Increasingly powerful microscopes have allowed us to see ever-smaller objects, down to the size of single atoms. Many of the operations of life, however, have evaded us, because the very act of looking destroys them. Now, a quantum microscope has proven it is possible to go beyond the bounds of what was thought possible when viewing living cells, and its makers hope to extend their reach much further.
To view the very small, we need to collect enough photons to build up a clear picture. For some tiny objects, this can be done by shining an intense amount of light on them. Professor Warwick Bowen of the University of Queensland told IFLScience some microscopes illuminate their targets with lasers a trillion times as intense as sunlight. It's not hard to guess the consequences when trying to study something as delicate as the innards of a cell.
Sometimes shining fainter light for longer, and building up a picture over time, resolves this – but that's no solution for a moving target. Moreover, Bowen explained; “Some forms of photodamage depend on the total illumination over time.” The use of fluorescent dyes or proteins is widespread, but there are fears they may change what happens in their absence.
Bowen's solution is to use more coherent light, taking out some of the noise, and therefore collecting a sharper image for the same intensity. The idea has been used before to improve gravitational wave detectors, but Bowen and colleagues are the first to make it work when applied to living things, or parts thereof.
In the journal Nature, Bowen has announced initial success, producing images 35 percent clearer than would be possible using established techniques. “Thirty-five percent is not nothing,” he told IFLScience, “But it is not massive either. It's unlikely anyone would build a microscope just for that.”
However, Bowen notes similar approaches in other fields have improved clarity 30-fold, and hopes to “squeeze” the light more effectively to do something similar. This would allow such a reduction in light intensity many delicate processes could survive, allowing us to watch them in real time. Getting there in a single leap might be too ambitious, but Bowen told IFLScience his next project is to try to make a microscope that requires 10 times less illumination than existing counterparts.
To make light more coherent even than lasers, Bowen and co-authors relied on quantum entanglement, the mind-bending way particles' fates can be bound together despite separation. "Entanglement is thought to lie at the heart of a quantum revolution,” Bowen said in a statement. "We've finally demonstrated that sensors that use it can supersede existing, non-quantum technology.”
There is a nice irony that quantum mechanics, famous for the principle that observing something changes it, can be used to get around the problem where our observations were changing the things we're studying to the point of destruction.
In addition to allowing us to investigate the processes within living things, Bowen hopes future generations of quantum microscopes will lead to better diagnostic technologies, helping us spot disease earlier and more accurately.