Friday, September 21, 2007

Imaging Entanglement

How a conventional tool of material science — neutron beams produced at particle accelerators and nuclear reactors — can be used to produce images of the ghostly entangled states of the quantum world.

Thank you to RocketRoo for this post:

This press release from University College London, shows a computer-generated image based on neutron-beam scattering of (anti-ferro)magnetically aligned electron spins which are entangled. So, now we have the complementary set as far is this blog is concerned: imaging with entanglement (e.g., quantum ghost imaging with photons), and imaging of entanglement (with neutrons).

Aside: The astute reader may be wondering how neutrons (which are electrically neutral by definition) can be used to image entangled electrons that are negatively charged. How can there be any interaction between these particles; a necessary condition for imaging anything?

Although electrically neutral (as is an atom that is not ionized), the neutron is a baryon and therefore composed of 3 quarks (see, 1 of which (the 'up' quark) has +2/3 the magnitude of the electron charge and the other 2 quarks ('down' quarks) have 1/3 the electron charge. If the neutron comes close enough to an electron the individual charges will begin to influence each other and cause scattering.

It's also blog-worthy that just last week it was reported that the neutron has a negative charge both in its inner core and its outer region with a positive charge sandwiched in between to make the particle electrically neutral. Previously, Fermi had proposed in 1947 (pre-quark model) that the neutron core was postitive with the outer region negative.

Credits: RocketRoo