A group of European researchers,
consisting of institutions from France, Spain and Germany, has
published their work with quantum entanglement using electron
(Cooper) pairs, quantum dots and carbon nanotubes. Quantum
entanglement is a quantum state of matter where two particles,
typically photons or electrons, form a matched pair based on their
physical qualities such as up or down spin for electrons and
polarization for photons. When a pair of these particles becomes
entangled, quantum mechanics states that measuring one of the pair
will instantly force the unmeasured into a corresponding state,
regardless of the distance they have been separated by.
photonics work, researchers used wave guides and polarization filters
to form entangled photons, which can then be separated by a beam
splitter and measured individually. But for electrons, the work is
far more taxing. Measurements are more easily skewed by background
noise and leakage from the components of the test device.
solid-state device used to confirm electron quantum entanglement is
simple in design. A superconducting element is used to form
Cooper pairs. The pairs then move down the element towards a carbon
nanotube. Occasionally the pair is split by the nanotube and each
electron moves towards a separate quantum dot. In this time, one
electron’s spin can be measured, which infers the spin of its mate
instantaneously. These pairs can either be spin-correlated or
anti-spin-correlated (spinning in the same direction or opposite
directions), but the measurement of one always reveals the properties
of the other.
Quantum entanglement could be very useful in
theory, especially for quantum computing in the areas of security and
data transmission. Theoretically, data can be transferred over any
distance instantly and without any risk of security breech, however,
the entangled pair still has to be transferred through physical media
at this time.
quote: Measuring one member of the pair therefore tells you what spin the other member would have if it were also measured. The distance between the two particles is irrelevant.
quote: If each particle departs the scene of its "entangled creation" with properties that would unambiguously determine the value of the quality to be subsequently measured, then the postulated instantaneous transmission of information across space and time would not be required to account for the result of both particles having the same value for that quality.