International Relations. A self-Study Guide to Theory

particle, resulting in a definite physical value, will simultaneously cause the 
other particle to take the correlate value. This correlation has even been ob-
served when the entangled parts are located far away from each other.
Recently, experiments on quantum teleportation have demonstrated this 
correlation for a distance of 143 km (see FAZ from 23 August 2012 – Rekord-
jagd beim Beamen – for a German language explanation or ScienceDaily 
from 05 September 2012: Quantum Physics at a distance for more detail in 
English). The findings of these experiments were also published in the jour-
nal Nature (vol. 11472, 2012).

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Quantum teleportation is an application of quantum entanglement that has 
found its way into quantum technology. In this case, quantum information is 
“transmitted” without the information “crossing space”. This seeming impos-
sibility can occur because of entanglement; once the properties of the first 
particle have been fixed, the “other” particle takes correlate properties. Be-
cause of entanglement, there is “nothing” to be transmitted. This experi-
mental evidence of quantum entanglement disprove Einstein’s classical view 
of physical particles, which had defined properties independent of each other 
and independent of the measurement process. Interconnectedness between 
physical properties is fundamentally incompatible with the atomist view of 
single, separated entities at the heart of classical physics. Einstein fundamen-
tally disbelieved in the findings of quantum physics, expressed in his famous 
comment that entanglement was a “spooky action at a distance” and, as relat-
ed to the probabilistic interpretation of the wave function, his oft-quoted 
“God does not play dice”.
Quantum entanglement has now been experimentally proved and recog-
nized as a valid feature of quantum mechanics. The focus now lies instead on 
technological research that will enable us to utilize the knowledge for com-
munication and computing. 
In fact, a great deal of today’s technology and industry is already based 
on the findings of quantum physics. Above all, quantum technology is used 
in communication technology and information processing. Quantum technol-
ogy has advanced to such an extent that it has been split into subfields such 
as quantum mechanics, quantum information technology, quantum optics, 
quantum computing, and quantum cryptography. For example, quantum im-
aging as a subfield of quantum optics is used to take images of objects with a 
resolution far beyond what classical optics can achieve. Other subfields in-
clude quantum lithography, quantum electronics and quantum nanomechani-
cal devices, quantum mathematics, and quantum chemistry. It has also been 
predicted that the quantum internet will be the next generation of the infor-
mation-processing platform (see Ma/Herbst et al 2012). Therefore, it will 
likely not surprise you that, starting in 1918 with Max Planck, and later 
Schroedinger, Bohr and Heisenberg, many quantum physicists have received 
the Nobel prize for physics for their contributions to this field. In the most re-
cent example of this trend, the 2012 prize went to Haroche and Wineland for 
their work with quantum systems. For readers interested in expanding their 
knowledge of this area, Milburn (1997) wrote one of the first books on the 
technological applications of quantum physics and provides an excellent 
overview of quantum technology. 

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Summary 
In classical physics (and as still believed by Einstein), all particles have de-
fined properties that are independent of measurement. The properties are 
“fixed”; that is, they are given before the measurement process. We can use 
measurement to know about the properties of the particles in an objective 
manner.