What is Quantum internet?
A
traditional computer uses charge accumulated between two parallel plates to represent
either 0 or 1, which are called bits. In a quantum computer, 0 and 1 can be represented
based on the state of the electrons or photons. For example, the spin of
electrons can be used to notate 0 and 1 – spin up and spin down. The
polarization of a photon can also be used as horizontal polarization to
represent 0 and vertical polarization to 1. These are called qubits, which is
derived from Quantum Bits.
Just like a
network of traditional computers used for data access across the globe is called Internet, a network of quantum computers used for the same is called Quantum internet.
In
traditional computing, a bit would have only one state – either 0 or 1. But in
quantum computing, a qubit can in both 0 and 1 states simultaneously. The current
status of quantum internet did not cross the lab level yet. DARPA Quantum
network is the world’s first quantum network operating 10 optical nodes across Boston,
Cambridge and Massachusetts.
Recently, a
team of scientists successfully transmitted quantum memory over more than 50
km. In comparison with the modern metrics, this is not a great range. But in
comparison with the previous metrics of quantum memory transmission metrics,
this is more than 40 times that of the capacity.
If two or
more qubits are put together, they become entangled to each other. This
entanglement affects the qubits in a quiet strange manner. When two or more
particles are entangled together, any action performed on one of the particles instantaneously
affects the remaining particles, irrespective of the distance between them. Albert
Einstein named this phenomenon as “spooky action at a distance”.
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| Quantum Communication |
Jian-Wei
Pan is one of the research scientists who is working on building the quantum internet.
In 2017, Pan along with his team built a Quantum Secure Communication Beijing-Shanghai
Backbone Network with the help of an Earth-orbiting satellite relay named Micius.
Pan has also mentioned that they have successfully demonstrated the
entanglement of various particles though empty space. Here is the entire interview
of Pan back from March 2019.
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| Quantum leaps - China's Earth-orbiting satellite Micius Image source - Google |
Data rates in quantum networks:
Quantum networking
takes the advantage of this spooky action at a distance phenomenon in order to transmit
data. Hence in comparison with the data rate of traditional internet, the data rate
of quantum networks is several folds higher.
Security in quantum networks:
The data in
quantum networks is stored as a superposition of 0 and 1, and the link might be
established in any shape. So, communication between two quantum computers
cannot be intercepted. Even if the data is intercepted, the state of the particles
is disturbed. This capability of quantum leads to another part of security – communication
between two quantum computers cannot be intercepted without letting the
computer know who intercepted.
Limitation of quantum networks:
Though
quantum networks or quantum internet comes with relatively high advantages, there
are several limitations this technology is currently facing.
In
practice, entanglement of particles is not an easy task. Even a slight change
in temperature or a slightest vibration in the medium can result in disturbance
of the state of the particles. This ultimately results in data loss.
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| Jian-Wei Pan in lab building the quantum internet Image source - Google |
It is expected that it takes a decade more, in order to build a successful quantum network with all these challenges addressed.
The near-term target is to make telecommunication more secure. The quantum internet of the future might be completely different from what we imagine now.
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