Did quantum computing just take a quantum leap? A two-qubit chip by UK researchers makes controlled quantum entanglements possible

A team led by Xiaogang Qiang from the Quantum Engineering Technology Labs at the University of Bristol in the UK, have designed a fully programmable silicon chip to control two-qubits of information simultaneously within a single integrated chip, taking us closer to the quantum computing era.

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The researchers invented a silicon chip which guides single particles of light (or photons) in optical tracks called waveguides to produce quantum-bits of information called “qubits”. This small device can be used to perform a wide range of quantum information experiments. It can also be used to demonstrate how completely functional quantum computers can be engineered from large-scale fabrication processes.

“We programmed the device to implement 98 different two-qubit unitary operations (with an average quantum process fidelity of 93.2 ± 4.5%), a two-qubit quantum approximate optimization algorithm, and efficient simulation of Szegedy directed quantum walks -- fosters further use of the linear-combination architecture with silicon photonics for future photonic quantum processors” write the researchers on the paper titled “Large-scale silicon quantum photonics implementing arbitrary two-qubit processing”.

The new design has solved one of the major problems faced during quantum computer development. With the current technology, it is possible to effectively carry out the operations requiring just a single qubit (a unit of information that is in a superposition of simultaneous “0” and “1”). But, by adding a second qubit, it enables quantum entanglement, which exacerbates the problem.

Qiang and colleagues have found a solution to this problem as their new quantum processor is capable of controlling two qubits. As mentioned in the paper “by using large-scale silicon photonic circuits to implement-- a linear combination of quantum operators scheme --we realize a fully programmable two-qubit quantum processor, enabling universal two-qubit quantum information processing in optics”. The paper also mentions that the quantum processor has been fabricated with mature CMOS-compatible processing and consists of more than 200 photonic components.

“It’s a very primitive processor because it only works on two qubits, which means there is still a long way before we can do useful computations with this technology,” says Lead author, Dr. Xiaogang Qiang.