How about being a postdoctoral immigrant abroad?

According to the relevant regulations of the U.S. government, the above-mentioned personnel who come to the United States with a J- 1 visa generally stay in the United States for no more than three years, and the visa type may not be changed during this period. After expiration, you must return to your country of origin. If the above-mentioned personnel want to apply for re-entry into the United States, they must live in their country of origin for more than two years. Applying for a J- 1 visa to come to the United States means that the visa applicant should return to the original country after the expiration of his stay in the United States. This is an important difference between the J- 1 visa and other visas.

American J- 1 visa is a non-immigrant visa, which is issued to all kinds of foreigners who come to the United States to participate in the exchange visit program approved by the State Council. The purpose is to provide educational and cultural exchange opportunities for the United States and other countries, so as to enhance mutual understanding, promote international cooperation and develop friendly relations between countries.