论文标题
玻色子混合物中量子液滴的声子稳定性和声速
Phonon Stability and Sound Velocity of Quantum Droplets in a Boson Mixture
论文作者
论文摘要
量子液滴已在二元玻色子混合物和偶极bose气体的实验中实现。在这些系统中，Bose-Einstein凝结的平均场能具有吸引力，而排斥的Lee-huang-yang能量对于稳定性至关重要。 Bogoliubov理论错误地预测，声子模式在长波长极限下动态不稳定。在这项工作中，我们超越了Bogoliubov理论，以研究如何在二元玻色子混合物的量子液滴中稳定声子模式。与贝利亚夫（Beliaev）对单组分玻色气体的方法类似，我们计算了对玻色子传播器的自我能源的高阶贡献。我们发现，自旋和声子激发之间的相互作用是声子稳定性的关键。我们获得声速，可以通过测量实验中液滴的超流体临界速度来测试。还讨论了该量子液滴的Beliaev阻尼。
Quantum droplets have been realized in experiments on binary boson mixtures and dipolar Bose gases. In these systems, the mean-field energy of the Bose-Einstein condensation is attractive, and the repulsive Lee-Huang-Yang energy is crucial for stability. The Bogoliubov theory incorrectly predicts that the phonon mode is dynamically unstable in the long-wavelength limit. In this work, we go beyond the Bogoliubov theory to study how the phonon mode is stabilized in the quantum droplet of a binary boson mixture. Similar to Beliaev's approach to a single-component Bose gas, we compute higher-order contributions to the self-energy of the boson propagator. We find that the interaction between spin and phonon excitations is the key for the phonon stability. We obtain the sound velocity which can be tested by measuring the superfluid critical velocity of the droplet in experiments. Beliaev damping of this quantum droplet is also discussed.
