Quantum physic can guarantee that a message has not be intercepted before reaching its destination. Thanks to the laws of quantum physic, a particle of light – a photon – can be in two distinct states simultaneously, comparable to a coin thrown in the air, which is virtually both head and tail before reaching the ground. Like when the coin is grabbed, this superposition of states is destroyed as soon as it is read. This peculiar feature allow one to detect an evil eavesdropper when sending a message. However, this technique is so far limited to short distances. In order to extend the reach of these quantum communications, researchers from the University of Geneva (UNIGE), Switzerland, have demonstrated a novel protocol based on a crystal than can emit quantum light as well as store it for arbitrary long times. This work, to appear in Physical Review Letters, paves the way for a future quantum repeater.
Quantum superposition is one of the fascinating features of quantum physic. “In order to test the security of communication link, we can use particles of light, photons, onto which we encode quantum bits (analogous to the bit used in computing) ”, explains Cyril Laplane, a researcher in the Group of Applied Physics at UNIGE. He continues: “We then take advantage of the properties of quantum superposition, allowing the photon to be simultaneously in two states, to test the security of a communication link”. Indeed if the photon is intercepted and read, the superposition of states is lost, only one of the two states remains. Hence, the recipient can know if the message has been intercepted.
The need for quantum repeaters
Since this protocol relies on the use of single photons, there is an unneglectable chance of losing the particles when they propagate in traditional communication links such as the optical fiber. This problem becomes more and more critical with the distance. In order to communicate over long distances, one would need repeaters, which amplify and rebroadcast the signal. It is however impossible to use such procedure in quantum communication without destroying the superposition of states. Physicists need to build a quantum repeater able to store the dual character of the photon but also produce such state, a true challenge.
A crystal based solution
To build a quantum repeater, scientists have investigated a lot atomic gases, which usually require heavy experimental apparatus. “We are using a crystal capable of storing quantum state of light. It possesses the advantage of being relatively simple to use with potential for very long storage times”, clarifies Jean Etesse, a co-author of the paper. These crystals are able to absorb light and restore it later, without reading the information encoded on it. Furthermore, they can generate single photons and store them on demand. Another major asset is their potential for miniaturisation.
Since the crystal is the source and memory for quantum information, it simplifies the protocol for quantum repeaters and lays the foundation of a quantum internet. Physicists at UNIGE are already working on the creation of an elementary link of quantum communication using a repeater.
The Latest on: Long-distance quantum communication
- Supercomputing 18: Pioneer spirit at the “Quantum Communication Networks and Technologies” panel on November 27, 2018 at 8:31 am
Professor at the University of Calgary specializing in long-distance quantum communication among other topics Maria Spiropulu, Shang-Yi Ch’en Professor of Physics at Caltech and founder of Alliance fo... […]
- Manufacturing Bits: Nov. 13 on November 13, 2018 at 12:47 am
Traditional communication networks use public key cryptography. In contrast, quantum key distribution (QKD) uses quantum superposition states for unconditional security. Quantum networks have been dem... […]
- Scientists Worldwide Are Getting Serious About Quantum Internet on October 25, 2018 at 11:02 am
Quantum communication might allow you to perform calculations on the quantum cloud without the quantum computer knowing what computation it has done. Or you could entangle a qubit over a long distance ... […]
- New plans aim to deploy the first US quantum network from Boston to Washington, DC on October 25, 2018 at 7:41 am
but have risen to prominence in recent years as both a threat to some encryption and also the savior of future secure communications. Relying on photons and the laws of quantum physics to share encryp... […]
- Quantum network to test unhackable communications on October 24, 2018 at 9:19 pm
As the number of hacks and security breaches rapidly climbs, scientists say there may be a way to make a truly unhackable network by using the laws of quantum physics ... on developing improved device... […]
- Fiber-based quantum communication - Interference of photons using remote sources on October 23, 2018 at 4:34 am
Scientists are working on the totally bug-proof communication – the so-called quantum communication. Current approaches for long-distance signal transmission rely on repeaters which are based on a cru... […]
- Not Only China: Quantum Satellite Communication on the Rise in the Indo-Pacific on September 26, 2018 at 7:42 am
While quantum mechanics itself theoretically should be able to enable the safest communication, there are still challenges to establishing a long-distance network without any vulnerabilities in device... […]
- White House issues quantum computing strategy and hosts public-private summit on September 24, 2018 at 6:04 pm
Chinese researchers hold the record for long-distance quantum communications as well as for quantum entanglement of qubits. In a July op-ed, the chairs of the House and Senate science committees, Lama... […]
- New quantum repeater paves the way for long-distance big quantum data transmission on February 1, 2018 at 4:00 pm
Illustration of the new quantum repeater scheme for long-distance quantum communication ... bringing the implementation of long-distance big quantum data transmission closer to reality. The results ma... […]
- Applying the Principles of Quantum Entanglement to Secure Communication on January 18, 2018 at 7:04 am
The quantum technology used for data security comes with plenty of implementation challenges. The concept is still being researched and use of the technology requires costly infrastructure. In additio... […]
via Google News and Bing News