Abstract

Quantum error correction has been successfully applied to enhance the precision of parameter estimation in the presence of noise. Nonetheless, existing methods require a number of noiseless, controllable ancillae and lack efficient encoding and decoding procedures. In this Letter, we demonstrate that subsystem error correction provides a new direction that can substantially simplify the metrological protocol. We derive general conditions under which subsystem stabilizer codes achieve the Heisenberg limit and show that, for broad classes of noise, this can be realized by syndrome-free protocols using at most a single ancilla qubit. Furthermore, we extend this framework to dynamical error correction and show that Floquet codes can protect time-dependent metrological signals in reaching the Heisenberg limit.

About the speaker

Qiushi Liu is a postdoctoral researcher at Perimeter Institute for Theoretical Physics. He earned his PhD in computer science from the University of Hong Kong, supervised by Prof. Yuxiang Yang and Prof. Giulio Chiribella. Prior to that, he obtained a master in physics from ETH Zurich, and bachelor in physics from Peking University. His research interests include quantum metrology, quantum error correction and quantum foundations.