Deng Jiaxian

Family and Education

Deng Jiaxian was born on 25 June 1924 in Huaining, Anhui. His father, Deng Yizhe, was an aesthetician and art theorist who taught at Tsinghua University. As a boy Deng attended Chongde Middle School in Beiping, where Yang Chen-Ning was also a pupil; the two families came from the same region and were long-standing friends. In 1940 Deng left Japanese-occupied Beiping and made his way to Kunming, entering the physics department of National Southwest Associated University in 1941 and graduating in 1945. After the war he returned to Beiping as a teaching assistant in the physics department of Peking University.

In 1948 Deng went to study at Purdue University in the United States. According to a 2024 commemorative article in Science and Technology Daily, he consulted Yang, who was already in the United States, before choosing Purdue, and Yang helped him financially before his scholarship came through. Deng received his PhD in physics from Purdue in August 1950 and boarded a ship for China on 29 August, nine days after receiving his degree.

Eight Years at the Institute of Modern Physics (1950–1958)

After his return Deng worked on nuclear theory at the Institute of Modern Physics of the Chinese Academy of Sciences (later reorganised as the Institute of Atomic Energy), as an associate research fellow. He joined the Jiusan Society in 1951 and in 1953 married Xu Luxi, daughter of Xu Deheng, a student leader of the May Fourth Movement and founder of the Jiusan Society; the couple had a daughter and a son. Deng joined the Chinese Communist Party in 1956.

Theoretical Design of the Atomic and Hydrogen Bombs

In August 1958, Qian Sanqiang, Vice Minister of the Second Ministry of Machine Building, recruited Deng to the nuclear weapons research organisation then being established (the Ministry's Ninth Institute, later the Ninth Academy and today the China Academy of Engineering Physics), where he became Director of the Theoretical Department, responsible for the atomic bomb's theoretical design. The work was strictly secret; according to official commemorative materials, Deng told his wife Xu Luxi only that he was being transferred, and could not say where or to do what. For the next 28 years his name disappeared from public view. In a 2004 interview with Tsinghua students, Xu said the family had lived in the same Beijing residence since 1960, although Deng spent long periods away from his family.

The Theoretical Department began with little computing equipment. According to official commemorative materials, the design team Deng led carried out extensive simulations of the atomic bomb's physical processes using hand-cranked calculators and abacuses, working on detonation physics, hydrodynamics, equations of state and neutron transport. According to recollections by Zhou Guangzhao and others, Soviet specialists had described orally a teaching model of an atomic bomb together with a key figure; when the Institute, under Peng Huanwu, checked it, its results differed sharply from the Soviet figure. The calculation was repeated nine times on hand-cranked calculators — the Institute's well-known 'nine calculations' — until Zhou showed on physical grounds that the model's initial configuration could not produce the Soviet figure. Deng took part in the discussions of this period. In March 1963 the Theoretical Department completed the theoretical design for China's first atomic bomb; in September that year Deng and his colleagues took on the theoretical design of the hydrogen bomb.

China's first atomic bomb was detonated at Lop Nur on 16 October 1964, and its first hydrogen bomb was successfully tested in an airburst on 17 June 1967. Official materials state that Deng 'organised and led research into the hydrogen bomb's design principle and the selection of its technical approach' and took part in developing and testing the first hydrogen bomb; official accounts generally credit the key breakthrough on the hydrogen bomb principle to a group led by Yu Min. A 2024 exhibition organised by Tsinghua University with the archives of the China Academy of Engineering Physics states that Deng also made important contributions to China's first airdropped nuclear bomb test, its first nuclear missile flight test and its first submarine-launched nuclear missile test. According to a 2021 Xinhua report, China conducted 32 nuclear tests between 1964 and 1986, 15 of which Deng took part in or directed in person; 2022 materials from the China National Nuclear Corporation instead say he was present at 32 of China's 45 nuclear tests and personally directed 15.

