Robens Carsten, Alt Wolfgang, Emary Clive, Meschede Dieter, Alberti Andrea
1Institut Für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany.
2Joint Quantum Centre Durham-Newcastle, Newcastle University, Newcastle upon Tyne, NE1 7RU UK.
Appl Phys B. 2017;123(1):12. doi: 10.1007/s00340-016-6581-y. Epub 2016 Dec 19.
Elitzur and Vaidman have proposed a measurement scheme that, based on the quantum superposition principle, allows one to detect the presence of an object-in a dramatic scenario, a bomb-without interacting with it. It was pointed out by Ghirardi that this interaction-free measurement scheme can be put in direct relation with falsification tests of the macro-realistic worldview. Here we have implemented the "bomb test" with a single atom trapped in a spin-dependent optical lattice to show explicitly a violation of the Leggett-Garg inequality-a quantitative criterion fulfilled by macro-realistic physical theories. To perform interaction-free measurements, we have implemented a novel measurement method that correlates spin and position of the atom. This method, which quantum mechanically entangles spin and position, finds general application for spin measurements, thereby avoiding the shortcomings inherent in the widely used push-out technique. Allowing decoherence to dominate the evolution of our system causes a transition from quantum to classical behavior in fulfillment of the Leggett-Garg inequality.
埃利祖尔和魏德曼提出了一种测量方案，该方案基于量子叠加原理，能让人在不与物体相互作用的情况下检测物体的存在——在一个极端场景中，比如检测一枚炸弹。吉拉尔迪指出，这种无相互作用测量方案可与宏观实在论世界观的证伪测试直接关联起来。在此，我们利用捕获在自旋相关光学晶格中的单个原子实现了“炸弹测试”，以明确展示对莱格特 - 加格不等式的违背——这是宏观实在论物理理论满足的一个定量标准。为了进行无相互作用测量，我们实现了一种将原子的自旋和位置相关联的新颖测量方法。这种方法通过量子力学使自旋和位置纠缠在一起，在自旋测量中有广泛应用，从而避免了广泛使用的推出技术所固有的缺点。让退相干主导我们系统的演化会导致从量子行为向经典行为的转变，这符合莱格特 - 加格不等式。
