People tend to think they have a pretty good overview of how the physical world works, but on a small scale, things become incredibly strange. Particles are not always particles, and sometimes these particles (or waves) behave in a bizarre, counterintuitive way. One of the strangest features of physics is quantum entanglement. Glasgow University scientists have just taken the first photo that demonstrates the effect.
When two particles or molecules get caught on a quantum plane, they share one or more properties such as spin, polarization, or momentum. This effect persists even if you remove one of the entangled objects far from the other. Einstein famously called the entanglement "ghostly action in the distance". Einstein felt that the existence of an entanglement meant that there were gaping holes in quantum mechanical theory.
Scientists have successfully demonstrated quantum entanglement with photos, electrons, molecules of different sizes and even very small diamonds. However, the University of Glasgow study is the first to provide visual evidence of interdependence. The experiment used photons in entangled pairs and measured the phase of the particles – this is known as Bell entanglement.
The team produced photons with an ultraviolet laser, passing through a crystal that caused some of the photos to become entangled. A beam splitter turned the beam into two equally sized "arms," with some of the entangled photos taking different paths. Since they were involved in each other, they also shared the same phase after their separation.
One of these photons passes through a liquid crystal material that undergoes four phase transitions (0.45, 90) and 135 degrees. The team used a high-sensitivity camera to take pictures of the entangled photon that had not passed through the filter. However, it showed the same phase transitions as its partner. The picture above shows the entangled pair in a 45 degree phase.
Scientists believe that quantum entanglement could have applications for quantum computing, data transmission, and even teleportation. For all of this to work, we need to examine the entanglement more closely. The Glasgow University experiment could open the door to new forms of imaging that help us deal with this creepy action from a distance.