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Portrait of Roy J. Glauber
Photo: Markus Pössel (User name: Mapos), Own work · CC BY-SA 3.0 via Wikimedia Commons

Nobel Prize in Physics · 2005

Roy J. Glauber

He wrote the quantum theory of light behind today's photon counters, quantum cryptography and the young field of quantum optics.

The Nobel citation: “for his contribution to the quantum theory of optical coherence”
Born
September 1, 1925, New York, NY, USA
Died
December 26, 2018, Newton, MA, USA
Shared with
John L. Hall, Theodor W. Hänsch
Affiliation at the time
Harvard University, USA

Physics prize

2005

Shared with 2 other laureates.

Age that year

80years

Born in 1925.

Sources cited

20

Fact-checked September 24, 2026.

  • At 18, while still a Harvard undergraduate, he joined Los Alamos and worked on critical-mass calculations for the first atomic bomb.
  • For more than 20 years he was the Ig Nobel ceremony's 'Keeper of the Broom', sweeping paper airplanes off the stage.
  • His prize-winning papers came out in 1963. The Nobel came 42 years later, when he was 80.
  • At a 1941 student science talk he shared the program with Baruch Blumberg, who later won a Nobel for finding the hepatitis B virus.
  • After his marriage ended he raised his son and daughter as a single father, and said the papers he lost to it were worth it.

The breakthrough

A quantum theory of what light detectors actually see

By 1960 physicists knew that light comes in tiny packets called photons. But they still used old wave-based math to describe beams of light, and in most everyday cases that worked. Then the laser was invented, and a puzzle appeared. In the 1950s two British researchers, Hanbury Brown and Twiss, had found that photons from ordinary light arrive at detectors in clumps. Would laser light do the same thing? In 1963 Glauber answered this with a full quantum theory of how a detector 'clicks' when it absorbs a photon. Every click changes the light that is left, so he described light by the patterns of clicks it produces across one or more detectors. Think of cars arriving at a toll booth. Light from a bulb is like traffic that arrives in bunches. An ideal laser is like cars that each show up at random, with no bunching at all. His framework also left room for light that is even more evenly spaced than random, like cars let through one at a time by a traffic signal. No wave-only theory can explain that pattern, now called antibunching, and later researchers who built on his theory went on to observe it. His tools, including 'coherent states' that describe laser light, became the standard language of the new field of quantum optics.[3],[4],[5],[6],[7]

“Raising those children and seeing them succeed was not an experience I would trade for the missing papers or any sort of recognition.”
Roy J. Glauber, From his Nobel autobiography, on raising his son and daughter alone after his marriage ended.[2]

What it meant for humanity

Glauber's work is mostly felt through the scientists and engineers who use it. The Nobel committee said his 1963 theory has been the basis for all later theoretical work on the subject, and that it helped create the field now called quantum optics. That field gives researchers ways to count single photons, to tell real quantum light from ordinary light, and to understand the lowest noise level any optical measurement can reach. The Nobel committee pointed to secure quantum communication, quantum computing and the detection of extremely faint signals as areas where this theory is needed. Engineers can remove most of the noise that comes from their equipment, but not the noise that comes from the quantum nature of light itself, so knowing where that floor sits matters for anyone building the most precise instruments.

His influence reaches beyond optics. In the 1950s he worked out how fast particles scatter off atomic nuclei. A simplified version of that work, the 'Glauber model', is still used to understand collisions of heavy nuclei at large accelerators such as Brookhaven's RHIC. Also in 1963, he published a model of how magnets change over time. Now called Glauber dynamics, it is widely used to simulate magnets and similar systems on computers.

Glauber also taught at Harvard for more than half a century, from freshman seminars to graduate courses. When he won the prize, Harvard's president praised the many students he had taught and mentored.

