Entangling Schrödinger's cat states by seeding a Bell state or swapping the cats

• URL: http://arxiv.org/abs/2406.17999v1
• Date: Wed, 26 Jun 2024 01:04:24 GMT
• Title: Entangling Schrödinger's cat states by seeding a Bell state or swapping the cats
• Authors: Daisuke Hoshi, Toshiaki Nagase, Sangil Kwon, Daisuke Iyama, Takahiko Kamiya, Shiori Fujii, Hiroto Mukai, Shahnawaz Ahmed, Anton Frisk Kockum, Shohei Watabe, Fumiki Yoshihara, Jaw-Shen Tsai,
• Abstract summary: We show that a DV-CV hybrid approach enables us to entangle a pair of Schr"odinger's cat states by two straightforward methods. Our work offers a simple yet powerful application of DV-CV hybridization while also highlighting the scalability of this planar KPO system.
• Score: 0.17708236183599538
• License: http://creativecommons.org/licenses/by-nc-nd/4.0/
• 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. It is increasingly recognized that integrating these two approaches could unlock new potentials, overcoming the inherent limitations of each. Here, we show that such a DV-CV hybrid approach, applied to superconducting Kerr parametric oscillators (KPOs), enables us to entangle a pair of Schr\"odinger's cat states by two straightforward methods. The first method involves the entanglement-preserving and deterministic conversion between Bell states in the Fock-state basis (DV encoding) and those in the cat-state basis (CV encoding). This method would allow us to construct quantum networks in the cat-state basis using conventional schemes originally developed for the Fock-state basis. In the second method, the $\sqrt{\textrm{iSWAP}}$ gate operation is implemented between two cat states following the procedure used for Fock-state encoding. This DV-like gate operation on CV encoding not only completes the demonstration of a universal quantum gate set in a KPO system but also enables faster and simpler gate operations compared to previous SWAP gate implementations on bosonic modes. Our work offers a simple yet powerful application of DV-CV hybridization while also highlighting the scalability of this planar KPO system.

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