We propose a method for transferring quantum entangled states of two photonic cat-state qubits (cqubits) from two microwave cavities to the other two microwave cavities. This proposal is realized by using four microwave cavities coupled to a superconducting flux qutrit. Because of using four cavities with different frequencies, the inter-cavity crosstalk is significantly reduced. Since only one coupler qutrit is used, the circuit resource is minimized. The entanglement transfer is completed with a singlestep operation only, thus this proposal is quite simple. The third energy level of the coupler qutrit is not populated during the state transfer, therefore decoherence from the higher energy level is greatly suppressed. Our numerical simulations show that high-fidelity transfer of two-cqubit entangled states from two transmission line resonators to the other two transmission line resonators is feasible with current circuit QED technology. This proposal is universal and can be applied to accomplish the same task in a wide range of physical systems, such as four microwave or optical cavities, which are coupled to a natural or artificial three-level atom.

中文翻译：

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在电路QED中传输光子猫态量子位的纠缠态

我们提出了一种将两个光子猫态量子位（cqubits）从两个微波腔传递到另外两个微波腔的量子纠缠态的方法。通过使用四个与超导通量qutrit耦合的微波腔体来实现该建议。由于使用了四个具有不同频率的空腔，因此大大降低了空腔之间的串扰。由于仅使用一个耦合器Qutrit，因此电路资源被最小化。纠缠转移仅需一步操作即可完成，因此该建议非常简单。在状态转移期间不会填充耦合器qutrit的第三能级，因此大大抑制了与较高能级的相干性。我们的数值模拟表明，两立方比特的高保真传输利用电流电路QED技术，从两个传输线谐振器到另外两个传输线谐振器的纠缠状态是可行的。该建议是通用的，可以应用于在广泛的物理系统中完成相同的任务，例如与自然或人工三能级原子耦合的四个微波或光学腔。