Department of Physics and Astronomy, Center for Theoretical Physics, Seoul National University, 151-747 Seoul, Korea.
Phys Rev Lett. 2015 Dec 31;115(26):260404. doi: 10.1103/PhysRevLett.115.260404. Epub 2015 Dec 28.
We consider ultracold quantum gases of scalar bosons residing in a coupling strength-density regime in which they constitute a twofold fragmented condensate trapped in a single well. It is shown that the corresponding quantum states are, in the appropriate Fock space basis, identical to the photon cat states familiar in quantum optics, which correspond to superpositions of coherent states of the light field with a phase difference of π. In marked distinction to photon cat states, however, the very existence of matter-wave cat states crucially depends on the many-body correlations of the constituent bosons. We consequently establish that the quadratures of the effective "photons," expressing the highly nonclassical nature of the macroscopic matter-wave superposition state, can be experimentally accessed by measuring the density-density correlations of the interacting quantum gas.
我们研究了处于耦合强度-密度范围内的标量玻色子的超冷量子气体，这些玻色子在单个势阱中形成了双重分裂的凝聚态。结果表明，在适当的福克（Fock）空间基下，相应的量子态与量子光学中熟知的光子猫态完全相同，这些态对应于光场的相干态的叠加，相位差为π。然而，与光子猫态明显不同的是，物质波猫态的存在关键取决于组成玻色子的多体相关性。因此，我们证明了有效“光子”的正交分量可以通过测量相互作用的量子气体的密度-密度相关来实验探测，这些正交分量反映了宏观物质波叠加态的高度非经典性质。
