Zhang Xiang, Shen Yangchao, Zhang Junhua, Casanova Jorge, Lamata Lucas, Solano Enrique, Yung Man-Hong, Zhang Jing-Ning, Kim Kihwan
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China.
Institut für Theoretische Physik, Universität Ulm, Albert-Einstein-Allee 11, Ulm D-89069, Germany.
Nat Commun. 2015 Aug 4;6:7917. doi: 10.1038/ncomms8917.
A quantum simulator is an important device that may soon outperform current classical computations. A basic arithmetic operation, the complex conjugate, however, is considered to be impossible to be implemented in such a quantum system due to the linear character of quantum mechanics. Here, we present the experimental quantum simulation of such an unphysical operation beyond the regime of unitary and dissipative evolutions through the embedding of a quantum dynamics in the electronic multilevels of a (171)Yb(+) ion. We perform time reversal and charge conjugation, which are paradigmatic examples of antiunitary symmetry operators, in the evolution of a Majorana equation without the tomographic knowledge of the evolving state. Thus, these operations can be applied regardless of the system size. Our approach offers the possibility to add unphysical operations to the toolbox of quantum simulation, and provides a route to efficiently compute otherwise intractable quantities, such as entanglement monotones.
量子模拟器是一种重要的设备，可能很快就会超越当前的经典计算。然而，由于量子力学的线性特性，一种基本的算术运算——复共轭，被认为在这样的量子系统中无法实现。在这里，我们通过将量子动力学嵌入到（171）Yb（+）离子的电子多能级中，展示了在幺正和耗散演化范围之外对这种非物理运算的实验量子模拟。我们在没有演化态断层成像知识的情况下，对马约拉纳方程的演化执行时间反演和电荷共轭，它们是反幺正对称算符的典型例子。因此，这些运算可以在不考虑系统大小的情况下应用。我们的方法为在量子模拟工具箱中添加非物理运算提供了可能性，并为有效计算诸如纠缠单调量等原本难以处理的量提供了一条途径。
