Xu-Ke Gu

Deterministic generation and tomography of a macroscopic Bell state between a millimeter-sized spin system and a superconducting qubit

  1. Da Xu,
  2. Xu-Ke Gu,
  3. Yuan-Chao Weng,
  4. He-Kang Li,
  5. Yi-Pu Wang,
  6. Shi-Yao Zhu,
  7. and J. Q. You
Entanglement is a fundamental property in quantum mechanics that systems share inseparable quantum correlation regardless of their mutual distances. Owing to the fundamental significance
and versatile applications, the generation of quantum entanglement between {\it macroscopic} systems has been a focus of current research. Here we report on the deterministic generation and tomography of the macroscopically entangled Bell state in a hybrid quantum system containing a millimeter-sized spin system and a micrometer-sized superconducting qubit. The deterministic generation is realized by coupling the macroscopic spin system and the qubit via a microwave cavity. Also, we develop a joint tomography approach to confirming the deterministic generation of the Bell state, which gives a generation fidelity of 0.90±0.01. Our work makes the macroscopic spin system the largest system capable of generating the maximally entangled quantum state.
arxiv pdf