Daniel Greenberger

Distinguished Professor

Main Affiliation






Daniel Greenberger


Ohio State Univ 1960-61 Asst. Prof. Physics
Univ. of California, Berkeley 1962-63 Asst. Prof. Physics
City College of New York 1963-Present Asst. Prof,
Assoc. Prof., Prof. Physics
City College of New York 2010-2013 M. W. Zemansky
Chair in Physics Physics
City College of New York 2013-Present Distinguished Professor


Univ. of California, Berkeley 1964-68 summers Assoc. Prof. Physics

Univ. of Washington, Seattle 1969 summer Assoc. Prof. Physics

Univ. of Mass., Amherst 1970 summer Assoc. Prof. Physics

Mass. Inst. of Technology 1979-80 Visiting Prof. Physics

Univ. of Paris VIII, St. Denis 1986- April Exchange Prof. Lib. Arts

Technical Univ. of Vienna 1986-Fall Visiting Prof. Physics

B. Research

Institution Dates Rank .

Univ. of California, Berkeley 1961-1962 NSF Postdoctoral Fellow

Oxford Univ., England 1971-Spring Vis. Scientist (Sabbatical)



Mass. Inst. of Technology 1979-80 Visiting Prof. (Sabbatical)

Mass. Inst. of Technology 1980-1988 Adj. apptmt. as Visiting Scientist

Univ. of California, 1984-Summer Visiting Scientist

Santa Barbara, Inst. for Theoret. Phys.

Tech. Univ. of Vienna 1986-Fall Fulbright Vis. Prof.

Max Planck Inst. for 1988-spring Humboldt Vis. Prof.

Quantum Optics, Munich

Univ. of Vienna 2001-Spring Visiting Prof. (Sabbatical)

Hampshire College, Amherst 1989-present Adj. Visiting Prof.

Univ. of Vienna 2003-July Visiting Scientist

NUS-Singapore, Oxford Univ, 2010-Fall Visiting Prof. (Sabbatical)

Univ. of Ulm, Univ. of Vienna


I went to the Bronx High School of Science, where I graduated in 1950, in a class

that included the two Nobel Prize winners Steven Weinberg and Sheldon Glashow. The

same class included the APS Buckley Prize winner and former president of the APS,

Myriam Sarachik, as well as other well known physicists Gary Feinberg and Morton

Sternheimer. It was a good year for physicists.


I went to MIT as an undergraduate, and wrote my thesis under Prof. Laszlo Tisza,

graduating in 1954. I went to graduate school at the Univ. of Illinois, getting a Masters degree in 1956, and my Ph. D. in 1958. However, after I passed my qualifying exams in

1956, my thesis advisor, Prof. Francis Low, moved on to MIT, so I followed him there

and spent two years writing my Ph. D. thesis at MIT, although my degree comes from



When I graduated, I had to spend two years in the US Army, to fulfill an ROTC

obligation, since they were nice enough to let me finish graduate school first. I served

most of my time at a physics research lab., officially connected to the NSA, outside of

Washington, DC, next to the U. of Maryland campus, and got to know the Maryland

faculty. (The Army trained me as a cryptanalyst, which I never dreamed could be useful

in my career. But one of the subjects I am interested in today is quantum cryptography,

so you never know.)


Then I went to Ohio State University for one year, and won an NSF post-doc.

fellowship, and went to Berkeley to work in Geoffrey Chew's group, from 1961 to 1963.

All this time I was a high-energy theorist. I was hired by CCNY in Sept. 1964, and have

been there ever since.


But I soon changed fields, becoming interested in gravity, and thought up an

experiment to test the equivalence principle with neutrons. I went to see Prof. Cliff Shull

at MIT around 1970 to see if he could do the experiment. He thought so, but the MIT

reactor was down for two years. In the meantime, Roberto Collela, Al Overhauser, and

Sam Werner, independently thought of a better way to do the experiment and did it

beautifully, using the neutron interferometer, which was new at that time. I then started a

collaboration with Al Overhauser, and we have been good friends ever since. In 1978, I

went to a conference at Grenoble in France, where they had the world's biggest nuclear

reactor, and met Cliff Shull again, and Mike Horne, and Anton Zeilinger there. They

were all collaborating at MIT, and I started to go up there visiting them regularly, and

becoming part of their group, and we have been collaborating for 30 years. In 1980, I

spent a yearat MIT on sabbatical.


