Quantum Communication by ISRO

What is Quantum Communication?

Quantum communication is a field of applied quantum physics closely related to quantum information processing and quantum teleportation. Its most interesting application is protecting information channels against eavesdropping by means of quantum cryptography. The most well known and developed application of quantum cryptography is quantum key distribution (QKD).

QKD describes the use of quantum mechanical effects to perform cryptographic tasks or to break cryptographic systems. The principle of operation of a QKD system is quite straightforward: two parties (Alice and Bob) use single photons that are randomly polarized to states representing ones and zeroes to transmit a series of random number sequences that are used as keys in cryptographic communications. Both stations are linked together with a quantum channel and a classical channel.

Alice generates a random stream of qubits that are sent over the quantum channel. Upon reception of the stream Bob and Alice — using the classical channel — perform classical operations to check if an eavesdropper has tried to extract information on the qubits stream. The presence of an eavesdropper is revealed by the imperfect correlation between the two lists of bits obtained after the transmission of qubits between the emitter and the receiver. One important component of virtually all proper encryption schemes is true randomness which can elegantly be generated by means of quantum optics.

ISRO’s Achivement:

Quantum Experiments Using Satellite Technology (QuEST) Project:

QuEST launched in 2017, is being implemented by Raman Research Institute or RRI in collaboration with ISRO.It is carried out by Raman Research Institute’s quantum information and computing or QuIC lab, is India’s first ever project on satellite based long distance quantum communications. 

The results of the project were seen in february 2021 when a team of researchers led by Professor Urbasi Sinha demonstrated a communication between two structures 50 metres apart. The use of quantum key technology was done in this experiment. 

ISRO has demonstrated the same thing now. It demonstrated free space quantum communication over 300 metres. 

On 19th March, ISRO demonstrated the technology enabling secure communication between buildings located in SAC campus in Ahmedabad. These buildings were 300 metres apart. The testing was carried out at night to avoid interference due to direct sunlight. 

As per ISRO a number of key technologies were developed indigenously to accomplish the success of this experiment. It included-

1. Indigenously developed NAVIC receiver for time synchronization between the transmitter and receiver modules
2. Gimbal mechanism systems instead of bulky large-aperture telescopes for optical alignment
3. As per the statement released by ISRO, “this is a major milestone achievement for unconditionally secured satellite data communication using quantum technologies.”

Quantum Key distribution:

The Quantum Key Distribution (QKD) technology is the technology behind Quantum Communication technology ensuring unconditional data security by using it’s principles of quantum mechanics, which may be impossible using conventional encryption systems.

These conventional crypto-systems that are used for data-encryption rely on the complexity of mathematical algorithms. The laws of Physics ensure the security offered by quantum communication. Thus, quantum cryptography is being seen as the ‘future-proof’. The reason for such consideration can be no expectations from any future advancements in the computational power breaking the quantum-cryptosystem.

Advantages

• It ensures unconditional data security by virtue of the principles of quantum mechanics, which is not possible with the conventional encryption systems.
• Quantum Cryptography is based on the laws of Quantum Physics will be easier than conventional cryptosystems used for data-encryption rely on the complexity of mathematical algorithms.
• It is considered ‘Future-proof’ since no future advancements in computational power can break quantum-cryptosystems.
• The technology can come in handy for several sectors that include digital money transactions, defence, etc.
• MeitY has partnered with Amazon Web Services (AWS) to set up a Quantum Computing Applications Lab in the Country. The lab will be the World’s 1st Quantum Computing Applications Lab to support a National Government’s Mission.

Challenges of QKD

• For now, it is currently difficult to implement an ideal infrastructure for QKD. QKD is perfectly secure in theory, but in practice, imperfections in tools like single photon detectors create many security vulnerabilities.

Source: ISRO

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