论文标题
用于确定量子纠缠的受控掉期测试
The controlled SWAP test for determining quantum entanglement
论文作者
论文摘要
量子纠缠对于开发量子计算，通信和技术至关重要。可控的掉期测试广泛用于状态比较，可以适应纯状态的有效且有用的测试。在这里，我们表明该测试可以证明纠缠的存在（并且是真正的N Qubit纠缠），可以区分纠缠类别，并且两量态状态的同意与测试的输出概率有关。我们还提出了一种对N Qubit状态类似的纠缠的多部分措施。检测纠缠所需的副本数量减少了较大的系统，对于最大纠缠状态的许多（n> 8）量子平均为4。对于非最大程度的纠缠状态，检测纠缠所需的测试状态的平均副本数量随着纠缠的减少而增加。此外，当将典型的小误差引入正在研究的州时，结果是可靠的。
Quantum entanglement is essential to the development of quantum computation, communications, and technology. The controlled SWAP test, widely used for state comparison, can be adapted to an efficient and useful test for entanglement of a pure state. Here we show that the test can evidence the presence of entanglement (and further, genuine n-qubit entanglement), can distinguish entanglement classes, and that the concurrence of a two-qubit state is related to the test's output probabilities. We also propose a multipartite measure of entanglement that acts similarly for n-qubit states. The number of copies required to detect entanglement decreases for larger systems, to four on average for many (n>8) qubits for maximally entangled states. For non-maximally entangled states, the average number of copies of the test state required to detect entanglement increases with decreasing entanglement. Furthermore, the results are robust to second order when typical small errors are introduced to the state under investigation.
