Encryption, an ancient art. During the Roman War, a general passed on a battle report to the emperor, sending a secret code that the enemy could not understand - the Caesar Code, which was "three wrong places to go back," was thus born. The Yin symbols and Yin scripts commonly used in the military during the pre Qin period in China were a set of encryption methods. When the wheel of history moves into the Internet era, the complexity of cryptography is beyond Caesar's imagination, but it is more difficult to imagine that it may be a technological revolution that will subvert the existing public cryptosystem - quantum computing beyond classical computing methods, making confidential communication an amazing footnote to the old saying that "the only thing that is certain is uncertainty". Quantum communication, bidding farewell to the "eavesdropping storm". In 1994, the password of the Bank of England needed to be set to 155 bits to ensure that it could not be cracked. Why are large numbers difficult to decompose? For example, there is a huge LEGO building block castle in front of us, built from thousands of blocks of different colors. The combination of building blocks is so complex that no one can remember the position and color of each block at a glance. The process of decryption is like dismantling this huge castle, which is a daunting task. "In 1994, deciphering a 155 bit password required the most advanced computers at the time to continuously calculate for 20 years. With quantum computers, deciphering this length of password only took 0.3 seconds," said Long Guilu, Vice Dean of Research at the Beijing Institute of Quantum Information Science and Professor at Tsinghua University. Faced with the lightning fast password cracking of quantum computers, in order to achieve great success in secure communication, it is necessary to constantly upgrade. "Classical secure communication is like 'talking nonsense' that others cannot understand. Quantum secure communication is like saying 'whispers' that others cannot hear at all." Long Guilu explained that there are mainly two types of quantum secure communication: one is to use quantum states to generate keys, while quantum key distribution using classical communication to transmit encrypted information has the advantage of high transmission rates; Another approach is quantum direct communication where quantum states directly transmit information. In the event of eavesdropping, quantum states can self destruct to ensure information security. By utilizing the properties of quantum states, we can check and communicate simultaneously during information transmission. If there is a third party involved in covert eavesdropping in quantum communication, the dual convenience of communication will be detected: because covert eavesdropping can cause a change in the state of the quantum state, the receiver will take timely measures to protect the information if it detects abnormalities. That is to say, eavesdropping quantum communicators cannot hide eavesdropping behavior or steal any information. Quantum phones are not mythical landlines, BPs, mobile phones, smartphones... Over the past 30 years, we have all witnessed the rapid changes in communication methods. But people may not believe that quantum phones, which use quantum key distribution technology, have entered our lives. "With just an Android phone in hand and a quantum encrypted SIM card, you can make quantum calls," said Zhang Tao, Technical Director of Communication and Quantum Product Line at China Telecom Quantum Information Technology Group Co., Ltd. with ease. What is the difference between quantum phones and regular phones? Taking mobile phones as an example, the first one that can make quantum calls has modified the dialing component of ordinary phones, protecting the caller's privacy through quantum session keys