Quantum computing is showing great potential to bring computing power to an unprecedented level. However, the standard protocol of quantum error correction uses many qubits and relies on the projective measurement of error syndromes, which often requires a significant resource overhead of hundreds of qubits and feedback controls.
Steven Touzard, a presidential young professor at the National University of Singapore, has been innovating novel approaches to address this issue. The goal of Steven’s research is to use a superconducting platform to store and protect the encoded quantum information from decoherence.
Steven pioneered the experimental investigation of cat-state encoding with both engineered dissipation and Zeno-driven coherent control. For the first time, Steven and collaborators, using superconducting cavities with squeezing and engineered two-photon loss, successfully demonstrated autonomous stabilization of a two-dimensional logical Hilbert space with an exponential suppression of cavity dephasing error.
Another significant contribution by Steven is the quantum error correction of grid states encoding, which is a hardware-efficient bosonic encoding scheme (GKP code). Steven and coworkers ingeniously developed an efficient protocol that uses weak measurement and real-time feedback to effectively implement the stabilization of the logical space for the GKP code, which has led to a new frontier of quantum error correction.
In addition to the experimental achievements, Steven has also made significant contributions to the theoretical development of quantum error correction, such as establishing the theoretical foundation of the autonomous quantum error correction for cat qubits, inventing the pair-cat qubits compatible with full autonomous error correction to suppress excitation loss errors, and bias-preserving gates with stabilized cat qubits.
Steven’s current work at the National University of Singapore focuses on building quantum networks, which can simultaneously offer a way to scale quantum computers towards performing useful tasks, a way to transmit un-hackable information, and a way to improve sensing by connecting quantum sensors.