  • The Nobel committee said Glauber's 1963 theory became the basis for all later theoretical work on how light is detected, and the foundation of quantum optics.[5],[6]
  • The committee named secure quantum communication, quantum computing and detecting ultra-weak signals as uses that depend on this quantum view of light.[4],[5]
  • The 'Glauber model' of nuclear collisions, which grew out of his 1950s scattering theory, is used to analyze heavy-ion experiments at RHIC and later accelerators.[2],[16]
  • Glauber dynamics, his 1963 model of how magnets change over time, is now a widely used method for computer simulations in statistical physics.[17]
  • He taught at Harvard for more than 50 years, and his university praised him as a devoted teacher and mentor from first-year seminars to graduate courses.[8]

Impact in numbers

Glauber gave physics a clear quantum answer to a basic question: what do light detectors actually record? His 1963 theory explained why ordinary light arrives in clumps and ideal laser light does not. It also made room for light more evenly spaced than chance, which older theories could not describe and which later experiments found. The Nobel committee says it has been the starting point for all later theory in quantum optics. Today that field underpins single-photon experiments, quantum cryptography, research on quantum computers, and studies of the ultimate noise limits of precision measurement. Separately, his nuclear scattering theory survives as the Glauber model used at heavy-ion colliders, and Glauber dynamics is a standard simulation method. We give no benefit number because the path from a foundational theory to later technologies is too long and too shared to credit honestly. The one quantified claim is the harm side of his teenage work on the atomic bomb.

Fundamental scienceTechnologyCommunicationPeace

Each number is the laureate’s credited share of a real-world outcome, cumulative to 2025. The whole outcome, the share of credit, and the reasoning are shown so you can check the arithmetic. Outcomes shared with other laureates are counted once on the impact page.

  • HarmLow confidenceDirectSourced totalPeace

    Deaths from the atomic bombings of Hiroshima and Nagasaki within two to four months

    75–123

    deaths caused, credited share

    That is 0.05% of 150,000–246,000 deaths caused since 1945.

    How this number was built

    RERF estimates acute deaths within two to four months at 90,000-166,000 in Hiroshima and 60,000-80,000 in Nagasaki, so 150,000-246,000 in total. This is the same range used in the Feynman, Reines, Bethe and Aage Bohr profiles, and it excludes later cancer deaths. Scope is direct because his own calculations went into the weapon. Share 0.0005: from 1944 to 1946 Glauber was an 18-year-old undergraduate in the Theoretical Division, working on neutron diffusion and critical-mass problems and writing three secret reports. That is a role like Reines's in the same diffusion work (0.001), but more junior, so we halve it, which matches Aage Bohr. Thousands of others built the bombs, and US leaders chose to use them. Result: 150,000 x 0.0005 = 75 to 246,000 x 0.0005 = 123 deaths credited.[2],[8],[18]

    Sources: Radiation Effects Research Foundation (RERF); NobelPrize.org (from Les Prix Nobel, The Nobel Prizes 2005); Harvard Gazette

The double edge

At 18, Glauber joined the Manhattan Project. He spent about two years in the Los Alamos Theoretical Division working on neutron diffusion and critical mass, the amount of nuclear fuel a bomb needs, and wrote three secret reports. The bombs dropped on Hiroshima and Nagasaki killed an estimated 150,000 to 246,000 people within four months. He later said the news that he was working on a bomb disturbed him at first, and that he and his colleagues were driven by fear of a German bomb. In late interviews he said he had been a junior observer rather than a decision-maker, and he compared the atomic bombings to the conventional destruction of the war. His Nobel also drew a credit dispute. Supporters of the physicist E. C. George Sudarshan, who extended the theory in 1963, wrote to the Nobel committee arguing that Sudarshan's contribution had been undervalued. The committee's report notes that Glauber's key paper came first.

