Explanation:

Information can be transmitted using either the principles of classical physics and quantum physics. The two follow different principles.
For e.g. information obeying the laws of classical physics, such as a A4 sheet with text or a telephone signal, can be easily hacked in because it is so easy to copy that data by a third-party receiver.
But, quantum data follows the no-cloning theorem, i.e. the data cannot be exactly copied, and also the data cannot be fully destroyed.
The Quantum communication system is based on quantum cryptography. To break down the terms; cryptography concerns secure transmission; and Quantum uses the principles of quantum physics to transmit data.
It has been called a potential game-changer during a time when cybersecurity and privacy have become a constant concern for individuals, companies and governments.
The newly launched Beijing-Shanghai quantum link connects Beijing to Jinan to Hefei to Shanghai, a distance of more than 1,200 miles. Several major Chinese banks are already using the link to transfer their most sensitive data.