Quantum computers are extremely vulnerable to external noise sources. Therefore, to realize a large-scale quantum computer capable of performing useful computations, one needs to actively correct errors before they accumulate. This process is known as quantum error correction. To be able to perform quantum error correction at all, one needs to design suitable quantum bits. One promising proposal is to encode each quantum bit into the continuous variables of a quantum harmonic oscillator, such as an optical or microwave field mode or the motion of a trapped particle. In this direction, the Gottesman-Kitaev-Preskill (GKP) encoding is considered particularly promising, as it allows for efficient quantum error correction against relevant noise sources, while also enabling easy manipulation of the encoded quantum information. However, the GKP encoding requires a special type of resource, called GKP states or grid states, which has proven challenging to realize experimentally. Therefore, the quality of GKP states demonstrated so far is insufficient for effective quantum error correction. In this work, we propose a novel GKP state generation scheme which circumvents some of the technical limitations of previous protocols. Our scheme thus enables the preparation of high quality GKP states, suitable for quantum error correction with currently available state-of-the-art technologies.
The work was carried out in collaboration with professor Radim Filip from Palcký University, Czech Republic. The work is available at :
https://www.nature.com/articles/s41534-020-00353-3