Steven Chu

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Steven Chu (2009)

Steven Chu ( Chinese  朱棣文 , Pinyin Zhū ​​Dìwén ; born February 28, 1948 in St. Louis , Missouri ) is an American physicist.

He received the Nobel Prize in Physics in 1997 . His main area of ​​expertise is influencing atoms with lasers . He was director of the Lawrence Berkeley National Laboratory until his appointment as Secretary of Energy and holds professorships at Berkeley and Stanford .

In the cabinet of the US President Barack Obama, Chu held the office of energy minister from 2009 to 2013 .


Chu comes from a Chinese-born academic family who immigrated to the USA in 1943 via France . His father was a chemistry professor at Brooklyn Polytechnic , and Chu grew up nearby in Garden City. Chu initially studied at the University of Rochester , where he received his bachelor's degree . He then moved to the University of California, Berkeley with the intention of specializing in theoretical physics . Instead, at Eugene Commins , he dealt with the measurement of parity violations of the magnetic dipole transition ( forbidden in quantum electrodynamics ) in thallium atoms , which were possible in the Standard Model according to the electroweak theory (the original proposal for such experiments came from Claude Bouchiat and Marie-Anne Bouchiat in France 1974) and manifested themselves in a weak asymmetry of the absorption of right and left polarized light. For the experiment, Chu had to work intensively on building lasers. The experiment took some time to complete, and during this time he became a post-doc in 1976 - his experimental work was recognized as an adequate qualification. The group published its first results in 1979, but at that time neutral currents had already been demonstrated at the SLAC in high-energy physics.

From 1978 he worked at Bell Laboratories in Murray Hill (New Jersey) , where he began with experiments to precisely measure the spectra of positronium , the "hydrogen atom" of quantum electrodynamics , consisting of positron and electron. The experiment (with Allen Mills) was successful, but also took several years to complete. It was one of the most precise experiments in quantum electrodynamics at the time.

In 1983 he became head of the department for quantum electronics research at the Bell Laboratory in Holmdel . At that time he planned to deal with solid-state physics (picosecond laser pulses to investigate exciton excitations), but then (inspired by the work of his colleague Arthur Ashkin at Bell Labs, who had been working on it since 1970), he started developing optical traps and their further development with laser cooling processes led to the “capture” of atoms, which ultimately earned him the Nobel Prize.

In 1987, he succeeded Theodor Hänsch as Professor of Physics and Applied Physics at Stanford University . There he headed the physics department from 1990 to 1993 and 1999 to 2001 and also turned to biophysical research.

In 2004 he became director of the Lawrence Berkeley National Laboratory and also accepted a professorship at the University of California, Berkeley.

From January 20, 2009 to April 22, 2013, he was Secretary of Energy in the Obama administration .

Speaking to both Houses of Congress on health care reform in 2009, Chu was Designated Survivor . In the event of an attack on the Capitol, he would have been the highest-ranking survivor and would have succeeded Barack Obama as president. Chu was again Designated Survivor at the State of the Union Address in 2013 .

Currently, Chu is William R. Kenan, Jr., Professor of Physics and Professor of Molecular & Cellular Physiology in the Medical School at Stanford University. He is also a member of the Bio-X Biosciences Institute and the Wu Tsai Neurosciences Institute in Stanford.


Barack Obama and Steven Chu (2009)

Chu developed numerous methods and devices for optical and atomic physical measurements. Using stabilized lasers, he measured the parity violation in thallium atoms and with Doppler-free two-photon spectroscopy he examined positronium and muonium (with Mills he measured the difference between the 1s and 2s levels of positronium in 1982 with an accuracy of a few parts to a billion) . His most important scientific achievement from the mid-1980s was the laser cooling of atoms. It is a central component of magneto-optical atom traps .

Chu later worked on refining these methods for atomic clocks based on the fountain principle and Bose-Einstein condensates . He participated in highly precise measurements of the gravitational constant and fine structure constant and used some of his optical methods in biophysical investigations, such as the manipulation of individual DNA molecules with optical tweezers (Optical Tweezers, 1989) or in polymer dynamics .

In 1982 he and Wong showed the possibility of the propagation of pulses in absorbing media with a group speed that is greater than the speed of light in the medium.

At present, Chu is mainly working on research on biophysical topics (such as the synthesis and functionalization of nanoparticles for the in vivo mapping of cellular processes) and physical problems relevant to energy and environmental issues (such as the development of batteries based on lithium and sulfur, new methods for the electrochemical splitting of water, the reduction of carbon dioxide emissions and the extraction of lithium from salt water).

He was one of the first to sign the petition for Project Steve , a campaign that advocates the education of conventional scientific understanding of evolution in schools, opposing the US popular alternative concepts of creationism and intelligent design .

Commitment to energy supply and climate change

Steven Chu (right) and Fatih Birol (center) at a conference at the University of Oxford

Chu has long advocated intensifying research in renewable energies and advancing nuclear power , believing that a shift away from fossil fuels is essential to combat global warming .

Chu also warned that global warming could make farming impossible in the state of California within this century. He is a member of the Copenhagen Climate Council, an association of business and science representatives that was created to provide an impetus for the UN Climate Change Conference in Copenhagen in December 2009.

Chu played a key role in drafting the successful application for the Energy Biosciences Institute , a $ 500 million BP- funded joint venture between the University of Berkeley, the Lawrence Berkeley Lab and the University of Illinois . This sparked controversy at Berkeley with those who fear the collaboration could damage the university's reputation for academic integrity.

