China scientists put direct quantum communications tech to test in space flight

A laser module and a phase encoding device, developed at the Beijing Academy of Quantum Information Sciences, were on board a Yuanxingzhe-1 rocket that reached 2.5km (1.55 miles) during a two-minute vertical flight testing its reusability last Thursday.

“The launch mainly tested the robustness of the modules against various environmental stresses encountered during rocket ascent, such as vibration and radiation,” the academy said on its official social media account on Wednesday.

The test marked a key step in China’s transition from experimental validation to the construction of a fully integrated space-air-ground quantum secure direct communication (QSDC) network, the academy added.

First proposed by Chinese physicists in 2002, QSDC is considered complementary to another form of quantum secure communication, known as quantum key distribution (QKD).

While QKD involves generating encryption keys for use over conventional communication channels, QSDC skips the key-sharing step and sends the actual message directly through a quantum channel.

This makes the system more efficient and, in principle, more secure, which has led to some experts referring to QSDC as the “ultimate form” of secure communication.

South China Morning Post