Quantum Teleportation Revolutionizing Information Transfer
Ever wish that those sci-fi movie scenes of magically transporting objects or yourself from one place to another would come true?
Teleportation does sound cool, doesn’t it? Moving around without any effort or work required. Yet, there is a possibility that teleportation might not merely be a topic of discussion for science fiction. Though we may not be able to teleport objects on a larger scale we have found a way to start small through quantum teleportation.
Before diving into teleportation, let’s classify a few terms. To understand the fundamentals of quantum teleportation and quantum computers we first need to know a bit about quantum mechanics. This is a field in quantum physics which describes the behaviour of atoms and subatomic particles on a smaller scale with quantum phenomenon. Once we decrease the size of an object or piece of information to as small as an atom, we are dealing with a whole new level of science.
Quantum teleportation applies the laws of quantum mechanics to the transfer of quantum information from one location to another with the help of a form of classical communication. Essentially it all starts with a bit which contains information. A classical bit can have a state of 1 or 0. Whereas through a phenomenon known as superposition, a quantum bit (qubit) can have a state of 1 and 0 at the same time. A quantum bit is the basic unit used to contain information in a quantum computer. Another theory in this field is quantum entanglement, which allows two qubits to be connected even as they are separated by a large distance. This is what Einstein described as “spooky action at a distance.”
Now quantum teleportation isn’t quite as we imagine teleportation to be in terms of moving objects over distances without any required work or effort. Instead during quantum teleportation, the information is transferred from one particle to another rather than the bit being transported. When the quantum state of a particle is transported from one particle to another, the state in the first particle is erased.
Since qubits can be in the position of both 0’s and 1’s it allows for this transfer of information. Essentially this means that quantum teleportation can occur when the state of the first particle is unknown. This is extremely helpful because observing the state could cause it to collapse and alter. For example, let’s say you wanted to send information from particle A to B. Since A is in a superposition of 1 and 0 we can describe its state as a coin on its edge that is both heads and tails resting on a table. Observing the state of the particle would be like smashing your hand onto the table causing the coin to collapse onto either heads or tails. This phenomenon can be described as decoherence. In essence it is when the particle collapses on to a state and loses its superposition once it is observed.
In order to transmit the information, the states use quantum entanglement. Therefore, they act as one quantum item, mathematically the quantum properties of this single object can be described through a wave function.
How exactly does this work though?
At first, we need to set up a quantum transmission channel by entangling a pair of particles. This way the particles are correlated. Particle A is with the sender who we can identify as Alice and B is given to the receiver who we call Bob. Since the particles are entangled whatever we do to one will affect the other.
Alice also has another particle C which she does not know the state of but wants to transport to particle B. In order to teleport the particle, Alice does a Bell measurement on particles A and C. This measurement would help Bob find the original state of the teleported particle through the quantum channel. This will not tell us the state of particle C but because of the entanglement that particles A and B share, particle B can be turned into the state that particle C originally had if Bob is able to apply the correct operation. Yet once Alice applies the Bell measurement on C, the state of C is erased.
Yet how does Bob know what measurement to apply?
We can find that from the result of the Bell measurement Alice did. Through a form of classical communication, such as email or phone, Alice needs to share the result of her measurement to Bob. This way Bob knows what to do to turn particle B to a state that is similar to that of particle C.
We can transport information from one state to another, but what does this exactly mean?
Well, this changes how quantum bits are sent, allowing faster processors as well as wide scale technologies for encryption. In terms of encryption, let’s take our credit cards as an example. They use a public key for our credit card information but encryption technologies make it extremely difficult to factor large prime numbers. Yet this can easily be solved with the help of quantum computers, where these large numbers can be factored.
This is also beneficial in quantum cryptography where messages in quantum states are impossible to detect. In order for this to happen it is important that the particle that we are teleporting is not copied. This is not allowed especially because of a law in quantum mechanics known as no-cloning where it’s not possible to duplicate an unknown quantum state. Not only does this help with quantum cryptography but a downside is that no-cloning makes quantum error correction difficult in quantum computers. This is where quantum information is protected from decoherence and other sources of quantum noise in quantum computers.
The mind-blowing fact about quantum teleportation is how information is sent immediately, essentially faster than light because the two particles are entangled. Yet, that would go against a fundamental law of the universe that light is the speed limit. In fact, quantum teleportation does not go faster than light even though it might seem like it does. This is because we still need a classical form of communication involved in the process, which is bound by the speed of light.
Quantum Teleportation — so what?
The breakthrough in quantum teleportation will allow for faster processing quantum computers where information is transported at higher rates. The transfer of information between qubits will advance the use of quantum information. This will not only allow for more efficient processors but also add to breakthroughs in technology in terms of encryption and cryptography.
Well we might not be able to transfer an object from one place to another without any effort. Yet, we can transport information from one location to another. Now that’s a step closer to living like a science fiction movie.
