A Chinese national has become one of the two recipients of the 2024 Oliver E. Buckley Condensed Matter Physics Prize, the top physics award in the United States, for achieving research breakthroughs in topological quantum materials.
Xue Qikun, 59, from Tsinghua University, was recognized “for groundbreaking theoretical and experimental studies on the collective electronic properties of materials that reflect topological aspects of their band structure.” (Another scientist, Ashvin Vishwanath, 50, from Harvard University, was simultaneously recognized for different work in the same field.)
Xue is the first Chinese national to receive the honor. He helped put Tsinghua University on the laureate list of the Prize, which was named after Oliver Ellsworth Buckley (1887-1959), an American electrical engineer known for his contributions to the field of submarine telephony.
Specialized in scanning tunneling microscopy and spectroscopy and surface materials, Xue would not have jumped into the field of topological quantum materials – which is more about electromagnetism – if Stanford University’s Zhang Shoucheng had not inspired him in 2008.
In a recent interview, Xue admitted that he was not a top student at school and had failed in public examinations and admission tests for doctoral programs. But he said he had worked harder after each setback. He said he definitely is a hard-charging researcher as he works from 7am to 11pm every day.
In contrast, the Shanghai-born Zhang was described as a child prodigy. His talent was such that he was admitted to Fudan University, a top Chinese university, at 15, two years earlier than his peers, and earned his bachelor’s degree at 18. He then studied in Germany. In 1983, he became a student of Chinese physicist Franklin Yang, a 1957 Nobel Prize laureate, at Stony Brook University in the New York state university system. He became a US national.
Yang had once said that Zhang would win the Nobel Prize sooner or later. But instead Zhang plunged to his death from a window of his San Francisco home on December 1, 2018, leaving behind Xue as a rising star in the academic world. Zhang ended his own life due to depression, his family has said, but other accounts express skepticism.
Coincidentally or not, Zhang died on a day when he was supposed to meet Huawei’s Chief Financial Officer Meng Wanzhou – but she was arrested between airline connections in Canada for alleged violation of American sanctions on Iran and spent three years under house arrest.
On November 27, 2018, just three days before his death, Zhang’s research team had announced a partnership with Huawei to develop semiconductors jointly.
Hall effect
Xue and his team became famous after an experiment in late 2012 in which they observed the “quantum anomalous Hall effect (QAHE)” when electric currents flow in topological materials. They published their findings in the journal Science in 2013.
In 2014, Franklin Yang praised Xue’s QAHE experiment as a “Nobel Prize-grade” achievement.
To understand what the QAHE is, one should know about the Hall effect, which was discovered in 1879 by American physicist Edwin Hall (1855-1938).
Hall used an electric field to change the path of an electric current. The discovery was used in the measurement of voltage and different electrical tools.
In 1980, German physicist Klaus von Klitzing discovered the quantum Hall effect, a quantized version of the Hall effect.
In 1988, British-born physicist Duncan Haldane suggested the concept of the QAHE (adding “anomalous” to the description), which is the quantum Hall effect created in the absence of an external magnetic field.
QAHE is now one of the two most popular research topics in condensed matter physics. The other is superconducting materials.
Overseas Chinese scientists
In fact, Zhang was among the 23 co-writers listed for Xue’s paper about the QAHE experiment in 2013.
They came together due to two programs that were aimed at luring overseas Chinese scientists back home.
Xue in 1994 earned his doctoral degrees from the Institute of Physics at the Chinese Academy of Sciences (CAS). He then worked as a research associate at the Institute for Materials Research of Tohoku University in Japan and as a visiting assistant professor at the Department of Physics of North Carolina State University in the US.
In 1999, he joined China’s “Hundred Talents Program” and returned to China to become a professor at his alma mater, the Institute of Physics at CAS. He joined Tsinghua in 2005.
In 2006, Zhang and his Stanford team co-wrote a paper about the “quantum spin Hall effect (QSHE),” which is expected to be used to make low-power-consumption electronics in the future.
In 2008, Zhang joined China’s newly enlarged welcome-home movement, that version called the “Thousand Talents Program,” intended to expand connections with Chinese scientists abroad. He did not leave Stanford or give up his US citizenship. Through the plan, he connected with Tsinghua and Xue’s laboratory.
In 2009, he helped Huawei to “resolve some difficult questions” in 5G technology, according to Chinese media accounts that offer little detail. He also suggested that Tsinghua perform tests on three topological insulators.
Zhang was one of the three winners of the Oliver Buckley Prize in 2012 “for the theoretical prediction and experimental observation of the QSHE, opening the field of topological insulators.”
Xue told the media that he and his team had no academic foundation in topological materials before they decided to start focusing on the QAHE in 2008. He said his team had tested more than 1,000 materials in four years and finally observed the QAHE.
“These achievements are a result of the continuous growth of China’s scientific and technological strength and the long-term and profound accumulation of basic scientific research since the country’s reform and opening up,” said Xue. “Therefore, honor belongs to every researcher in the team and more importantly to the country.”
Nobel Prize
Since the American Physical Society (APS) announced the 2024 winners of the Oliver E. Buckley Prize on October 24, Chinese state media have been promoting the achievement of Xue, who is the first Chinese national to win the award since its inception in 1953.
Over the past seven decades, most winners were Americans and British while a few were Japanese, Korean and Taiwanese scientists.
In fact, such Chinese scientists as Frank Fang (1988), Shen Zhixun (2011) and Wen Xiaogang (2017), had won the Prize, but they held American nationality.
Daniel Tsui Chee, born in Henan, was among the three recipients of the award in 1984 for the discovery of the fractional quantized Hall effect. He had studied in a Hong Kong secondary school before pursuing further studies in Augustana College in the US. He won the Nobel Prize in Physics in 1998.
Zhang’s death
Some observers said Xue may win the Nobel Prize one day. That remains to be seen. But Zhang definitely will not win the Nobel Prize, which cannot be awarded posthumously.
The 55-year-old scientist’s mysterious death came after his firm, Danhua Capital, was probed by the US in November 2018. It was accused of helping Chinese firms obtain US technologies. There has been no public update about the United States’ probe of Zhang’s firm since the scientist died.
His family blamed depression, saying Zhang had killed himself.
Some skeptical Chinese commentators say Zhang at the time was at the peak of his career and life, and they suggest US involvement in his death – but there are also reports that Zhang faced major financial problems involving his company.
On January 8, 2019, China granted Xue the State Natural Science Award (the first prize) to praise his achievement in the QAHE experiment, but without mentioning Zhang’s contributions.
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