Researchers at the University of Bristol are using single photons and quantum technology to look directly at complex molecules.

Opening the Bristol Quantum Information Technology workshop, Prof John Rarity (above) pointed to new imaging technology using single photons that can be used on fragile samples that would be destroyed by other techniques such as electron microscopes.

“This is our biggest ever conference with over 200 people from many areas, including industry, computing, simulation, metrology and communications,” he said.

The imaging system uses a non-linear crystal that can generate an 800nm correlated pair of photons – one collects data through a sample, the other collects the shot noise from the system, and then two are subtracted in a commercial CCD camera sensor.

“It’s quite hard to do but we have specialised in Bristol in single mode – we built a system that collects photons with an efficiency of 86% into a single mode fibre and we can put both of them onto the same CCD and do the subtraction,” sais Rarity

“We are now doing imaging by scanning the camera with almost twice the precision of the shot noise limit. We have a 1-micron resolution at the moment and we have tested it with a QET labs logo that was too small for electron microscopes,” he said, “We are targeting a 3dB noise reduction in scanned imaging – we have achieved 2dB so far.”

“Now we want to use this is more real-world scenarios and look at photosensitive samples that might be bleached by the lights, and trying the original idea of a multimode source and make the number of modes to give a reasonable image quality. We are looking at sensitive samples that would otherwise be destroyed by electrons down to around half a micron, 500nm, the edge resolution is 250 to 300nm.

Researchers at looking at quantum computing, cybersecurity and many other areas at the BQIT workshop are www.bristol.ac.uk/physics/research/quantum/conferences/bqit-workshop/

Nick Flaherty