Scientists conjure up tiny, reconfigurable quantum chip

Researchers at the University of Bristol think they’ve cracked a way to get one step closer to quantum computing, figuring out a method to run photon entanglement onto a single, small silica chip. 

Entanglement is a key process in quantum computing. It’s the connection between two distant particles, which the researchers claim they have managed to tame – learning how to generate, manipulate and measure the process on the chip.

Along with that, the researchers have used the chip to measure mixture, which is an unwanted environmental effect that they say can now be controlled and used to characterise quantum circuits.

Researchers have, until now, been scratching their heads about controlling entanglement and mixture, puzzles in building quantum computers.

Entanglement and mixture needs to be controlled on a chip if anyone’s going to scalably duplicate miniature circuits. The team says its new device makes that a reality, and in turn is a major step on the road towards optical quantum computing.

The team’s chip is able to perform complex experiments which, normally, could only run on an optical bench the “size of a large dining table”. This chip is about the size of an ant’s dining table – 70mm x 3mm. 

In it is a network of tiny channels, the team says, which can manipulate and interact single photons. It has eight configurable electrodes embedded in the circuit, meaning photon pairs can be manipulated and entangled. That, in turn, means the chip produces any possible entangled state of two photons or a mixed state of one photon.

Key to the study is the fact it’s reconfigurable. If a quantum computer can only perform one specific task it’s not too helpful. Lead author Peter Shadbolt said what is preferred is a reconfigurable device that can run different tasks, like desktop PCs, which is exactly what he claims to have created. The device is roughly ten times more complex, the team says, than previous experiments looking at the technology – which is of note because difficult experiments can be performed in an easy way on the reconfigurable chip.

Next is scaling up the complexity of the device. The researchers believe it’s a “building block” for future quantum computing and it has been described by a top boffin at Imperial College London, Dr Terry Rudolph, as “an awesome achievement.”