Entangling Schrödinger's cat states by bridging discrete- and continuous-variable encoding.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39900944.
- Also identified by DOI 10.1038/s41467-025-56503-8 and PMC identifier 11791159.
- Licence recorded as CC BY-NC-ND.
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Abstract
In quantum information processing, two primary research directions have emerged: one based on discrete variables (DV) and the other on the structure of quantum states in a continuous-variable (CV) space. Integrating these two approaches could unlock new potentials, overcoming their respective limitations. Here, we show that such a DV-CV hybrid approach, applied to superconducting Kerr parametric oscillators (KPOs), enables us to entangle a pair of Schrödinger's cat states by two methods. The first involves the entanglement-preserving conversion between Bell states in the Fock-state basis (DV encoding) and those in the cat-state basis (CV encoding). The second method implements a <math xmlns="http://www.w3.org/1998/Math/MathML"> <msqrt><mrow><mi>iSWAP</mi></mrow> </msqrt> </math> gate between two cat states following the procedure for Fock-state encoding. This simple and fast gate operation completes a universal quantum gate set in a KPO system. Our work offers powerful applications of DV-CV hybridization and marks a first step toward developing a multi-qubit platform based on planar KPO systems.