  • Major

    Critical-mass calculations for the atomic bomb

    From 1944 to 1946 Glauber worked in the Los Alamos Theoretical Division on neutron diffusion problems such as finding the critical mass, and wrote three lengthy secret papers. He watched the Trinity test flash from more than 100 miles away. The bombs used on Hiroshima and Nagasaki killed an estimated 150,000 to 246,000 people within two to four months. His role was junior, among thousands of contributors.[2],[8],[11],[18]

  • Minor

    Dispute over credit with E. C. George Sudarshan

    After the 2005 award, groups of physicists wrote to the Nobel committee arguing that Sudarshan's 1963 work had been undervalued and that he deserved more credit for what is often called the Glauber-Sudarshan representation. The committee's report notes that Glauber's key paper appeared first, and both men cited each other's work.[5],[12]

Against the odds

Glauber grew up in the United States, not in Europe, and he was never persecuted. His life was still shaped by hard times and by an America less open to Jewish people than it is today. When the stock market crashed in 1929, his father's employer went under and the family car was repossessed. His father found new work, but when the family settled in New York in 1931, they first had to crowd into his grandmother's Manhattan apartment. He built a telescope from junkyard parts and gifts, spending less than half of his $10 in savings, and later a prize-winning spectroscope. He joined the first classes at the new Bronx High School of Science, which admitted students by exam. In 1941 he went to Harvard on a Harvard Club scholarship. He later wrote that his family would not otherwise have dared to aim that high, and he lived among the scholarship students in the cheaper rooms. In the 1920s Harvard had moved to limit Jewish enrollment, and by 1933 Jewish students were back down to about 15 percent. During his childhood, the priest Charles Coughlin, whose radio audience at its peak was about 30 million, spread antisemitic ideas over the air. We found no record that Glauber himself faced antisemitism. His story is mainly one of a poor, curious boy lifted by free public schools, mentors and scholarships.

  • 1929

    Poverty

    The 1929 crash put his father's employer out of business, and the family car was repossessed. When the family settled in New York in 1931, they first crowded into an apartment with his grandmother and great-aunt, and he later built his first scientific instruments on almost no money.[2]

  • 1941

    Discrimination

    He entered Harvard in 1941 on a scholarship, living among the scholarship students in its less desirable rooms. Two decades earlier Harvard had moved to cap Jewish enrollment, and Jewish students were back down to about 15 percent by 1933. No source says he personally faced bias.[2],[19]

  • 1938

    Discrimination

    In the 1930s the radio priest Charles Coughlin, whose audience peaked at about 30 million regular listeners, spread antisemitic conspiracy claims. In 1938, when Glauber was 13, Coughlin's newspaper serialized the forged Protocols of the Elders of Zion.[20]

Jewish background

Both parents JewishRelationship to Jewish identity not documented

Glauber was born in New York City to Emanuel B. Glauber, a traveling salesman, and Felicia (Fox) Glauber, who had trained as an elementary school teacher. Reference works on Jewish laureates count him as Jewish. The Encyclopaedia Judaica (2nd edition, 2007) has an entry on him, and Jinfo lists him as Jewish without the note it uses for mixed ancestry. No source we found describes his parents' religious background directly, so the basis rests on these reference works. His Nobel autobiography and interviews describe a New York childhood during the Great Depression but say nothing about religious practice. How he himself related to his Jewish identity is not documented in the sources we found.[2],[13],[14],[15]

Key dates

  1. September 1, 1925

    Born in New York City. He spends his early years on the road with his parents while his father works as a traveling salesman.[1],[2]

  2. September 1938

    Enters the newly opened Bronx High School of Science as one of its first students.[2],[15]

  3. 1941

    Enters Harvard on a Harvard Club scholarship, about two years younger than most classmates.[2],[9]

  4. 1944

    At 18, joins the Los Alamos Theoretical Division and works on neutron diffusion and critical-mass calculations for the atomic bomb.[2],[8]

  5. July 1945

    Watches the flash of the Trinity test from Sandia Peak, more than 100 miles away.[2]

  6. 1946

    Returns to Harvard and graduates summa cum laude.[8]

