Angular Momentum and Superposition of States

Yitian Ding, Miaomiao Xu

The Schwinger's representation of angular momentum(AM) relates two important fundamental models, that of AM and that of harmonic oscillator(HO). However, the representation offers only the relations of operators but not states. Here, by developing a graphic method to calculate the states, we show that the Schwinger's model is valid only with certain spin. With the relation of states, we also demonstrate how the superposition states in AM map to entangled states in HO. This study has promising applications in quantum computation, and may cast light on the relation between superposition and entanglement.

Harry A. Mavromatis

Fangwei Ye, Li Yong-Ping, (1)中国科学技术大学物理系,合肥 230026; (2)中国科学技术大学物理系,合肥 230026;中国科学技术大学结构分析开放实验室,合肥 230026

Laguerre-Gaussian(LG) mode carries a well-defined orbit angular momentum. We have designed a fork-like grating to measure the superposition of two LG modes. It is useful in the high-dimensional quantum communication.

Gennaro Auletta, Mauro Fortunato, Giorgio Parisi A

Yakir Aharonov, Leonard Susskind

Questions concerning superselection rules are considered. Two experiments are discussed. In the first, coherent superpositions of different angular-momentum states are constructed. In the second, coherent superpositions of states with different charge are constructed in complete analogy with the angular-momentum case. We suggest that, contrary to a widespread belief, interference may be possible between states with different charges.