USTC realizes chip-integrated cold-atom magneto-optical trap system for the first time
The team of Academician Guo Guangcan of USTC and Professor Lu Zhengtian have made new progress in the chip-based cold atom system. The team of Zou Changling's research group combined an independently designed magnetic field chip with a grating chip to realize a dual-chip-based cold atom magneto-optical trap system. The related results were published online on March 10 in the international academic journal "Physical Review Applied" with the title "Planar-integrated magneto-optical trap".
As one of the basic means of cooling and trapping atomic vapors, magneto-optical traps are widely used in the field of modern atomic physics. The cold atom ensemble obtained by the magneto-optical trap is a necessary basis for the realization of long coherence time qubits and applications based on it, such as quantum precision measurement, quantum simulation, and quantum computing. However, conventional MOT systems are limited in further scalable applications, such as the challenges of multiplex free-space beam alignment, bulky anti-Helmholtz coils, and strict coincidence of magnetic and optical field centers. Therefore, how to realize the miniaturized and even chipped magneto-optical trap system has attracted extensive interest from international researchers. Among them, the magneto-optical trap based on the grating chip greatly simplifies the incident system of the six beams of space light in the traditional magneto-optical trap, with small size, light weight, rich optical windows, and high scalability. It is used in mobile quantum precision measurement systems, integrated There is great potential in quantum computing systems.
However, for another important component of the magneto-optical trap, the magnetic field coil, we still can only use three-dimensional coil pairs to achieve it. If the size of the magnetic field coil is larger, thicker wires and stronger currents are required to achieve the learned magnetic field gradient, resulting in high power consumption and serious heat generation. If the size of the coil is reduced, the coil may severely obstruct the optical path, reducing the size of the available optical window. In order to solve this problem, Zou Changling's research group, in cooperation with Professor Lu Zhengtian, proposed a new planar magnetic field coil configuration, which can generate the quadrupole magnetic field required by the magneto-optical trap with only a 3cm×3cm chip. Based on the Micro-Nano Machining Center of the University of Science and Technology of China, they independently designed and processed a magnetic field chip and a grating chip that matched each other, and based on this, they successfully captured more than 106 low-temperature 87Rb atoms, proving the practicability of this novel configuration.
These two chips are small in size, light in weight, and low in power consumption, freeing up more optical windows. They are also very convenient to use. Two chips can be stacked together, and only need to be fixed outside the glass window of the vacuum with transparent glue, and the cold atoms can be captured by a single laser beam. Among them, the magnetic field chip can be driven with only 6.4W, and it is expected to be powered by a portable battery, which promotes the further integration of small magneto-optical trap systems.
In addition, this work further explores the relationship between the performance of the magneto-optical trap and various parameters under the new configuration. It is observed in experiments that with the increase of the magnetic field current, the locally optimal optical field detuning also increases approximately linearly. Starting from the energy level configuration of atoms, the research group proposed that this may be caused by the reduction in the size of the magnetic field, and experimentally verified this new feature of magneto-optical trap regulation, which is just easy under the traditional three-dimensional large coil configuration. be ignored. This work experimentally observes this important physical phenomenon and provides a new understanding of the behavior of magneto-optical traps.
The reviewers spoke highly of the work: "I think this work will attract the attention of the AMO field, where grating MOT and micro-MOT technologies are becoming of interest, and this work has real impact, and has a strong connection to practical applications. (I think the work will be of interest to the AMO community, where grating MOTs and miniature MOT technologies are becoming of interest, and moreover, it will have real implications and has strong ties to concrete applications .)" "Enough 'new insight' for the work".
(a) Conceptual schematic of a conventional quadrupole coil. (b) Conceptual schematic of the coil chip. (c) Photograph of the chip coil. (d) Chip coil stable voltage and power characterization. (e), (f) Characterization of chip coil axis and radial magnetic field distribution.
Schematic diagram of the dual-chip magneto-optical trap (left) and CCD imaging photo of the trapped cold atoms (right)
Chen Liang, a graduate student of the Key Laboratory of Quantum Information, Chinese Academy of Sciences, is the first author of the paper, and Professor Zou Changling is the corresponding author of the paper. This work was funded by the National Key Research and Development Project, the National Natural Science Foundation of China, the Special Fund for the Fundamental Research Funds of the Central Universities and the Open Project of the National Key Laboratory of Market Supervision (Time Frequency and Gravimetric Benchmark). The related achievements of this work have been applied for and authorized, the patent number is ZL 2020 1 0707864.2.
Link:
https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.17.034031