Leading the Ninth Academy and the 1979 Accident

Deng became Deputy Director of the Ninth Academy in 1972. Sources differ on when he became Director: a 2013 Tsinghua University chronology gives 1980, while a 2024 exhibition organised with the archives of the China Academy of Engineering Physics gives 1979. He was elected a member of the Chinese Academy of Sciences in 1980; in 1982 he became Deputy Director of the Science and Technology Committee of the Ministry of Nuclear Industry, was elected to the 12th Central Committee of the CCP, and received a First-Class National Natural Science Award. At the end of 1984 he directed the last nuclear test he would oversee.

According to the Tsinghua chronology, in 1979 Deng went in person to deal with an accident during a nuclear test and suffered severe radiation exposure (other official materials say 'the late 1970s'). According to a 2024 commemorative article in People's Weekly, an airdropped nuclear bomb fell straight to the ground when its parachute failed to open, and no nuclear explosion occurred; more than a hundred chemical-defence troops searched without finding it. Deng insisted on going himself; on arrival he would not let Vice Minister Zhao Jingpu or the driver accompany him, entered the accident area alone, found a fragment, identified it as plutonium metal, and concluded from this that no nuclear explosion had occurred. Xu Luxi recalled him saying: 'Nobody else go — let me go in. You wouldn't find it anyway, and you'd be contaminated for nothing. I made it; I know it.' She added that the worst thing was that, when he found the fragments, he picked them up in his hands. According to the same article, tests in Beijing a few days later found strong radioactivity in his urine, powder-like chromosomes in his white blood cells and damage to his liver.

Illness and Legacy

Deng was admitted to hospital at the end of July 1985 and operated on on 10 August; he was diagnosed with rectal cancer that had already spread to the lymph nodes and surrounding tissue. From his hospital bed, he and Yu Min jointly signed a proposal to the Party Centre on 2 April 1986 setting out goals and measures for the future development of China's nuclear weapons. Official commemorative materials describe the proposal as anticipating that the nuclear powers would push for a comprehensive test ban, and that China needed to complete essential tests before then. On 29 July 1996, the tenth anniversary of Deng's death, China conducted its last nuclear test and announced a moratorium on testing the same day.

In June 1986 the Central Military Commission decided to declassify Deng's work. On 24 June the PLA Daily reported on him for the first time on its front page, under a headline calling him the 'founding figure of the two bombs'; People's Daily, Outlook Weekly and other outlets followed. On 17 July, at the PLA General Hospital, he was awarded the title of National Model Worker. Deng Jiaxian died in Beijing on 29 July 1986, aged 62. 'Two Bombs Pioneer' (liangdan yuanxun) became the standard way the media and the public referred to him; General Zhang Aiping wrote an inscription with those words. On 18 September 1999 the Party Central Committee, the State Council and the Central Military Commission honoured 23 scientists for their contributions to the 'Two Bombs, One Satellite' programme, and Deng was posthumously awarded the Two Bombs, One Satellite Meritorious Medal.

Correspondence with Yang Chen-Ning

In the summer of 1971 Yang Chen-Ning made his first return visit to China, and Deng was among the friends and relatives he asked to see. According to the 2024 Science and Technology Daily article, as Yang was leaving Beijing he asked Deng at the airport whether rumours in the United States were true that Joan Hinton, an American who had come to China in 1948, had taken part in China's atomic bomb programme. Deng reported the question to his superiors; it went up to Zhou Enlai, who instructed that Yang be told the truth. Deng wrote a letter that night, which was delivered by courier the next day to Yang, then in Shanghai. According to Yang's account when donating his papers to Tsinghua University in 2021, the letter stated that apart from 'very limited Soviet assistance before the end of 1959', no foreigners had taken part in China's atomic weapons programme. It also said Hinton had not taken part in any work connected with making nuclear weapons, and closed with the line 'May we both live long, and share one road though a thousand miles apart'. Yang later recalled the episode in his essay 'Deng Jiaxian'. At a symposium held by Tsinghua University in September 2021 to mark his hundredth birthday, he said that he had not understood the phrase 'share one road' when he first read the letter, and only later grasped its deeper meaning.

In Western scholarship, China Builds the Bomb (Stanford University Press, 1988) by John W. Lewis and Xue Litai was one of the first English-language monographs to examine the history of China's nuclear weapons programme systematically; a Chinese translation was published by Atomic Energy Press in 1991.