Liang Danfu, Zhu Yifu, Li Hebin
Department of Physics, Florida International University, Miami, Florida 33199, USA.
Phys Rev Lett. 2022 Mar 11;128(10):103601. doi: 10.1103/PhysRevLett.128.103601.
Collective resonance of interacting particles has important implications in many-body quantum systems and their applications. Strong interactions can lead to a blockade that prohibits the excitation of a collective resonance of two or more nearby atoms. However, a collective resonance can be excited with the presence of weak interaction and has been observed for atoms in the first excited state (P state). Here, we report the observation of collective resonance of rubidium atoms in a higher excited state (D state) in addition to the first excited state. The collective resonance is excited by a double-quantum four-pulse excitation sequence. The resulting double-quantum two-dimensional (2D) spectrum displays well-isolated peaks that can be attributed to collective resonances of atoms in P and D states. The experimental one-quantum and double-quantum 2D spectra can be reproduced by a simulation based on the perturbative solutions to the optical Bloch equations, confirming collective resonances as the origin of the measured spectra. The experimental technique provides a new approach for preparing and probing collective resonances of atoms in highly excited states.
相互作用粒子的集体共振在多体量子系统及其应用中具有重要意义。强相互作用会导致一种阻塞，阻止两个或更多相邻原子的集体共振激发。然而，在弱相互作用存在的情况下可以激发集体共振，并且已经在处于第一激发态（P态）的原子中观察到。在此，我们报告除了第一激发态之外，还观察到处于更高激发态（D态）的铷原子的集体共振。通过双量子四脉冲激发序列激发集体共振。所得的双量子二维（2D）光谱显示出可以归因于处于P态和D态的原子的集体共振的良好分离的峰。基于光学布洛赫方程的微扰解进行的模拟可以重现实验的单量子和双量子2D光谱，证实集体共振是所测光谱的起源。该实验技术为制备和探测处于高激发态的原子的集体共振提供了一种新方法。
