(July 10, 2012) The problem
of long-distance transmission of quantum information is one of the biggest
obstacles to the realization of communications networks based on quantum
phenomena. LMU physicists have taken a significant step towards overcoming this
hurdle.
Transmission of quantum
information is based on the phenomenon of entanglement. Entanglement couples
the state of a particle, such as a photon (the quantum of light), to that of
another quantum object. The result is a non-classical type of correlation
between the two. For instance, a pair of photons can be entangled such that
their polarization - the orientation of the plane of oscillation of the
electric field – is undetermined. But if the polarization of one is later
ascertained, the other is always found to be in the opposite (“orthogonal”)
state, even if the measurement is made when the two are far apart.