Ultracold temperatures in dilute quantum gases opened the way to an exquisite control of matter at the quantum level. Here we focus on the control of ultracold atomic collisions using a laser to engineer their interactions at large interatomic distances. We show that the entrance channel of two colliding ultracold atoms can be coupled to a repulsive collisional channel by the laser light so that the overall interaction between the two atoms becomes repulsive: this prevents them to come close together and to undergo inelastic processes, thus protecting the atomic gases from unwanted losses. We illustrate such an optical shielding (OS) mechanism with ³⁹K and ¹³³Cs atoms colliding at ultracold temperature (<1 μK). The process is described in the framework of the dressed-state picture and we then solve the resulting stationary coupled Schrödinger equations. The role of spontaneous emission and photoinduced inelastic scattering is also investigated as possible limitations of the shielding efficiency. We predict an almost complete suppression of inelastic collisions over a broad range of Rabi frequencies and detunings from the ³⁹K D2 line of the OS laser, both within the [0, 200 MHz] interval. We found that the polarization of the shielding laser has a minor influence on this efficiency. This proposal could easily be formulated for other bialkali-metal pairs as their long-range interaction are all very similar to each other.

中文翻译：

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设计超冷原子与光之间的远程相互作用

稀量子气体中的超冷温度为在量子水平上精确控制物质开辟了道路。在这里，我们专注于使用激光控制超冷原子碰撞，以设计它们在大原子间距离的相互作用。我们表明，两个碰撞的超冷原子的入口通道可以通过激光耦合到排斥碰撞通道，从而使两个原子之间的整体相互作用变得排斥：这可以防止它们靠近并经历非弹性过程，从而保护不必要损失的原子气体。^我们用39 K 和¹³³来说明这种光屏蔽 (OS) 机制Cs 原子在超冷温度 (<1 μK) 下碰撞。该过程在穿着状态图的框架中进行了描述，然后我们求解了由此产生的稳态耦合薛定谔方程。自发辐射和光致非弹性散射的作用也作为屏蔽效率的可能限制进行了研究。我们预测在广泛的 Rabi 频率范围内几乎完全抑制非弹性碰撞和OS 激光器的³⁹ K D2 线的失谐，都在 [0, 200 MHz] 间隔内。我们发现屏蔽激光器的偏振对该效率的影响很小。该提议可以很容易地用于其他双碱金属对，因为它们的长程相互作用彼此非常相似。