Lev Vaidman (; born 4 September 1955) is a Russian-Israeli

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and Professor at

Tel Aviv University Tel Aviv University (TAU) is a Public university, public research university in Tel Aviv, Israel. With over 30,000 students, it is the largest university in the country. Located in northwest Tel Aviv, the university is the center of teaching and ...

, Israel. He is noted for his theoretical work in the area of fundamentals of

quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...

, which includes

quantum teleportation Quantum teleportation is a technique for transferring quantum information from a sender at one location to a receiver some distance away. While teleportation is commonly portrayed in science fiction as a means to transfer physical objects from on ...

, the Elitzur–Vaidman bomb tester, and the

weak value In quantum mechanics (and computation), a weak value is a quantity related to a shift of a measuring device's pointer when usually there is pre- and postselection. It should not be confused with a weak measurement, which is often defined in conjun ...

s. He was a member of the Editorial Advisory Board of ''The

American Journal of Physics The ''American Journal of Physics'' is a monthly, peer-reviewed scientific journal published by the American Association of Physics Teachers and the American Institute of Physics. The editor-in-chief is Beth Parks of Colgate University."Current ...

'' from 2007 to 2009. In 2010, the Elitzur–Vaidman bomb tester was chosen as one of the "Seven Wonders of the Quantum World" by New Scientist Magazine.

Personal life

He attended 45th Physics-Mathematics School in

Saint Petersburg Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

and was twice among the winners of the All-Soviet high school students Physics Olympiad (first place in 1971 and second place in 1972), and in 1972 scored 26th in the International Physics Olympiad in

Bucharest Bucharest ( , ; ) is the capital and largest city of Romania. The metropolis stands on the River Dâmbovița (river), Dâmbovița in south-eastern Romania. Its population is officially estimated at 1.76 million residents within a greater Buc ...

. Vaidman emigrated with his family to Israel at the age of 18. Prior to that, he studied for one year at Saint Petersburg University (then Leningrad University).

The Elitzur–Vaidman bomb tester

This thought experiment, subsequently conducted in the lab, is an example of

interaction-free measurement In physics, interaction-free measurement is a type of measurement in quantum mechanics that detects the position, presence, or state of an object without an interaction occurring between it and the measuring device. Examples include the Renninger ...

(IFM). IFM is the detection of the property of an object or its presence without any physical interaction between the observer and the object. Obtaining information from an object in such a manner is

paradox A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true or apparently true premises, leads to a seemingly self-contradictor ...

ical. The bomb tester works by employing an interferometer. When a photon is fired into the device, it encounters a half-silvered mirror positioned so as reflect the photon at a ninety-degree angle. There is a 50-50 chance it will be reflected or pass through. Due to the quantum properties of the photon, it both passes through the mirror and is reflected off of it. Now, the same photon is moving through two different parts of the device. The photon that passed through the mirror is now on the "lower path". It may or may not encounter a bomb, which is designed to explode if it encounters a single photon. The photon that was reflected off the mirror is now on the "upper path". Both photons next encounter a normal mirror. The ''lower-path'' photon is reflected ninety-degrees upward (if it did not detect a bomb). The ''upper-path'' photon is reflected back ninety degrees so that it is returned to its original trajectory. If the ''lower-path'' photon did not detect a bomb, it will arrive at a second half-silvered mirror at the same time as the ''upper-path'' photon. This will result in the single photon interfering with itself. A pair of detectors are positioned beyond the mirror in such a way that the photon's superposition collapses and the photon is observed to have either been on the upper path or the lower path, but not both. If the ''upper-path'' detector encounters the photon, then the photon "actually" took the upper path and no measurement was made of whether or not there was a bomb on the lower path. If, however, the ''lower-path'' detector encounters a photon, it can be determined that fifty percent of the time, there is a bomb on the lower path--''without actually encountering it''. Vaidman has argued that this lends support to the

many-worlds interpretation The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is Philosophical realism, objectively real, and that there is no wave function collapse. This implies that all Possible ...

Teleportation of continuous variables

Vaidman is a pioneer in the area of

. He has demonstrated that non-local measurements can be used to teleport unknown quantum states of systems with continuous variables.Zhang, L., Barhen, J., Liu H.
''Experimental and Theoretical Aspects of Quantum Teleporation''
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References

External links

Lev Vaidman's homepage

The Stanford Online Encyclopedia of Philosophy entry on the Many-Worlds Interpretation of Quantum Mechanics, by Lev Vaidman
* Lev Vaidman, ''Teleportation of Quantum States'', Phys. Rev. A 49, 1473-1476 (1994). Pre-prin
arXiv:hep-th/9305062
submitted 14 May 1993 {{DEFAULTSORT:Vaidman, Lev 1955 births Living people Israeli physicists Academic staff of Tel Aviv University Soviet emigrants to Israel Israeli Jews Soviet Jews Scientists from Saint Petersburg Quantum physicists Jewish Russian physicists

Personal life

The Elitzur–Vaidman bomb tester

Teleportation of continuous variables

See also

References

External links