Awards and honors

Chu received the Herbert P. Broida Prize for Laser Spectroscopy from the American Physical Society in 1987 , the König Faisal Prize for Natural Sciences in 1993, the William F. Meggers Award from the Optical Society of America in 1994 and the Arthur L. Schawlow Prize in Laser Science the APS and in 1995 the Humboldt Research Prize of the Alexander von Humboldt Foundation , which also organized a Wolfgang Paul lecture , which he held in 1998 at the Physics Institute of the University of Bonn . In 1996 he received a Guggenheim scholarship . He is a member of the National Academy of Sciences , the American Academy of Arts and Sciences since 1992 and the American Philosophical Society since 1998 . In 2014 he was elected to the Royal Society and is also a member of Academia Sinica , the Chinese Academy of Sciences and the Korean Academy of Science and Technology . He has been a full member of the Pontifical Academy of Sciences since 2018 . Chu have received over 30 honorary doctorates, including from Boston University (2007), Harvard University (2009) Washington University in St. Louis , Yale University and the University of Strathclyde (all 2010), Australian National University (2014) Dartmouth College (2015) and Amherst College (2018).

1997 Chu got together with William D. Phillips and Claude Cohen-Tannoudji the Nobel Prize in Physics for the cool and trap atoms with laser light .

Web links

Commons : Steven Chu  - collection of images, videos and audio files


  1. ^ R. Conti, P. Bucksbaum, S. Chu, E. Commins, L. Hunter: Preliminary Observation of Parity Nonconservation in Atomic Thallium . In: Physical Review Letters . tape 42 , no. 6 , 1979, pp. 343-346 , doi : 10.1103 / PhysRevLett.42.343 .
  2. Steven Chu, Allen P. Mills Jr., John L. Hall : Measurement of the Positronium 1 3 S 1 -2 3 S 1 Interval by Doppler-Free Two-Photon Spectroscopy . In: Physical Review Letters . tape 52 , no. 19 , 1984, pp. 1689-1692 , doi : 10.1103 / PhysRevLett.52.1689 .
  3. Steven Chu, JE Bjorkholm, JM Dziedzic, A. Ashkin: Observation of a single-beam gradient force optical trap for dielectric particles . In: Optics Letters . tape 11 , no. 5 , 1986, pp. 288-290 , doi : 10.1364 / OL.11.000288 .
  4. Steven Chu, L. Hollberg, JE Bjorkholm, Alex Cable, A. Ashkin: Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressure . In: Physical Review Letters . tape 55 , no. 1 , 1985, pp. 48-51 , doi : 10.1103 / PhysRevLett.55.48 .
  5. ^ Jason Socrates Bardi: Focus: Landmarks: Laser Cooling of Atoms . In: Physical Review Focus . tape 21 , no. 11 , April 2, 2008, doi : 10.1103 / physrevfocus.21.11 .
  6. ^ A b Steven Chu: Biography., accessed November 29, 2018 .
  7. Steven Chu, JE Bjorkholm, A. Ashkin, A. Cable: Experimental Observation of Optically Trapped Atoms . In: Physical Review Letters . tape 57 , no. 3 , 1986, pp. 314-317 , doi : 10.1103 / PhysRevLett.57.314 .
  8. ^ EL Raab, M. Prentiss, Alex Cable, Steven Chu, DE Pritchard : Trapping of Neutral Sodium Atoms with Radiation Pressure . In: Physical Review Letters . tape 59 , no. 23 , 1987, pp. 2631-2634 , doi : 10.1103 / PhysRevLett.59.2631 .
  9. S. Chu, S. Wong: Linear Pulse Propagation in an Absorbing Medium . In: Physical Review Letters . tape 48 , no. 11 , 1982, pp. 738-741 , doi : 10.1103 / PhysRevLett.48.738 .
  10. ^ Current Research and Scholarly Interests. Stanford University, accessed November 30, 2018 .
  11. Steve Mirsky: Bringing in the Steves. In: The Scientist. February 17, 2003, accessed November 30, 2018 .
  12. ^ Project Steve. National Center for Science Education, accessed November 30, 2018 .
  13. ^ Professor Steven Chu: Winner of the 1993 KFP Prize for Science., accessed November 29, 2018 .
  14. a b Steven Chu. OSA, accessed November 29, 2018 .
  15. 1994 Arthur L. Schawlow Prize in Laser Science Recipient: Steven Chu. APS, accessed on November 29, 2018 .
  16. 1998: Steven Chu. University of Bonn, accessed on November 29, 2018 .
  17. Steven Chu, Fellow: Awarded 1996. Guggenheim Foundation, accessed November 29, 2018 .
  18. ^ Nomina di Membro Ordinario della Pontificia Accademia delle Scienze. In: Daily Bulletin. Holy See Press Office , October 20, 2018, accessed October 20, 2018 (Italian).
  19. ^ Nobel Prize Winner Steven Chu to Speak at Boston University Commencement. Boston University, accessed November 29, 2018 .
  20. In Esteemed Company. In: Harvard Magazine. June 4, 2009, accessed November 29, 2018 .
  21. Five to receive honorary degrees . Washington University.
  22. Leah Finnegan: Celebs Converge At Yale's Graduation Ceremony (PHOTOS). In: Huffington Post. May 24, 2010. Retrieved November 29, 2018 .
  23. ^ Honorary degrees for 3 Nobel laureates. University of Strathclyde, November 4, 2010, accessed November 29, 2018 .
  24. ^ ANU honors Professor Steven Chu. ANU, December 8, 2014, accessed on November 29, 2018 .
  25. Steven Chu (Doctor of Science). Dartmouth College, June 14, 2015, accessed November 29, 2018 .
  26. Nate Procter: Steven Chu awarded honorary degree, offers prediction of hope. In: Daily Collegian. March 22, 2018, accessed November 29, 2018 .
  27. Information from the Nobel Foundation on the 1997 award ceremony for Steven Chu (English)