Quantum communication is an important application of quantum information which is impossible to be deciphered or intercepted. However, its high dependence of surroundings makes efficient quantum communication a challenge in the face of noises.
In a study published in Physical Review Letters, the group of Prof. LI Chuanfeng and Prof. LIU Biheng from academician GUO Guangcan's team at University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, and international collaborators, achieved high-efficient, high-dimensional quantum communication in an environment of high noise.
Basically, it’s the uncertain property that realizes quantum communication, namely, a particle’s bizarre ability to store the bit 0 or 1, or even both simultaneously. Although theoretical findings back that high-dimensional quantum systems exceed low-dimensional systems at channel captivity and noise resistance, experimentally there’s still a long way to go before getting close to efficient high-dimensional quantum communication.
Prof. LI Chuanfeng and Prof. LIU Biheng's team has devoted to experiments regarding quantum communication network for several years and has made a series of progress. Based on their previous research, they set up a quantum measurement for high-dimensional quantum communication.
In this study, the researchers succeeded in producing a bi-photonic multi-dimensional path-wise entanglement. They designed and tested a multioutcome measuring device, which could separately probe the two photons with up to eight outputs.
In order to study how noise affects the system, the researchers illuminated the detectors with LED lights as ambient noise, which facilitated noise modulation by simply adjusting the LED’s brightness.
They found that, under minor noise, high-dimensional, full-space coding produced higher efficiency, and four- or eight-dimensional entanglement ensures a key rate higher than one bit per photon pair even after error correction and privacy amplification, exceeding the limitations of the two-dimensional systems.
Besides, the researchers found that as the noise grew in density, high-dimensional subspace coding turned out to be more resistant to noise, ensuring the efficiency of quantum communication in the face of noises.
The findings of this study verified the superiority of high-dimensional quantum communication, and provided accessible ways of efficient communication under noises of varied intensity.
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