An international group effort and a recently issued research paper may have just settled a century old physics debate. Quantum mechanics is, indeed, spooky. Quantum Entanglement, a part of quantum mechanics, tells us that two particles can be openly linked even across huge distances. If you measure the rotation of one particle, you will instantly know the spin of its entangled particle. Physicists have considered this behavior as “spooky” as it doesn’t follow our daily logic at all. Common sense tells us that objects across the cosmos cannot possibly be linked, but in the quantum world, they are. Quantum mechanics also states that properties of particles are only stable when the particle is perceived.
Several physicists, counting Albert Einstein, opposed this idea as it went in contradiction of the very nature of the actual world. In the 1930s when quantum mechanics was a developing field, Einstein was a supporter of “local realism,” saying that only nearby objects could affect each other. Einstein and several other physicists established the ‘hidden variables theory’ to clarify the spooky behavior. They claimed that our knowledge of quantum mechanics was partial and there might be unseen variables that we didn’t yet understand. In the 1960s a physicist called John Bell formulated a mathematical expression, called an inequality, to check for these so-called unseen variables. He comprehended that if these unseen variables did certainly exist, there would be a boundary to how linked the particles were. If they surpassed the set limit then the hidden variables did not exist. Though, the experiment, called as Bell’s Inequality, did not ultimately close the door on local realism. The tests involved entangled photons, which can get lost along the way, and researcher conducting the experiments might not detect all photons produced.
In the recent experiment, directed by Professor Ronald Hanson of Delft University of Technology in the Netherlands, we have two scientists, we will name them Alice and Bob, in two workshops 1.3 kilometers apart. Each laboratory has a diamond chip, containing an electron whose rotation was entangled with a photon. The photons were then directed to a third lab in between Alice and Bob, where a sensor records the entrance time. If two photons reached at the same time they would be entangled, resulting in the electrons being entangled also.
The experiment took time of nine days. In that time, scientists noted 245 positive entanglements. While other experiments over the last few decades have also maintained Bell’s limit, this new experiment acquires from their inadequacies to overcome experimental drawbacks. Previous test used incompetent detectors, only measuring a slight number of the particles passing through them. New experiments used near-perfect sensors, but the entangled particles were close enough to possibly connect. In the recent experiment, the team used high-quality sensors and measurements collected before the electrons could conceivably exchange signals with each other, creating it the first to close both loopholes.
The outcomes of this experiment have big consequences for the world of quantum cryptography, meaning entangled photons could possibly generate safe encryption keys. Terminating the loopholes would guarantee that computer systems could sense if anyone tried to interrupt the keys, as it would halt the entanglement and activate an alarm.