论文标题
概率存储和Qubit相门的检索
Probabilistic storage and retrieval of qubit phase gates
论文作者
论文摘要
对于用作量子存储器的系统数量，概率的存储和统一量子动力学的检索（PSR）是可能的[PRL 122，170502（2019）]。在这里，由于对要存储的统一转换的先验知识，我们研究了改进。特别是，我们研究$ n \ rightarrow 1 $ QUBIT相位门的PSR，即具有未知角度的圆形$ Z $轴，并表明，如果我们仅访问Gate，则仅访问$ n $ n $ times，则可以完美检索其一次性的最佳概率是$ n/（n/（n+1）$。我们为最佳协议提出了一个量子电路实现，并表明可编程相位门[PRL 88，047905（2002）]可以变成$（2^k-1）\ rightarrow 1 $相位门的最佳PSR，并且仅需要$ k $ cnot门，而在$ k $中具有指数为小的失败概率。
Probabilistic storage and retrieval (PSR) of unitary quantum dynamics is possible with exponentially small failure probability with respect to the number of systems used as a quantum memory [PRL 122, 170502 (2019)]. Here we study improvements due to a priori knowledge about the unitary transformation to be stored. In particular, we study $N \rightarrow 1$ PSR of qubit phase gates, i.e. qubit rotations a round $Z$ axis with an unknown angle, and show that if we access the gate only $N$-times, the optimal probability of perfect retrieving of its single use is $N/(N+1)$. We propose a quantum circuit realization for the optimal protocol and show that programmable phase gate [PRL 88, 047905 (2002)] can be turned into $(2^k-1)\rightarrow 1$ optimal PSR of phase gates and requires only $k$ CNOT gates, while having exponentially small failure probability in $k$.
