China adds a quantum computer to high-performance computing arsenal

The country has developed a quantum computer based on multi-photon entanglement.

China Forbidden City
Credit: Michael Kan

China already has the world's fastest supercomputer and has now built a crude quantum computer that could outpace today's PCs and servers.

Quantum computers have already been built by companies like IBM and D-Wave, but Chinese researchers have taken a different approach. They are introducing quantum computing using multiple photons, which could provide a superior way to calculate compared to today's computers. 

The Chinese quantum computing architecture allows for five-photon sampling and entanglement. It's an improvement over previous experiments involving single-photon sourcing, up to 24,000 times faster, the researchers claimed.

The Chinese researchers have built components required for Boson sampling, which has been theorized for a long time and is considered an easy way to build a quantum computer. The architecture built by the Chinese can include a large number of photons, which increases the speed and scale of computing.

China is strengthening its technology arsenal in an effort to be self-sufficient. China's homegrown chip powers TaihuLight, the world's fastest computer.

In 2014, China said it would spend US$150 billion on semiconductor development so that PCs and mobile devices would convert to homegrown chips. Afraid that low-cost Chinese chips will flood the market, the U.S. earlier this year accused China of rigging the semiconductor market to its advantage.

It's not clear yet if a quantum computer is on China's national agenda. But China's rapid progress of technology is worrying countries like the U.S. A superfast quantum computer could enhance the country's progress in areas like weapons development, in which high-performance computers are key.

But there's a long way to go before China builds its first full-fledged quantum computer. The prototype quantum computer is good for specific uses but is not designed to be a universal quantum computer that can run any task.

The research behind quantum computers is gaining steam as PCs and servers reach their limit. It's becoming difficult to shrink chips to smaller geometries, which could upset the cycle of reducing costs of computers while boosting speeds.

If they deliver on their promise, quantum computers will drive computing into the future. They are fundamentally different from computers used today.

Bits on today’s computers are stored as ones or zeros, while quantum computers rely on qubits, also called quantum bits. Qubits can achieve various states, including holding a one and zero simultaneously, and those states can multiply.

The parallelism allows qubits to do more calculations simultaneously. However, qubits are considered fragile and highly unstable, and can easily breakdown during entanglement, a technical term for when qubits interact. A breakdown could bring instability to a computing process.

The Chinese quantum computer has a photon device based on quantum dots, demultiplexers, photonic circuits, and detectors.

There are multiple ways to build a quantum computer, including via superconducting qubits, which is the building block for D-Wave Systems' systems. Like the Chinese system, D-Wave's quantum annealing method is another easy way to build a quantum computer but is not considered ideal for a universal quantum computer.

IBM already has a 5-qubit quantum computer that is available via the cloud. It is now chasing a universal quantum computer using superconducting qubits but has a different gating model to stabilize systems. Microsoft is trying to chase a new quantum computer based on a new topography and a yet-undiscovered particle called non-abelian anyons.

In a bid to build computers of the future, China has also built a neuromorphic chip called Darwin.

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