Yitang Zhang

Yitang Zhang (; born February 5, 1955) is a Chinese-American mathematician primarily working in the field of number theory. He is a professor of mathematics at Sun Yat-sen University.

While working in obscurity as a lecturer at the University of New Hampshire, Zhang submitted a groundbreaking paper on the Twin Prime Conjecture to the Annals of Mathematics in 2013, establishing the first finite bound on the least gap between consecutive primes that is attained infinitely often. For his research, he was awarded the Ostrowski Prize in 2013, then the Cole Prize, Rolf Schock Prize, and a MacArthur Fellowship, all in 2014.

Zhang became a professor of mathematics at the University of California, Santa Barbara, in fall 2015. He retired from the university in 2025 and returned to China as a professor at Sun Yat-sen University.

Early life and education Zhang was born in Shanghai, China. His ancestral home is in Pinghu, Zhejiang. He lived in Shanghai with his grandmother until he attended college. At around 9 years old, he found a proof of the Pythagorean theorem. He first learned about Fermat's Last Theorem and Goldbach's conjecture when he was 10 years old.

With recommendations from Ding Shisun, the president of Peking University, and Deng Donggao, the chair of the math department at Peking University, Zhang won a full scholarship to pursue doctoral studies at Purdue University, beginning in January 1985. He earned his Ph.D. in mathematics in December 1991.

Career Zhang's PhD work was on the two-dimensional Jacobian conjecture. After graduation, Zhang had trouble finding an academic position. In a 2013 interview with Nautilus magazine, Zhang said he did not get a job after graduation. "During that period it was difficult to find a job in academics. That was a job market problem. Also, my advisor [Tzuong-Tsieng Moh] did not write me letters of recommendation." Zhang made this claim again in George Csicsery's documentary film "Counting from Infinity: Yitang Zhang and the Twin Prime Conjecture" while discussing his difficulties at Purdue and in the years that followed.

After some years, Zhang managed to find a position as a lecturer at the University of New Hampshire, where he was hired by Kenneth Appel in 1999. Prior to getting back to academia, he worked for several years as an accountant and a delivery worker for a New York City restaurant. He also worked in a motel in Kentucky and in a Subway sandwich shop. until around January 2014, when UNH appointed him to a full professorship as a result of his breakthrough on prime numbers. He took a full-time position at Sun Yat-sen University in Guangzhou, China on June 27, 2025. As of September 2025, Zhang works at the university's main campus in Guangzhou, but plans to primarily work at the university's Hong Kong Institute of Advanced Study in Hong Kong after its construction is completed.

Research

On April 17, 2013, Zhang announced a proof that there are infinitely many pairs of prime numbers that differ by less than 70 million. This result implies the existence of an infinitely repeatable prime 2-tuple, his first publication since his last paper in 2001. The proof was refereed by leading experts in analytic number theory. Researchers built off Zhang's result, for example in the Polymath Project.

If P(N) stands for the proposition that there is an infinitude of pairs of prime numbers (not necessarily consecutive primes) that differ by exactly N, then Zhang's result is equivalent to the statement that there exists at least one even integer k < 70,000,000 such that P(k) is true. The classical form of the twin prime conjecture is P(2); and in fact it has been conjectured that P(k) holds for all even integers k. While these stronger conjectures remain unproven, a result due to James Maynard in November 2013, employing a different technique, showed that P(k) holds for some k ≤ 600. Subsequently, in April 2014, the Polymath project 8 lowered the bound to k ≤ 246. If the Elliott–Halberstam conjecture and its generalization, respectively, hold, then k ≤ 12 and k ≤ 6 follow using current methods. the 2013 Ostrowski Prize, the 2014 Frank Nelson Cole Prize in Number Theory, and the 2014 Rolf Schock Prize in Mathematics.

He is a recipient of the 2014 MacArthur award, and was elected as an Academia Sinica Fellow during the same year.

Political views In 1989 Zhang joined a group interested in Chinese democracy . In a 2013 interview, he affirmed that his political views on the subject had not changed since. In 2025, Zhang cited the "political climate" of the United States as a reason for his return to China.

Publications