This kept up until the middle 80's when Prof. Shull retired, and MIT stopped

doing neutron diffraction. Prof. Shull won the Nobel Prize shortly after he retired.

Anton Zeilinger moved on to the Atominstitut at the T.U. in Vienna when Prof. Shull

retired, and I went to visit him there on sabbatical with a Fulbright grant in 1986. There

we discovered the GHZ (Greenberger-Horne-Zeilinger) theorem, a much improved

version of Bell's theorem in quantum mechanics, although we did not publish it until

1989. Prof. Zeilinger moved on to Innsbruck, and started a quantum optics lab. I won a

Humboldt senior scientist award and went to Munich in 1988, to work with Prof. H.

Walther at the Max Planck Inst. in Garching.


Since this time I have been working on fundamental problems in quantum theory,

mostly using quantum optics. Prof. Zeilinger started a quantum Optics lab. at the Univ.

of Vienna around 1990, and I have been visiting there regularly and collaborating with

his group. Some other high points have been that a two issue festschrift was published

for me by the Journal Foundations of Physics on my 65th birthday, and a conference on

"Fundamental Problems in Quantum Mechanics" was held in honor of my 75th birthday

at the University of Vienna, in 2009. (Also honored was Helmut Rauch, co-inventor of

the Neutron Interferometer, on his 70th birthday,) I was elected a fellow of the American

Physical Socilety, and also a foreign member of the Austrian Academy of Sciences, the

Nobel Prize Committee in physics hired me as a consultant, and Prof.Zeilinger and I

founded the topical group on Quantum Information for the APS, which at last count had

well over 600 members. In 2009, I was elected to hold the Mark W. Zemansky Chair in

Physics, at CCNY, a memorial chair for a very good physicist and a great teacher. In the

fall of 2011, I went on sabbatical for one semester, during which time I had a renewal of

a senior scientist award from the Humboldt Foundation, and worked for two months in

Ulm, Einstein's birthplace. The rest of the sabbatical was spent in Singapore, Oxford,

and Vienna.


I have also organized a number of meetings on quantum mechanics, including two

large ones, one of which honored Eugene Wigner, and the other honored John Wheeler. I

am also on the editorial boards of a number of journals, and am still doing research on

entangled states in quantum mechanics.


Massachusetts Inst. 1950-1954 B. S. Physics 1954
of Technology
University of Illinois 1954-1958 M. S. Physics 1956
Ph. D. Physics 1958

Courses Taught

Graduate Physics:
Electricity and Magnetism
Quantum Mechanics
General Relativety

Undergraduate Physics:

Quantum Mechanics


Statistical Mechanics

Mechanics and Electricity and Magnetism


Astronomy for Non-science Majors

General Physics ("Physics for Poets")
General Physics for Scientists and Engineers
Physics of Music
High School Enrichment Program 

Quantum Computation



Remedial Mathematics

History and Philosophy of Science and Technology, I and II

History and Philosophy of Quantum Theory (with K. Irani)

Public Policy and Human Values (LAPP Program)

Science, Technology, and Ethics (Interdepartmental Course)

Science and Public Policy (LAPP Program, interdisciplinary)

Science, Technology, and Society (Senior interdisciplinary "capstone" course)

Science Core Course-Workers Education Program (with J. Roze)

First Physics Prof. to teach in the FIQWS program (English)

Research Interests

neutron interferometry; quantum theory; relativity; history and philosophy of science

Fields of Research: (Theoretical) Fundamental problems in Quantum Theory, Neutron

Interferometry, Gravitational and Relativistic Physics

A. (with M. Horne and A. Zeilinger). We proved a generalization of Bell's Theorem which

is theoretically much simpler than previous work on the subject. A number of people have

exploited this work theoretically, and experimentally. The necessary states (GHZ states) have

been experimentally produced and are now being used in Quantum Cryptography and Quantum


B. Because of the expansion of our work from neutrons into optics, I have been learning

optics, notably lasers. That is the reason for my stay at the Quantum Optics laboratory in

Garching, and my last graduate student had a significant optics involvement in his thesis. The

technique, called "parametric down-conversion", is a direct analog of some work we have done

with multi-particle quantum systems, and Zeilinger's group has gotten directly involved, both

experimentally and theoretically in the subject of "entangled states".


