate set and qubit connectivity. In this work, we use deep reinforcement learning to automatically discover quantum circuits to prepare the logical state of a QEC code given a gate set and qubit connectivity. We show that our method can prepare a logical state of up to $17$ physical qubits code in fully connected qubits and up to $9$ physical qubits code with IBM quantum devices gate set and connectivity with smaller circuit size than other methods.