To solve problems of practical importance, quantum computers will likely need to incorporate quantum error correction, where a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead typically associated with error correction motivates the search for more hardware-efficient approaches. To this end, in this talk I will describe our recent superconducting circuit experiment realizing a logical qubit memory via the concatenation of encoded bosonic cat qubits with an outer repetition code. The cat qubits are passively protected against bit-flip errors, while phase-flip errors are corrected by the repetition code. The repetition code operates below...