PCI

Quantum Internet

The world is now witnessing the birth of a Chinese quantum internet that will revolutionize society by allowing non-hackable transfers of data, and optimizing machine learning for the ‘internet of things’, and eventually leading to instantaneous communication.

Quantum computing allows evaluating multiple possibilities at once, and the performing of complex calculations not possible on normal computers. Quantum computers aren’t just about doing things faster or more efficiently, they’ll let us do things that we couldn’t even have dreamed of without them. Things that even the best supercomputer just isn’t capable of.

If you ask a normal computer to figure its way out of a maze, it will try every single branch in turn, ruling them all out individually until it finds the right one. A quantum computer can go down every path of the maze at once. It can hold uncertainty in its head.

The Chinese scientists teleported quantum information 1,400km to two satellites, then back to earth via receiver stations, which is a first step in creating a global-scale quantum internet.

Jiuzhang, China’s photonic quantum computer, harnesses particles of light, called photons. Named after an ancient Chinese mathematical text, this quantum computer can perform a calculation in 3 minutes that would take over 500 million years on the world’s fastest non-quantum, classical computer.

This computer gained “quantum advantage” over the most advanced classic supercomputer through the use of photons to solve calculations, instead of the classical use of electrical binary signals in microprocessors.

Therefore, China is now playing the leading role in the application of quantum communications. This technology has advanced applications for the Chinese military, its finance sector, and its overall communications.

Applications of the new technology would transform “the field of quantum chemistry and optimization, which can be helpful in designing new materials and machine learning”.

Jiuzhan has an advantage over its competitors, such as Google’s Sycamore, as it uses photons that are naturally compatible with the internet, because obviously flying photons are the fastest and only sensible way to transfer information over long distances. Quantum computation and quantum communication using photons share a lot of techniques in common.

Sycamore is based on tiny quantum bits made of superconducting materials, which conduct energy without resistance, whereas Jiuzhang consists of a complex array of optical devices that shuttle photons around. Those devices include light sources, hundreds of beam splitters, dozens of mirrors and 100 photon detectors. See image below.

Sycamore relies on super-cold, superconducting metal, whereas the Chinese alternative can operate at room temperature.

One promising application for quantum computers is their ability to solve machine-learning optimization problems and quickly read huge data sets. This speeding up of machine-learning algorithms will allow much more advanced autonomous devices. The development of the internet of things will see vast scales of data gathered every second by devices, sensors and machines.

Quantum computers, the ideal information-processing systems

“Quantum supremacy” is based on such devices outperforming classical supercomputers. Building quantum computer machines is a race between nature and humans, not between countries, where the whole international community should closely collaborate.

The move is a key part of the blueprint to make China technologically self-reliant and a global leader in scientific research and development.

A new institute has been created: the Chinese National Laboratory for Quantum Information Sciences. The institute was behind the creation of the integrated quantum network, consisting of two satellites and thousands of kilometers of optical fiber cables linking key government facilities, power grids, military posts, and banks between Beijing and Shanghai. The whole system is claimed to be immune from disruptive cyber-attacks.

Quantum computing can utilize two fundamental properties of quantum mechanics: superposition and entanglement. Superposition means the information held in ‘qubits’ can exist in two different states simultaneously. This could allow vast amounts of information to be stored in sections of code.

The infinite variables allow the quantum computer vast amounts of processing power, because each qubit can perform multiple calculations at once. Superposition also greatly increases the speed by which a quantum computer can solve certain problems that would take classical computers millions of years.

For instance, the computational advantage of China’s quantum computer can solve mathematical problems in seconds that the world’s fastest conventional computer, Japan’s Fugaku, would take an estimated 600 million years to solve.

Entanglement is another advantage of the quantum world, and is one of the strangest phenomena of quantum mechanics, in which subatomic particles that are nearby each other influence each other in some way, such as the direction they spin in.

However, the strange effects of entanglement mean that when these two particles are separated, no matter at how vast a distance, if one is changed, the other goes through the same changes at exactly the same time, meaning these two particles are intimately and forever connected. The principle of entanglement could be used by quantum devices for the exponentially faster communication of information.

Jiuzhang process

Employing a process called boson sampling, Jiuzhang generates a distribution of numbers that is exceedingly difficult for a classical computer to replicate.

Here’s how it works: Photons are first sent into a network of channels. There, each photon encounters a series of beam splitters, each of which sends the photon down two paths simultaneously, in what is called a quantum superposition. Paths also merge together, and the repeated splitting and merging causes the photons to interfere with one another according to quantum physics rules.

Finally, the number of photons in each of the network’s output channels is measured at the end. When repeated many times, this process produces a distribution of numbers based on how many photons were found in each output.

If operated with large numbers of photons and many channels, the quantum computer will produce a distribution of numbers that is too complex for a classical computer to calculate. In the new experiment, up to 76 photons traversed a network of 100 channels.

The result will boost the profile of photonic quantum computers, which haven’t always received as much attention as other technologies,

Jiuzhang’s current limitation is that it can perform only a single type of task, namely, boson sampling, although it can process info 10B times faster than Google's, the Sycamore, which could be programmed to execute a variety of algorithms. The Xanadu photonic quantum computer is also programmable. China's latest is the 62-qubit Zu Chongzhi processor.