We report the realization of a Hanbury Brown and Twiss (HBT)-like experiment with a gas of interacting bosons at low temperatures. The low-temperature regime is reached in a three-dimensional optical lattice and atom-atom correlations are extracted from the detection of individual metastable helium atoms after a long free fall. We observe, in the noncondensed fraction of the gas, a HBT bunching whose properties strongly deviate from the HBT signals expected for noninteracting bosons. In addition, we show that the measured correlations reflect the peculiar quantum statistics of atoms belonging to the quantum depletion and of the Bogoliubov phonons, i.e., of collective excitations of the many-body quantum state. Our results demonstrate that atom-atom correlations provide information about the quantum state of interacting particles, extending the interest of HBT-like experiments beyond the case of noninteracting particles.

中文翻译：

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相互作用的玻色气体中的Hanbury Brown和Twiss声子束和量子耗尽

我们报告了在低温下用相互作用的玻色子气体实现类似汉伯里·布朗和特维斯（HBT）的实验的实现。在三维光学晶格中达到低温状态，经过长时间的自由下落后，从检测单个亚稳态氦原子中提取了原子-原子相关性。我们在气体的非冷凝部分中观察到HBT束，其性质与非相互作用玻色子的HBT信号强烈偏离。此外，我们表明，测得的相关性反映了属于量子耗尽的原子和Bogoliubov声子的特殊量子统计，即多体量子态的集体激发。我们的结果表明，原子与原子的相关性提供了有关相互作用粒子的量子状态的信息，