We get amazed when a magician plays tricks like pulling out a rabbit from an empty hat or coin from someone’s ear etc. They can even make an aeroplane disappear within fraction of a second (a trick which is actually performed with the help of mirrors). Now imagine: what if we could disappear from one place and reappear at a different place instantly? The consequences would change the whole world. We would not require any mode of transportation like trains or planes. Earth would become heaven for couples in long distance relationships. Going on a holiday would become a lot easier and cheaper. Besides its advantages there would be some disadvantages as well. Criminals can disappear after committing a crime. The Army would be able to penetrate enemy lines without being noticed.
Teleportation is the ability to transport a person or an object instantly from one place to another without traversing the distance between those places. It has been a part of science fictions for many decades. But, is teleportation possible? If so, what is the science behind it? How far are we in creating such a technology? The answers to these questions lie in Quantum physics and in this article I will try to answer them.
Quantum world-where common sense breaks down!
Quantum physics describes the nature and interaction of particles at atomic and sub atomic level. We all are familiar with Newton from our high schools. Newton’s three laws in physics were the foundation of physics before quantum physics was formulated. According to Newton matter around us is made up of tiny hard particles. These particles can’t change their motion unless a force is applied on them. They can’t suddenly disappear and reappear at a different place. Hence in classical physics, which is based on Newton’s laws, teleportation is impossible.
Quantum physics tells us that there is no such thing as particle or a wave. The concept of wave-particle duality in Quantum physics states that a particle e.g. electron can act as waves and waves e.g. light (which is a form of electromagnetic waves) can act as particles called photons. So in other words we can also say that light beam is a train of particles called photons. There are many experiments that confirm this phenomenon. Now the question is, if there are waves associated with particles, what are these waves? The answer is ‘Probability Waves’. To understand that we need to know Heisenberg’s uncertainty principle.
There is a famous joke on Quantum physicists which is as follows: ‘Quantum physicists are bad at sex, as when they find a spot they don’t have proper momentum and when they have momentum they can’t find a spot. You can only understand this joke if you know what the uncertainty principle states. We will understand this principle by a simple example. To find the speed of a tennis ball in a dark room we could take two flashbulb photographs, measure the distance the ball travels between the photos, the time between them, and calculate «distance/time = speed». When we take a photograph, some flashbulb photons (particles of light which we discussed in the paragraph above) hit the ball (which reflects them back to the camera film) and a tiny amount of photon momentum is transferred to the ball. But the ball’s mass is so large that this momentum doesn’t have a significant effect on the ball’s motion.
Now imagine the same experiment but instead of a ball you have an electron which is about a Trillion times lighter than the ball. When hitting the ball, the photon will change the motion of an electron in a significant and unpredictable way. These limitations are imposed by nature, not by a lack of technology or cleverness. No matter how carefully we build measuring instruments and plan experiments, we cannot make measurements that are more precise than is allowed by the uncertainty principle. According to this principle, neither the exact position, nor the exact velocity of a particle can be measured simultaneously.
The consequence of this principle is that when we measure a certain particle, there is always a probability of finding a particle at some position, as we don’t exactly know where the particles position is. This probability of finding a particle in a region of space is described by the mathematical function called ‘wave function’. The larger the amplitude of a wave function is, the higher is the probability of finding the particle at that point. In short it means that there is a probability that an electron will be in many places at the same time. The concept of probabilities in quantum physics breaks all the laws of common sense, but this is how the nature works at nano level.
Teleportation using Quantum Entanglement
Imagine two electrons vibrating in unison (a state called coherence). If we take one of them as far away as billions of kilometres, they will still remain in unison. It seems like there is an invisible connection between the two electrons. If something happens to one electron, the information is immediately transferred to the other. This phenomenon of particles vibrating is known as quantum entanglement.
Electrons have two types of spins, clockwise and anti-clockwise. We denote clockwise spin as +1 state and anticlockwise as -1 state. If we have a system of two coherent electrons with opposite spins, then the total spin of system will be +1-1=zero. Now we take them apart and make a measurement on one of the electrons to measure the spin. If this electron has a clockwise spin, we would know for sure that the other electron has anticlockwise spin and vice versa. In fact, you know this faster than the speed of light!
In teleportation experiments physicists start with two atoms, A and C. Let’s say we wish to teleport information from atom A to atom C. We begin by introducing a third atom, B, which starts out being entangled with C, so B and C are coherent. Now atom A comes in contact with atom B. A scans B, so that the information content of atom A is transferred to atom B. A and B become entangled in the process. But since B and C were originally entangled, the information within A has now been transferred to atom C. In conclusion, atom A has now been teleported into atom C, that is, the information content of A is now identical to that of C. Notice that the information within atom A has been destroyed (so we don’t have two copies after the teleportation). This means that anyone being hypothetically teleported would die in the process. But the information content of his body would appear elsewhere. Notice also that atom A did not move to the position of atom C. On the contrary, it is the information within A (e.g., its spin) that has been transferred to C.
Can teleportation become a reality?
In 2004, physicists were able to teleport an atom from one place to another. In 2006 yet another advancement was made, for the first time involving a macroscopic object. Physicists at the Niels Bohr Institute in Copenhagen and the Max Planck Institute in Germany were able to entangle a light beam with a gas of cesium atoms. Then they encoded information contained inside laser pulses and were able to teleport this information to the cesium atoms over a distance of about half a meter. Sin conclusion teleportation exists at the atomic level, and we may eventually teleport complex and even organic molecules within a few decades. But teleporting a human being is a very complex task as the amount of information to be transferred from one place to another is tremendous. We might have to wait for centuries for this to happen even if it is allowed by the laws of physics.