Chinese scientists demonstrated the first two-dimensional quantum walks of single photons in real spatial space, which may provide a powerful platform to boost analog quantum computing.

They reported in a paper published on Friday in the journal Science Advances a three-dimensional photonic chip with a scale up to 49-multiply-49 nodes, by using a technique called femtosecond direct writing.

Jin Xianmin, a quantum communication researcher with Shanghai Jiaotong University, who led the study, told Xinhua, it is the largest-scaled chip reported so far that allows for the realization of this two-dimensional quantum walk in real spatial space, and potential exploration for many new quantum computing tasks.

Jin and his colleague showed that the dimension and scale of quantum system could be employed as new resources for boosting the quantum computing power.

The researchers said, universal quantum computers came under the spotlight since last year, as IBM, Google, Intel and the rivals constantly competed to announce their new records on the achieved number of qubits.

However, universal quantum computers are far from being feasible before error correction and full connections between the increasing numbers of qubits could be realized.

In contrast, analog quantum computers, or quantum simulators, can be built in a straightforward way to solve practical problems directly without error correction, and potentially be able to beat the computational power of classical computers in the near future.

Quantum walk in a two-dimensional array is a strikingly powerful and straightforward approach to analog quantum computing. It maps certain computing tasks into the coupling matrix of the quantum paths, and provides efficient solutions to those even classically intractable problems.

Prominent quantum advantages will be promptly achievable as long as the scale of quantum systems goes above a considerably large level.

During the past two decades, a traditional and challenging method has been through increasing the photon number, which suffers from probabilistic generation of single photons and multiplicative loss, according to the researchers.

This ingenuous alternative way from increasing the external physics dimension and complexity of the quantum evolution system may accelerate future analog quantum computing, said Jin.

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