In this paper, an improvement for quantum Prisoners’ Dilemma protocol of Eisert-Wilkens-Lewenstein (EWL) is presented. This improvement differs from EWL protocol in that the initial quantum states of Alice and Bob are changeable by themselves. The research results show that when the social optimal initial quantum states are chosen, the payoffs of Alice and Bob from Mixed Strategies at multiple Nash equilibrium are higher than those of EWL protocol. Moreover, with certain payoff matrix and entanglement degree, this improvement can find pure strategy Nash equilibrium where EWL protocol has none.

中文翻译：

---

Eisert-Wilkens-Lewenstein量子囚徒困境协议的改进

在本文中，提出了对 Eisert-Wilkens-Lewenstein (EWL) 的量子囚徒困境协议的改进。这种改进与 EWL 协议的不同之处在于 Alice 和 Bob 的初始量子状态可以自行改变。研究结果表明，选择社会最佳初始量子态，来自多个纳什均衡的混合策略的Alice和Bob的回报高于EWL方案。此外，在一定的支付矩阵和纠缠度下，这种改进可以找到 EWL 协议没有的纯策略纳什均衡。