Recently, the team of Academician Guo Guangcan of the University of Science and Technology of China collaborated with Professor Lu Zhengtian to make new progress in chip-based cold atom systems, and for the first time realized a dual-chip cold atom magneto-optical trap system. This achievement will help realize quantum precision measurement, quantum simulation and computing-related applications, such as quantum gravimeters, quantum memories, etc.
Magneto-optical traps can cool and capture atomic vapor and have broad application prospects in the field of modern atomic physics. The cold atom ensemble obtained through the magneto-optical trap is the necessary foundation for realizing long coherence time qubits and realizing applications such as quantum precision measurement, quantum simulation and calculation based on this.
However, traditional magneto-optical trap systems are subject to some limitations in further scalable applications, such as multi-channel free-space beam alignment, huge anti-Helmholtz coils, and the strict coincidence of magnetic field and light field centers. Waiting for challenges. Therefore, how to realize miniaturization and even chip-based magneto-optical trap systems has attracted widespread international interest. Among them, the magneto-optical trap based on the grating chip greatly simplifies the incident system of six spatial light beams in the traditional magneto-optical trap. It is not only small in size, light in weight, rich in optical windows, and highly scalable, but also in the mobile quantum precision measurement system. , there is huge potential in integrated quantum computing systems.
But for another important component of the magneto-optical trap, the magnetic field coil, it could only be realized with three-dimensional coils before. If the size of the magnetic field coil is larger, thicker wires and stronger current are needed to achieve the required magnetic field gradient, which ultimately results in high power consumption and serious heating. If the size of the coil is reduced, the coil may significantly obstruct the optical path, reducing the size of the optical window available for use.
To this end, Academician Guo Guangcan’s team and Zou Changling’s research group collaborated with Professor Lu Zhengtian to propose a new planar magnetic field coil configuration that only requires a 3cm 3cm chip to generate the required magneto-optical traps. quadrupole magnetic field. Based on the Micro-Nano Processing Center of the University of Science and Technology of China, they independently designed and processed matching magnetic field chips and grating chips, and based on this, they successfully captured more than 106 low-temperature 87Rb atoms, proving the practicability of this novel configuration. They combined an independently designed magnetic field chip with a grating chip to realize a dual-chip cold atom magneto-optical trap system. Relevant results were recently published online in the journal "Physical Review Applied".
The two chips independently designed by the aforementioned team are small in size, light in weight and low in power consumption, freeing up more optical windows. In addition, it is also very convenient to use. Two chips can be stacked together, and only transparent glue is required to be fixed outside the vacuum glass window. Cold atoms can be captured by a single laser beam. Among them, the magnetic field chip can be driven with 6.4W (Watt) and is expected to be powered by portable batteries, promoting the further integration of small magneto-optical trap systems.
The team also further explored the relationship between the performance of the magneto-optical trap and various parameters in the new configuration. In the experiment, the researchers observed that as the magnetic field current increases, the local optimal optical field detuning also increases approximately linearly. Starting from the energy level configuration of atoms, the team proposed that this may be due to the reduction in the size of the magnetic field, and experimentally confirmed this new feature of magneto-optical trap control, which is easily overlooked in the traditional three-dimensional large coil configuration. This research work not only experimentally observed this important physical phenomenon, but also provided a new understanding of the performance of magneto-optical traps.
The reviewer commented: "I think this work will attract attention in the atomic, molecular and optics (AMO) field, where grating magneto-optical traps (MOTs) and micro-MOTs Technology is becoming people’s interest, and this work has real impact and is closely related to practical applications.”
Chen Liang, a graduate student at the Key Laboratory of Quantum Information of the Chinese Academy of Sciences, is the first author of the paper and Professor Zou Changling. He is the corresponding author of the paper. The aforementioned research work was funded by the National Key Research and Development Project, the National Natural Science Foundation, the Fundamental Research Funds for the Central Universities, and the National Market Supervision Key Laboratory (Time Frequency and Gravity Measurement Benchmark) Open Project. Relevant results have been patented and authorized.
Proofreading: Ding Xiao