In 2017, Chinese scientist were able to teleport a photon to a satellite in the Lower Earth
Orbit (LEO) of Earth. This news spread like a wildfire. Some even thought that teleportation
that was shown in ‘Star Trek’ was now possible. But it wasn’t the case. What they
achieved was in fact Quantum teleportation. What teleportation actually means is, dematerialising
a body from one place and materialising it at another. But what the scientist obtained
was Quantum teleportation, which means transferring Quantum information without any medium. In
the rest of the video we will tack about what is Quantum Teleportation and is it reality?
And up to what extent!
The idea of teleportation has been around in fiction and mythology for over a thousand
years. As discussed above Quantum teleportation is very different from the classical teleportation,
because only the quantum information is transferred. Quantum computers can make future networking
and communication hacking proof. In today’s world , we have successfully done this experiment
over a thousand times using photons. What exactly is Quantum teleportation? In Quantum
teleportation one object is not transferred from one place to other rather it’s quantum
information is teleported without any medium. The no cloning and no deleting theorem tells
us that quantum information neither be copied nor destroyed. But before that we need to
understand Quantum entanglement.
When a parent particle with zero spin decays and creates two particles. Spin is a conserved
quantity so it means that it cannot change and so, the daughter particles have opposite
spin.All fundamental particles in the universe have a property called spin .this does not
means that they actually spin, but they possess an angular momentum and an inclination in
space. We can measure this spin of particle. As a result we get two outcomes, either up
spin or down spin, both having a chance of 50-50% for outcome unless observed by an observer
. If one is up the other will be down, so tahrs the simplest example of quantum entanglement,
in which two particles have opposite spin and have a single wave function. Quantum engagement
allows for weird behaviour to be seen in the sizes as big as humans and more. The important
thing here is that both the particles have a single wave function that governs both of
the particles. These particles are then called entangled particles. The entanglement doesn’t
depends upon the particles being close to each other. As long as the two particles don’t
interact with anything we can separate them by feet, miles or even more distances and
the two particles are connected by a single wave function and have opposite spins. Under
certain circumstances, when two particles are created from a single particle, then the
two particles show a very unique link to each other . This link in known as quantum entanglement
.This idea seems a bit weird and called it ‘spooky action’, claiming on multiple
occasions that " God does not play dice " and it would also ruled out the theory
of relativity . However , Einstein ’s idea was dismissed and Bohr ’s idea still
remains a vital part of modern physics.
In quantum computing and teleporting qubits are used. They have the same function as the
bits we use today. The difference between qubits and bits is that, the value of bit
can be either 0 or 1, but the value of a qubit can be both 0 and 1 simultaneously! This is
the reason why quantum computers are way more faster than today’s computers.
To understand quantum teleportation lets consider two people Alex and Brandy. Alex is on earth
and Brandy is at ISS. Alex wants to transfer a photon C to brandy. For this process we
will need a pair of entangled particles. Let’s call each of the entangled particles as A
and B respectively. Now, Alex will keep a one of the particles, A, with him and the
other one B will be with Brandy. Since both of the particles affect each other no matter
whatever is the distance between them, after measuring, if one of the particles among them
will have and upstate then the other will have a downstate. For example, here particles
A and B are entangled and upon measuring if A has an upward spin, B will have a downward
spin. Since we are talking about quantum particles we cannot oversee the superposition principle.
According to the superposition principle, until the quantum particles aren’t measured
they remain in all of their possible states, also known as superposition state. Superposition
tells us that the Quantum particles can be in all their possible states unless observed
by anyone . But as we observe them , their wave functions crumple and only one of its
possible states is left with us . This means that Schrodinger’s cat is both dead and
alive until the box is opened .
Now moving on further I want you all to bear with me and listen closely to what I say.
Because understanding a very simple idea like this might be complex if you even miss a single
line! As soon as we observe the quantum particles, their wave function collapses and at last
we have only a single state. What I mean to say is that the particles remain in both upstate
and downstate simultaneously, but as soon as we observe them, their wave function collapses
and we get either an upstate or downstate. Until Alex docent measures both the photons
A and c, they remain in superposition state and when he measures both A and C individually
their wave function collapses and both the photons will go in a definite state due to
which we will not be able to teleport the photon x in space. So instead of measuring
them individually he measures their combined state and this measurement is called Bell
measurement. Now when he measures A and C in a combined state then the photon A interacts
with photon C. And since, photon A is already entangled with photon B so, the quantum information
of photon C is transferred to photo B through photon A. . This happens because the two particles
were already entangled , and any change in one particle would bring a change in the
other . However , the Brandy is still unaware that they have received the quantum information
of the particle C that is with Alex . Hence he still cannot make photon x through manipulation
. So we will need to contact the crew and inform them about our experiments through
any classical means of contact such as a phone call . We will use our qubits to send this
information to them. Now photon B which is with Brandy has the quantum information of
photon C and by manipulating it we can make a perfect clone of photon C and after this
the entanglement of photons A and B breaks, and B has the quantum states of C and we can
say that we teleported quantum C from earth to ISS.
But you might be thinking that Alex is still having both of the particles, so how can we
say that we teleported the photon C to space. According to the no cloning and deleting principle
which we mentioned earlier, as soon as Brandy manipulates the photon he has and extracts
the quantum state of photon C into it, the quantum state of the initial particle changes
into a different and unique state. C now changes and will have different properties, because
all of its initial properties have been transferred to Brandy. Hence , we have successfully teleported
our particle from California to ISS . Mission successful.
If we're lucky, using quantum teleportation, a single particle transferred could encode
enough information to tell you what you need to know about a single particle in a human.
But the situation could get more complicated very quicklyThis new advance could, potentially,
be incredibly useful or even revolutionary in constructing a quantum internet, which
would take computing power to a whole new level. But to transport a living human being
would require transporting a whole lot more than just the information encoding a person.
The information problem may, in fact, be a solvable one, if we can boil it down to "only"
requiring the same number of particles that make up a human being. But to construct an
entire human being from scratch — to say nothing about whether that human being at
the destination is even the same person as the one you began with at the source —
is a different problem entirely.
The phenomenon of quantum teleportation has been known for decades, and has been experimentally
confirmed under many different circumstances. However, its utility has been limited:
it only works on single particles; nothing material moves from place-to-place;
the photons exchanged need to travel from the source to the destination;
and they're limited by how far you can transport a photon without losing your signal.
Previously, that limit meant that a few kilometers was as far as you could go. Faithfully transferring
the information from an unknown quantum state to another location is a tremendous capability,
but it was too limited in range to, say, ever reach a spaceship. But that's why the new
advance is so spectacular. By establishing a channel link from Earth to a satellite,
most of the transport is through empty space, so there's virtually no loss-of-signal. This
achievement will bring a new era of quantum computing that will be a lot faster than the
faster supercomputers of today and we already have witnessed the first quantum computer!
So what do you all think about this achievement of scientists? Can we achieve teleportation
later on in science? Let us know about your views in the comment section. And don’t
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