PhD Defense - Kyungjoo Noh

 

Quantum computation and communication are important branches of quantum information science. However, noise in realistic quantum devices fundamentally limits the utility of these quantum technologies. Therefore, quantum error correction (QEC) is essential. Recently, bosonic (or continuous-variable) QEC has risen as a promising hardware-efficient alternative to conventional multi-qubit QEC. In this talk, I will first present the benchmark and optimization results of various single-mode bosonic codes. In particular, I will demonstrate that the GKP codes exhibit excellent, if not optimal, performance against practically relevant excitation loss errors despite the fact that they are not designed to correct loss errors. I will also provide an explanation for why the GKP codes can perform well against loss errors. Next, to address fault-tolerance, I will discuss the concatenation of the GKP code with the surface code (i.e., the surface-GKP code). Specifically, I will show that fault-tolerant bosonic QEC is possible with the surface-GKP code and explain how the additional information from the GKP error correction can significantly boost the performance of the surface code. Lastly, I will briefly discuss various applications of bosonic QEC to quantum communication, sensing, and transduction.