C2QA Colloquium

Engineering Quantum error correction is usually implemented via an active schedule of discrete error syndrome measurements and adaptive recovery operations which are hardware intensive and prone to introducing and propagating errors. Alternatively, QEC can be realized autonomously and continuously by tailoring dissipation within the quantum system, but it has been an outstanding challenging to obtain the specific form of dissipation to counter prominent physical errors.

In this talk, we will discuss our recent experimental demonstration of autonomous quantum error correction of photon loss, the dominant errors in a superconducting cavity. We encode a logical qubit in Schrödinger cat-like multiphoton states of a superconducting cavity, and realize a corrective dissipation process that directly stabilizes an error syndrome operator: the photon number parity. Implemented with continuous-wave control fields only, this passive protocol boosts the coherence time of the multiphoton qubit by over a factor of two. Notably, QEC is realized in a modest hardware setup with neither high-fidelity readout nor fast digital feedback, in stark contrast to the technological sophistication required for prior QEC demonstrations. We will further discuss the role of dissipation engineering as a resource-efficient alternative or supplement to active QEC in bosonic qubits and logic gates.