Information is usually stored in massive mediums, like books, text messages, DNA, and computers. But according to the American Physical Society, quantum information refers to data contained in tiny structures called qubits. Quantum information can increase the amount of information processed and communicated securely.
Quantum state sharing uses quantum entanglement to distribute a secret quantum state among multiple parties securely. The secret state can only be reconstructed if a majority of the players cooperate, and the protocol can also be used for quantum error correction.
Sharing Secret Information Possible Through an All-optical Quantum State Without Converting It Into Electrical Signals
Two Types of Systems of Quantum Information
Scientists use physics to transfer information between particles that are separated by space using teleportation. Through quantum information, it ensures secure communication and encrypted messages that can easily detect any attempt to intercept them.
There is also a drive to develop new more powerful computers that can solve complex problems much faster than today's machines. Examples of such problems include factoring large numbers that are used in data encryption, as well as sifting through enormous databases of information.
According to EurekAlert!, there are two types of systems in quantum information: discrete variable and continuous variable. The discrete variable system is good as it does not easily lose information. Meanwhile, continuous variable systems enable a high degree of precision in processing quantum states.
In an attempt to share quantum states between multiple locations, scientists have experimented with utilizing continuous variable systems. However, this process requires the use of electrical feedforward, a method that involves converting signals between electrical and optical forms. Unfortunately, this technique has its limitations, including decreased bandwidth for the sharing of quantum states.
A ray of hope for a more optimal solution lies in utilizing an all-optical quantum state sharing protocol that would allow quantum information to be shared using light, eliminating the need for signal conversion.
While this protocol has been proposed theoretically, its implementation has proven difficult due to difficulty in controlling noise naturally present in the amplified output state of select types of optical devices, and as such, has not yet been used practically.
Successful All-optical Quantum State Sharing
As researchers from East China Normal University wrote in their paper, titled "Deterministic All-optical Quantum State Sharing" published in Advanced Photonics, they successfully implemented the all-optical quantum state sharing using a low-noise amplifier which is based on a four-wave mixing process that substitutes electrical signals.
The new method allows sharing quantum states between two or more players so they can work together in retrieving the secret state while other players do not get anything. During the experiments, researchers found that the average fidelity of all structures was 0.74 ±0.03. More so, they were able to verify that the new system can be used at a certain bandwidth.
Professor Jietal Jing, the corresponding author of the study, said in the press release via EurekAlert! that their study aims to eliminate the bandwidth limit of quantum state sharing that is present in the continuous variable system. The findings show that an all-optical platform could be used for quantum state sharing, paving the way for constructing an all-optical broadband quantum network.
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