Transmon-mediated gates on GKP qubits in superconducting circuits – Part 2

Bosonic codes, such as GKP codes, encode quantum information in the states of an oscillator. By taking advantages of the redundancy in a single physical system, they offer a hardware-efficient route for fault-tolerant quantum computing [1]. To this end, apart from error-corrected performance as a quantum memory [2], we require a set of single- and two-qubit gates on the encoded GKP qubits. In our architecture based on superconducting circuits, we utilize an auxiliary transmon qubit to perform gates on the logical information stored in the microwave-frequency cavity [3]. The implementation leverages universal control over the auxiliary qubit and the echoed conditional displacement gate to manipulate the GKP-qubit information. In the second part of this talk, we present experimental demonstrations of single and two-qubit gates on GKP qubits.

[1] M. Lemonde et al., arXiv : 2409.05813 (2024).

[2] D. Lachance-Quirion et al., Phys. Rev. Lett. 132, 150607 (2024).

[3] Singh S. (2023, November 12). 4.7 Shraddha Singh [Video]. YouTube. https://www.youtube.com/watch?v=2DRORDLQWsk