A team of researchers in Germany and Australia recently used a new microscopy technique to image nano-scale biological structures at a previously unmanageable resolution, without destroying the living cell. The technique, which employs laser light many millions of times brighter than the Sun, has implications for biomedical and navigation technologies.
The quantum optical microscope is an example of how the strange principle of quantum entanglement can feature in real-world applications. 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’s microscope, described in a paper published today in Science, hinges on quantum light—entangled pairs of photons—to see better-resolved structures without damaging them.
“The key question we answer is whether quantum light can allow performance in microscopes that goes 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 that, in fact, it can. “We demonstrate [that] for the first time, showing that quantum correlations can allow performance (improved contrast/clarity) beyond the limit due to photodamage in regular microscopes.” By photodamage, Bowen is referring to the way a laser bombardment of photons can degrade or destroy a microscope’s target, similar to the way ants will get crispy under a magnifying glass.
“Technical hurdles … will need to be overcome before the technology becomes commercial, but this experiment is a proof-of-principle that quantum techniques developed decades ago can and will be deployed to great advantage in the life sciences.”
While other microscopes operating with such intense light end up sizzling holes in what they’re trying to study, the team’s method didn’t. The researchers chemically fingerprinted a yeast cell using Raman scattering, which observes how some photons scatter off a given molecule to understand that molecule’s vibrational signature. Raman microscopes are often used for this sort of fingerprinting, but the whole destroying-the-thing-we’re-trying-to-observe has long vexed researchers trying to see in higher resolutions. In this case, the team could see the cell’s lipid concentrations by using correlated photon pairs to get a great view of the cell without increasing the intensity of the microscope’s laser beam.