Quantum Connectivity: A Trump Card for Secure Internet Networking

A team of Chinese researchers has been able to link quantum memories extending up to 22 km of optic fiber using two-photon interference techniques and to 50 km using single-photon interference. Thus beating the previous record by more than 40 times over. This achievement comes from collaboration by scientists at University of Science and Technology of China (USTC; Hefei, China), the Jinan Institute of Quantum Technology (Jinan, China), and the Shanghai Institute of Microsystem and Information Technology (SIMIT) at the Chinese Academy of Sciences (Shanghai, China). Their work has brought us closer to a super-fast, super-secure quantum internet that shall dominate network connectivity in the future. It also exhibits a shorter entanglement creation time (150 and 0.65 seconds, respectively, compared to 1300 seconds) with better quantum link efficiency.

Quantum entanglement is a quantum mechanical phenomenon where two particles when forming a link, no matter how far the particles are, when one particle spins, another particle will spin at the same time. That is no fundamental state properties like momentum, position, or polarization can happen randomly. The phenomenon of quantum entanglement shows that particles can break through the boundary of space-time and transmit information faster than the speed of light. Einstein mocked this concept calling this phenomenon "spooky action at a distance".

A quantum internet relies on this entanglement to send information from one place to another. Unlike traditional computers that can either exist at 0 or 1, quantum bits or qubits can superpose a 0 and a 1 in the same unit. Thus it can send hack-proof messages, improve the accuracy of GPS, and enable cloud-based quantum computing. In case hackers mess with communication, they would spoil the entanglement, thus revealing their presence.

The experiment was simple. In their published article on Nature, the team mentioned that they used difference frequency generation (DFG) in a lithium niobate waveguide to shift the near-infrared photons to the telecommunications O band (centered at 1342 nm) to enable a low-loss transmission in standard optical fibers. This was to prevent the absorption of the photons in the optical fiber.

The team used two identical storage units for quantum memory which were rubidium atoms chilled down to a low energy state. Then using a laser they generated a photon whose polarization is entangled with the cloud's internal state. And send them to a third station which was 11km away, where the photons interacted in a way similar to original entanglement.

While distance is also another major hurdle in quantum communication, Harvard and Massachusetts Institute of Technology (MIT) researchers found a way to send the signal over a large distance. Enter quantum repeaters. These devices create a network of entangled particles through which a message can be transmitted. They shall catch and process qubits information to correct errors and store them long enough (milliseconds) for the rest of the network to be ready. The team experimented on silicon-vacancy color centers in diamonds due to the ability to absorb and radiating light, which gives the diamond its' brilliant colors.

Although we are yet to witness the future of data transmission, quantum internet can modify a lot of things. From being our key to data security to tasks that demand higher degrees of coordination, communication, and synchronization. The next ubiquitous challenge will be scaling them down to fit into our daily carry on devices and gadgets.