Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
Phys Rev Lett. 2010 Mar 12;104(10):100503. doi: 10.1103/PhysRevLett.104.100503. Epub 2010 Mar 9.
We experimentally demonstrate a quantum walk on a line in phase space using one and two trapped ions. A walk with up to 23 steps is realized by subjecting an ion to state-dependent displacement operations interleaved with quantum coin tossing operations. To analyze the ion's motional state after each step we apply a technique that directly maps the probability density distribution onto the ion's internal state. The measured probability distributions and the position's second moment clearly show the nonclassical character of the quantum walk. To further highlight the difference between the classical (random) and the quantum walk, we demonstrate the reversibility of the latter. Finally, we extend the quantum walk by using two ions, giving the walker the additional possibility to stay instead of taking a step.
我们通过使用一个和两个囚禁离子在相空间中实验演示了量子漫步。通过对离子进行状态相关的位移操作和量子硬币翻转操作的交错，实现了长达 23 步的漫步。为了分析每个步骤后离子的运动状态，我们应用了一种直接将概率密度分布映射到离子内部状态的技术。测量的概率分布和位置的二阶矩清楚地显示了量子漫步的非经典特征。为了进一步突出经典（随机）和量子漫步之间的区别，我们展示了后者的可逆性。最后，我们通过使用两个离子扩展了量子漫步，为漫步者提供了保持而不是迈出一步的额外可能性。
