Magneto-optical trap can cool and capture atomic vapor, which has a wide application prospect in modern atomic physics. The cold atom ensemble obtained by magneto-optical trap is the necessary basis for realizing long-time quantum bits and applications such as quantum precision measurement, quantum simulation and calculation.
However, the traditional magneto-optical trap system is partially limited in further extensible applications, such as multi-channel free space beam alignment, huge anti-Helmholtz coil, strict coincidence of magnetic field and light field center, etc. Therefore, how to realize miniaturization or even chip-based magneto-optical trap system has aroused widespread interest in the world. Among them, the magneto-optical trap based on grating chip greatly simplifies the incident system of six beams of space light in the traditional magneto-optical trap, which is not only small in size, light in weight, rich in optical windows and high in expansibility, but also has great potential in mobile quantum precision measurement system and integrated quantum computing system.
But for another important part of magneto-optical trap-magnetic field coil, it can only be realized by three-dimensional coil before. If the size of the magnetic field coil is large, thicker wires and stronger current are needed to realize the required magnetic field gradient, resulting in high power consumption and serious heating. If the size of the coil is reduced, the coil may seriously obstruct the optical path and reduce the available optical window size.
Therefore, Zou Changling, a team of academicians from Guo Guangcan, cooperated with Professor Lu Zhengtian to propose a brand-new planar magnetic field coil configuration, which only needs a 3cm 3cm chip to generate the quadrupole magnetic field required by magneto-optical traps. Based on the micro-nano machining center of China University of Science and Technology, they independently designed and manufactured the magnetic field chip and grating chip which matched each other, and on this basis, they successfully captured more than 106 low-temperature 87Rb atoms, which proved the practicability of this novel configuration. They combined the self-designed magnetic field chip and grating chip to realize the cold atom magneto-optical trap system based on double chips. The related results were recently published online in the journal Physical Review Application.
The two chips designed by the aforementioned team are small in size, light in weight and low in power consumption, which frees up more optical windows. In addition, it is very convenient to use. The two chips can be stacked together, and only need to fix transparent glue outside the vacuum glass window, and the incidence of a single laser beam can capture cold atoms. Among them, the 6.4W (W) magnetic field chip can be driven, and it is expected to use portable storage battery to supply power, which will promote the further integration of small magneto-optical trap system.
The team further explored the relationship between the performance of magneto-optical trap and various parameters under the new configuration. The researchers observed in the experiment that with the increase of magnetic field current, the detuning of local optimal light field will increase approximately linearly. Based on the energy level configuration of atoms, the research team suggested that this may be caused by the decrease of magnetic field size. Experiments confirmed the new characteristics of this magneto-optical trap control, which was easily overlooked in the traditional three-dimensional large coil configuration. This study not only observed this important physical phenomenon in the experiment, but also got a new understanding of the performance of magneto-optical trap.
The reviewer commented: "I think this work will attract the attention of atoms, molecules and optics (AMO). In these fields, grating magneto-optical trap (MOT) and micromat technology are becoming people's interests, and this work has a real impact and is closely related to practical applications."
Chen Liang, a graduate student in the Key Laboratory of Quantum Information of China Academy of Sciences, is the first author of the paper, and Professor Zou Changling is the author of the paper. The above research work is supported by the national key R&D projects, the National Natural Science Foundation, the special funds for basic scientific research operating expenses of central universities and the open project of the State Key Laboratory of Market Supervision (time-frequency and gravity measurement benchmark). Related achievements have been patented and authorized.
Proofreading: Ding Xiao