Deterministic spin-wave interferometer based on Rydberg blockade
  The spin-wave (SW) NOON state is an $N$-particle Fock state with two atomic spin-wave modes maximally entangled. Attributed to the property that the phase is sensitive to collective atomic motion, the SW NOON state can be utilized as a novel atomic interferometer and has promising application in quantum enhanced measurement. In this paper we propose an efficient protocol to deterministically produce the atomic SW NOON state by employing Rydberg blockade. Possible errors in practical manipulations are analyzed. A feasible experimental scheme is suggested. Our scheme is far more efficient than the recent experimentally demonstrated one, which only creates a heralded second-order SW NOON state. 
Ran Wei, Bo Zhao, Youjin Deng, Yu-Ao Chen, Jian-Wei Pan
quant-ph cond-mat.quant-gas physics.atom-ph