Quantum entanglement – if the name itself doesn’t impress you what it allows ordinary laser beams to do will and the telecommunications world better pay attention. A team of physicists from City College of New York have developed a way for ordinary laser beams to mimic a phenomenon of quantum physics called quantum entanglement, which would double the data speed of laser communications.
Beware: Super Geekinese will be used in the following paragraphs so if large words frighten you turn back now!
Quantum entanglement might sound like a term straight out of Big Bang Theory or Star Trek but it is actually a very real, though very strange, phenomenon. Quantum entanglement occurs when particles such as electrons, photons interact physically and then become unconnected. The type of contact between this particles is such that each resulting member of a pair of particles is accurately designated by the same quantum mechanical state, which is unfixed in terms of important factors such as polarization, spin, momentum, position, etc. A pair or a group of particles such as these might have a property that is shared among them, in such a way that they cannot be considered independent from one another. In quantum mechanics, when you measure a certain property of a particle, such as its energy, you force the system to “collapse”: The value of the property will remain the same regardless. Get it? Good.
If that property is entangled, the collapse will affect all the particles in your quantum state, no matter the distance. Originally, this seemed a violation of special relativity, as the collapse could affect two particles at either end of the universe instantaneously. That would require speeds faster than light and relativity dictates that nothing can travel faster than light. In reality, no information is passed between the particles, so technically the laws of relativity are not broken because nothing is surpassing light speed. A lot of work is actually being done in this field and a growing number of physicists believe we’ll achieve faster-than-light communication by cleverly using quantum entanglement to our advantage. Its not so much breaking the laws of relativity as much as a workaround. Still with me? No wonder Einstein called this “spooky action at a distance”. In experiments, entangled photons are usually transported through optical fibres. But fibres absorb light, which keeps the photons from traveling more than a few hundred miles. This is where the New York team’s discovery can have major ramifications. Why use fibres when you can use light itself!
At the very core of quantum entanglement is something called “nonseperability” which is when two entangled particles are described by an unfactorized equation. What makes this interesting is that a simple laser beam’s shape and polarization can also be nonseperable. Think of that the next time you use a laser pointer. Light is made up of electromagnetic waves and light itself is polarized if those waves oscillate only on a specific plane. Light with different polarization is used in 3D movie theatres: Each eyepiece on the goggles that you are given have filters that let only a certain type of polarization through, thus creating the illusion of a three-dimensional image.(Bet you didn’t know that one!). So these researchers in New York were able to make the shape and polarization of a laser beam nonseparable by making the polarization of the light in the laser beam dependent on shape which they call a “vector beam”. Then using off-the-shelf components to ‘touch’ only it polarization, they showed it could be encoded as two bits of information. Surprisingly, this was twice as much information that could be encoded as when the laser beam was separable
In Simple Terms:
Because operations carried out on one of the entangled particles affect the state of its partner, no matter how far away it is, the two objects can be manipulated to act like two ends of a quantum telephone line, transmitting quantum information between two widely separated locations.
So what does this mean for telecommunications? Well, information in quantum entanglement transfers very fast and when most people describe this fascinating process, they’ll describe the information transfer as “instantaneous” or “near-instantaneous”. In 2014, a team of Chinese physicists entangled pairs of photons and came back and said that quantum entanglement transfers information at around 3-trillion meters per second or in other words you can say four orders of magnitude faster than light. Yeah, that is fast and by now you are probably seeing the implications of this for telecommunications. Lets look some more at real world application.
In 2009, from a site near the base of the Great Wall of China in the hills north of Beijing, China a team of physicists from the University of Science and Technology of China aimed a laser at a detector towards a rooftop nearly 10 miles away, then used the quantum properties of the laser’s photons to ‘teleport’ information across the intervening space! At the time, it was a world distance record for quantum teleportation, and a major step towards the team’s ultimate aim of teleporting photons to a satellite.If that goal is achieved, and it seems closer now given the success of the New York team, it will establish the first links of a ‘quantum Internet’ that harnesses the powers of subatomic physics to create a super-secure global communication network. China already plans to launch a satellite dedicated to quantum-science experiments. It will offer physicists a new arena in which to test the foundations of quantum theory, and explore how they fit together with the general theory of relativity — Einstein’s very different theory of space, time and gravity.