双语阅读Physicists discover a hidden “curveball” in quantum light

Now, an international team working at the Paul Scherrer Institute PSI has observed a related effect at the atomic scale. For the first time, researchers have experimentally demonstrated the optical Magnus effect by focusing laser light on a single ion and measuring how the light interacts with it.
现在，一个在保罗·谢勒研究所工作的国际团队在原子尺度上观察到了类似的现象。研究人员首次通过将激光聚焦在单个离子上，并测量激光与该离子的相互作用方式，从而实验性地验证了光学马格努斯效应。

Instead of causing an atom to follow a curved path, the effect shifts the location where the laser interacts most strongly with the ion. That interaction point moves slightly sideways, a finding that could matter for quantum computers that use laser light to control qubits with extreme precision. The results were published in Physical Review Letters.
这种效应并不会使原子沿曲线路径运动，而是会改变激光与离子发生最强烈相互作用的部位。该相互作用点会稍微向侧面移动。这一发现对于那些利用激光来精确控制量子比特的量子计算机来说非常重要。该研究结果发表在《物理评论快报》上。

A Laser’s Strongest Interaction Is Slightly Off Center
激光最强的相互作用力其实略偏中心位置。

At first glance, it seems reasonable to expect that an ion would interact most strongly with a laser exactly at the beam’s brightest point. But when laser light is focused very tightly, the structure of its electromagnetic field becomes more complicated.
乍看之下，人们可能会认为，离子与激光的相互作用最强烈的地方，应该就是激光束最明亮的那一点。但实际上，当激光被高度聚焦时，其电磁场的结构会变得更为复杂。

Because of that altered field structure, the strongest interaction does not occur exactly at the center of the beam. Instead, it appears slightly to one side. This small sideways displacement is the optical equivalent of the Magnus effect that makes a spinning table tennis ball curve through the air.
由于这种场结构的改变，最强的相互作用并不发生在光束的正中心。相反，它略微偏移至一侧。这种微小的偏移现象，在光学上相当于“马格努斯效应”——也就是让旋转中的乒乓球在空气中呈曲线飞行的现象。

That tiny shift could become important in quantum computing. Lasers are often used to change the states of qubits with very high precision. If the optical Magnus effect is ignored, it could interfere with that control and contribute to errors.
这一微小的变化在量子计算中可能会起到重要作用。激光通常被用来以极高的精度来改变量子比特的状态。如果忽略光学马格努斯效应，就会干扰这种控制过程，从而导致错误。

The same effect may also be useful. “The forces it generates could be used to couple qubits to one another, enabling more complex computations,” explains first author Philip Leindecker from the PSI Center for Photon Science and the Department of Physics at ETH Zurich.
同样的效果也可能具有实用价值。“它所产生的力可以被用来将量子比特相互连接起来，从而实现更复杂的计算，”该研究的第一作者、来自苏黎世联邦理工学院光子科学中心及物理系的菲利普·莱因德克解释道。

Using a Single Ion to Map Laser Light
利用单个离子来探测激光光束的分布情况

To detect the effect, the researchers used a single calcium ion as an extremely sensitive probe. The electrically charged atom was held nearly motionless in an ion trap, which uses electromagnetic fields to keep the ion fixed in place.
为了检测这种效应，研究人员使用了一个钙离子作为极其灵敏的探测工具。这个带电原子被牢牢地束缚在离子阱中，而离子阱则利用电磁场来确保该原子不会移动。

Trapped ions are also widely used in quantum computing. They can function as qubits, with their quantum states manipulated using carefully controlled laser pulses.
被囚禁的离子在量子计算中也得到了广泛应用。它们可以被当作量子比特来使用，其量子状态可以通过精确控制的激光脉冲来操控。

In the experiment, the team moved the calcium ion through different parts of a tightly focused laser beam and measured how strongly it interacted with the light at each position.
在实验中，研究团队让钙离子穿过聚焦良好的激光束的不同区域，并测量了钙离子在各个位置上与光的相互作用强度。

“Our ion acts like a tiny sensor that we can use to feel out the structure of the laser light,” Leindecker explains. “This makes it possible to measure a shift of just a few hundred nanometers.”
“我们的离子就像一个微型传感器，我们可以利用它来了解激光的光谱结构，”莱因德克解释道。“这样一来，即便只有几百纳米的微小位移，我们也能够测量出来。”

The measurements uncovered another surprising feature. The size of the sideways shift depends only on the wavelength of the light and not on how tightly the laser beam is focused.
这些测量结果还揭示了另一个令人惊讶的现象：光束的横向偏移大小仅取决于光的波长，而与激光束的聚焦程度无关。

Researchers at the University of Amsterdam had predicted the optical Magnus effect theoretically several years ago. By using a trapped calcium ion as a microscopic probe, the team has now observed the effect experimentally for the first time and measured its behavior in greater detail.
几年前，阿姆斯特丹大学的研究人员从理论上预测了这种光学马格努斯效应。现在，该团队利用被捕获的钙离子作为微观探针，首次在实验中观察到了这一现象，并对其行为进行了更详细的测量。