Toshiba (one of the heavyweights in the world of technology) announced this week that it has successfully transmitted quantum information over fiber optics 600 km long.
Company researchers set a new distance record and heralded a new future for giant quantum networks They could send information securely between cities and even countries. These scientists have shown that they can transmit quantum bits over hundreds of kilometers of optical fiber without encoding the fragile quantum data encoded in the particles.
According to them, the reason for its success is due to a new technology that stabilizes environmental fluctuations that occur in the fiber. This discovery could go a long way toward creating a next-generation quantum Internet, which scientists hope will one day span global distances.
To cope with unstable conditions within optical fibers, Toshiba researchers They have developed a new technique called 'dual band stabilization'. The new technique sends two optical reference signals at different wavelengths, minimizing jitter in long fibers.
The first wavelength is used to cancel out fast fluctuations, while the second, which has the same wavelength as the optical qubits, allows phase adjustment.
Los investigadores found that it was possible to keep the optical phase of a constant quantum signal at a fraction of a wavelength, with an accuracy of a few tens of nanometers, even after propagating through hundreds of kilometers of fiber. If these fluctuations are not compensated for in real time, the fiber expands and contracts according to temperature variations, which encodes the quantum information.
A of the first applications of this technique in the real world will be the distribution of quantum keys (QKD) over long distances. According to a press release issued by Toshiba last week, commercial QKD systems are currently limited to around 100-200km of fiber optics. The company's research team has already used its technology to test QKD at a longer distance.
The protocol relies on quantum networks to create secure keys that cannot be hacked, which means that users can securely exchange confidential information, such as bank statements or medical records, through an untrusted communication channel, such as the Internet.
“In recent years, QKD has been used to protect metro networks. This latest advancement extends the maximum reach of a quantum link, so that cities can be connected across countries and continents, without using reliable intermediate nodes. Implemented with QKD via satellite, it will allow us to build a global secure quantum communications network, ”said Andrew Shields, Director of Quantum Technologies at Toshiba Europe.
During a communication, the QKD works by having one of the two parties encrypt data by encoding the cryptographic key in qubits and sending these qubits to the other party through a quantum network. However, due to the laws of quantum mechanics, it is impossible for a spy to intercept qubits without leaving a visible eavesdrop for users, who can then take steps to protect the information, according to the Toshiba team.
Unlike classical cryptography, QKD is not based on the mathematical complexity of security key resolution, but is based on the laws of physics. This means that even the most powerful computers could not hack qubit-based keys. So it's easy to see why the idea is attracting the interest of gamers from all walks of life, from financial institutions to intelligence agencies.
Toshiba's research has been partially funded by the European Union, showing great interest in the development of quantum communications. At the same time, China's latest five-year plan also places special emphasis on quantum networks, while the United States recently published a master plan that sets out a step-by-step guide to establishing a global quantum Internet.
The quantum internet is expected to enable uses that are impossible with today's web applications And this goes from the generation of virtually tamper-proof communications to the creation of groups of interconnected quantum devices that, together, could exceed the computing power of conventional devices.