C. I have also been involved in studying a restricted form of time-travel in quantum

theory. There is also much work on this area in general relativity, but I believe that

quantum theory itself is a natural place in which to look for such behavior, as already one

can see such phenomena as quantum teleportation.

D. I am working on a study of the relativistic effects possible with atomic and neutron

interferometers, and the differences between these techniques (with W. Schleich, and E. Rasel).


Greenberger, D.; Schleich, W, ; Rasel, E. Neutron and Atomic Interferometers, Foundations of Quantum Mech., conference at Pecs, Hungary, N/A (2012). CCNY Authors assigned: Greenberger, D.

Greenberger, D.; Schleich, W.; Rasel, E. Relativistic Effects in Neutron and Atomic Interferometry, Workshop at Bad Honnef, Germany, N/A (2012).
CCNY Authors assigned: Greenberger, D.

Greenberger, D. The Tic-Tac-Toe Theory of Gravity, Foundations of Physics, Found. of Physics, 42, P. 46, 2012. (2012).
CCNY Authors assigned: Greenberger, D.

Greenberger, Daniel "The Tic-Tac-Toe Theory of Gravity", Foundations of Physics, 42, 46-52 (2012) (2012).
CCNY Authors assigned: Greenberger, Daniel

Greenberger, Daniel Colloquium on Proper Time, Colloquium at U. of North Carolina, N/A (2011).
CCNY Authors assigned: Greenberger, Daniel

Greenberger, D; Ed. by Schlosshauer, M. Interview for a chapter of the book "The Quantum Interviews", The Quantum Interviews, by M. Schlosshauer, Springer, N/A (2011).
CCNY Authors assigned: Greenberger, D.

Greenberger DM A conference will be held in my honor this summer, Fundamental Questions in Quantum Theory, N/A (2009).
CCNY Authors assigned: Greenberger DM

Greenberger DM, Horne M, Zeilinger A A Bell Theorem I, Phys. Rev. A, 78, 022110 (2008).
CCNY Authors assigned: Greenberger DM

Greenberger DM, Horne M, Zeilinger A, Zukowski M. A Bell Theorem II, Phys. Rev. A, 78, 022111 (2008).
CCNY Authors assigned: Greenberger, DM

N/A on editorial board or managing editor on enclosed journals, Foundations of Physics, Fortschritte der Physik, IJQI, N/A (2008).
CCNY Authors assigned: Greenberger DM

Greenberger D. The Tic-Tac-Toe Theory of Gravity, Proceedings of the 6th Workshop on Mysteries, Puzzles, and Paradoxes in Quantum Mechanics, Gargnano (Bonifacio, R., Englert, B. G. and Severio, S., eds.) (in press)., (2007).
CCNY Authors assigned: Greenberger

Dahl J. P., Greenberger D., et al Adventures in s-waves, Fortsch. der Phys. (in press)., (2007).
CCNY Authors assigned: Greenberger

Greenberger D., Scully M., et al Planck, Quantum Fluctuations, and Bose-Einstein Condensation, Progress in Optics, vol 50, E (Wolf, ed.) Elsevier (in press), (2007).
CCNY Authors assigned: Greenberger

Greenberger, D. M. Quantum Mechanics Looks at Time Travel (With Svozil, K.): Chapter 4 of the book Quo Vadis Quantum Mechanics, Elitzur, A. et al., eds, Springer, Quo Vadis Quantum Mechanics, (2005).
CCNY Authors assigned: Greenberger

Greenberger, D. M. A Bell Theorem Without Inequalities for Two Particles, Using Efficient Detectors, Phys. Rev. A, 78, 022110 (2005).
CCNY Authors assigned: Greenberger

Greenberger, D. M. A Bell Theorem Without Inequalities for Two Particles, Using Inefficient Detectors, ArXiv.org, arXiv:quant-ph/0510207 (2005).
CCNY Authors assigned: Greenberger