Lee Jae-Seung, Khitrin A K
Department of Chemistry, Kent State University, Kent, Ohio 44242-0001, USA.
Phys Rev Lett. 2005 Apr 22;94(15):150504. doi: 10.1103/PhysRevLett.94.150504.
It is experimentally demonstrated that an arbitrary quantum state of a single spin 1/2, a| upward arrow+b| downward arrow, can be converted into a superposition of the two ferromagnetic states of a spin cluster: a| upward arrow upward arrow... upward arrow upward arrow+b| downward arrow downward arrow... downward arrow downward arrow. The physical system is a cluster of seven dipolar-coupled nuclear spins of single-labeled 13C-benzene molecules in a liquid-crystalline matrix. In this complex system, the pseudopure ground state and the required controlled unitary transformations have been implemented. The experimental scheme can be considered as an explicit model of quantum measurement.
实验证明，单自旋1/2的任意量子态，即a|向上箭头⟩ + b|向下箭头⟩，可以转换为自旋簇的两个铁磁态的叠加态：a|向上箭头向上箭头……向上箭头向上箭头⟩ + b|向下箭头向下箭头……向下箭头向下箭头⟩。物理系统是处于液晶基质中的单标记13C - 苯分子的七个偶极耦合核自旋的簇。在这个复杂系统中，已经实现了伪纯基态和所需的受控酉变换。该实验方案可被视为量子测量的一个明确模型。
