A team of researchers in Germany and Australia recently used a new microscopy technique to image biological structures at the nano-scale in a previously unmanageable solution without destroying the living cell. The technology, which uses laser light many millions of times brighter than the sun, has implications for biomedical technology and navigation technology.
The quantum optical microscope is an example of how the strange principle of quantum entanglement can contain applications in the real world. Two particles are entangled when their properties are interdependent – by measuring one of them you can also know the properties of the other.
The sensor in the team microscope, described in a paper published today, science hangs on quantum lights – tangled pairs of photons – to see better-resolved structures without damaging them.
“The key question we answer is about quantum light can allow performance in microscopes that go beyond the limits of what is possible using conventional techniques, ”said Warwick Bowen, a quantum physicist at the University of Queensland in Australia and co-author of the new study, in an email. Bowen’s team found out that it actually can. “We are demonstrating [that] for the first time showing that quantum correlations can allow performance (enhanced contrast / clarity) beyond the limit due to photo damage in ordinary microscopes. “In photo damage, Bowen refers to the way a laser bombardment photons can degrade or destroy a microscope measure, similar to the way ants get crispy under a magnifying glass.
Microscopes have allowed humans to understand biology on a deeper level since the 16th century, and today’s advanced microscopes are so much more than a pair of aligned lenses. Innovations such as scanning of tunnel microscopescan for example see individual atoms. In the new work, the researchers shone brightly laser light on a yeast cell to reveal the complications of its substructures. They were able to get the higher resolution they wanted, thanks to the entangled photons, as “detecting one photon gives you information about when the next photon will arrive,” Bowen explained.
“This experiment is a beautiful example of how quantum techniques are now being utilized for a better understanding of biological processes,” said Clarice Aiello, a quantum engineer specializing in nanoscale biophysics at UCLA, which is not affiliated with the newer paper. “Technical barriers … must be overcome before the technology becomes commercial, but this experiment is proof that quantum techniques developed decades ago can and will be used to great advantage in the life sciences.”
While other microscopes that work with such intense light end up with sizzling holes in what they are trying to study, the team’s method did not. The researchers chemically fingerprinted a yeast cell using Raman spread, which observes how some photons scatter from a given molecule to understand the vibration signature of that molecule. Raman microscopes are often used for this kind of fingerprint, but the whole thing that destroys-what-we-try-to-observe has long troubled scientists trying to see in higher resolutions. In this case, the team could see the lipid concentrations of the cell using correlated photon pairs to get a good overview of the cell without increasing the intensity of the microscope’s laser beam.
Charles Camp, an electrical engineer at the National Institute of Standards and Technology, which specializes in Raman imaging, said in an email that Raman methods “have long promised to revolutionize biological imaging,” but have had various limitations. But in the new study, the researchers present “a proof-of-principle system and relatively practical way forward for improvement [stimulated Raman scattering] microscopy, ”Camp said.
“We were able to clearly solve the cell wall, which is a few nanometers thick structure that (of course) surrounds the cell,” Bowen said. “With other Raman microscopes, it is very difficult to fix the cell wall, and we showed in our case that our microscope could only very faintly see this without quantum correlations.”
Depending on who you are, it’s either scary or strangely comforting to think about how we’re all just a sum of cells, forged together at micro weights to form limbs and internal organs and all the complex systems that make us cross . But zoom in further, and there are even smaller biological structures that have yet to be fully understood. Impressive new imaging techniques allow us to skew a little harder in this completely unknown area.
This article has been updated with comments from Clarice Aiello and Charles Camp.
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