  7. 1949

    Earns his PhD in physics at Harvard, nominally under Julian Schwinger. He then goes to Princeton's Institute for Advanced Study and works with Wolfgang Pauli in Zurich.[2],[3]

  8. 1951

    Fills in for Richard Feynman teaching quantum mechanics at Caltech. His work there leads to his theory of high-energy scattering off nuclei.[2],[15]

  9. 1952

    Returns to Harvard, where he spends the rest of his career.[2],[8]

  10. 1963

    Publishes his quantum theory of optical coherence, laying the foundation of quantum optics. The same year he introduces what is now called Glauber dynamics.[5],[17]

  11. 1976

    Named Mallinckrodt Professor of Physics at Harvard.[13]

  12. October 4, 2005

    Awarded half of the Nobel Prize in Physics for the quantum theory of optical coherence. John Hall and Theodor Hänsch share the other half.[3],[8]

  13. December 26, 2018

    Dies in Newton, Massachusetts, at 93, one of the last surviving witnesses of the Trinity test.[1],[9],[10]

Sources

  1. 1.Roy J. Glauber - Facts · NobelPrize.org (Nobel Prize Outreach)
  2. 2.Roy J. Glauber - Biographical · NobelPrize.org (from Les Prix Nobel, The Nobel Prizes 2005), 2005
  3. 3.Press release: The Nobel Prize in Physics 2005 · Royal Swedish Academy of Sciences, via NobelPrize.org, 2005
  4. 4.The Nobel Prize in Physics 2005 - Popular information: What limits the measurable? · NobelPrize.org, 2005
  5. 5.Advanced information on the Nobel Prize in Physics 2005: Quantum-mechanical theory of optical coherence; Laser-based precision spectroscopy · Royal Swedish Academy of Sciences, via NobelPrize.org, 2005
  6. 6.The Nobel Prize in Physics 2005 - Award ceremony speech by Stig Stenholm · NobelPrize.org, 2005
  7. 7.Roy J. Glauber - Nobel Lecture: One Hundred Years of Light Quanta · NobelPrize.org, 2005
  8. 8.Glauber wins Nobel Prize in physics, by William J. Cromie · Harvard Gazette, 2005
  9. 9.Roy Glauber, Nobel-winning physicist who applied quantum mechanics to optics, dies at 93, by Martin Weil (archived copy) · The Washington Post, via Internet Archive, 2018
  10. 10.Sad news: Roy Glauber, paper airplane sweeper and physicist of light, is gone, by Marc Abrahams (archived copy) · Improbable Research, via Internet Archive, 2018
  11. 11.Roy Glauber: The last witness to the Manhattan Project, by Daniel Mediavilla · El País (English edition), 2022
  12. 12.Nobel Doubts, by David Epstein · Inside Higher Ed, 2005
  13. 13.Glauber, Roy J. (Encyclopaedia Judaica, 2nd ed., entry by Michael Denman) · Encyclopaedia Judaica, via Encyclopedia.com, 2007
  14. 14.Jewish Nobel Prize Winners in Physics · JINFO.ORG
  15. 15.Roy J. Glauber · Wikipedia
  16. 16.Glauber Modeling in High Energy Nuclear Collisions, by M. L. Miller, K. Reygers, S. J. Sanders and P. Steinberg (Annual Review of Nuclear and Particle Science 57) · arXiv (Cornell University), 2007
  17. 17.Glauber dynamics · Wikipedia
  18. 18.Frequently Asked Questions: How many people died as a result of the atomic bombings? · Radiation Effects Research Foundation (RERF)
  19. 19.Getting In: the social logic of Ivy League admissions, by Malcolm Gladwell (on Jerome Karabel's The Chosen) · The New Yorker, 2005
  20. 20.The Radio Priest: Charles E. Coughlin and American Antisemitism · United States Holocaust Memorial Museum, Holocaust Encyclopedia

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 7 corrections made. How we check

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