The advent of laser technology has made it possible to obtain more intense and focused lights which, used in microscopy, have made it possible for scientists to observe details at very small scales. However, laser microscopy has a problem: samples can be degraded quickly in the process. To get around this obstacle, a team of researchers has developed a microscopy method based on quantum entanglement. The latter allowed them to observe details even more precisely without posing any danger to the sample.
In an article published in the journal Nature, Australian and German researchers have shown that quantum technologies offer a solution to the problems posed by laser microscopy. They built a quantum microscope that can more gently probe biological samples, allowing them to observe biological structures that would otherwise be impossible to see.
Creating a microscope that prevents damage to samples is a much anticipated step in quantum technology. It represents a first step in an exciting new era for microscopy, and more broadly for detection technologies. Microscopes have a long history. They are believed to have been first invented by Dutch lens maker Zacharias Janssen at the turn of the 17th century. He may have used them to counterfeit coins.
The problem with laser microscopy
This turbulent start led to the discovery of bacteria, cells and essentially all of microbiology as we now understand it. The more recent invention of lasers has provided a new type of focused light. This made possible a whole new approach to microscopy. Laser microscopes allow us to see biology in truly deep detail, 10,000 times smaller than the thickness of a human hair.
They were the subject of the Nobel Prize in chemistry in 2014 and have transformed our understanding of cells and the molecules like the DNA they contain. However, laser microscopes face a major problem. The very quality that makes them successful – their intensity – is also their Achilles heel. The best laser microscopes use light billions of times brighter than sunlight on Earth. In a laser microscope, biological samples can be degraded or destroyed in seconds.
The benefits of quantum entanglement
Other microscopes need to increase the intensity of the laser to improve the clarity of the images. By reducing noise via the quantum entanglement of the laser’s photons, the laser is able to improve clarity without increasing intensity. Alternatively, it is possible to use a less intense laser to produce the same microscope performance.
One of the main challenges was to produce quantum entanglement bright enough for a laser microscope. To do this, the researchers concentrated the photons into laser pulses of just a few billionths of a second. This produced an entanglement 1,000 billion times brighter than what was previously used in imaging.
When used in a microscope, this entangled laser light provides 35% better image clarity than is otherwise possible without destroying the sample. The authors used the microscope to image the vibrations of molecules in a living cell. This allowed them to see a detailed structure that would have been invisible with traditional approaches.
Quantum technology: a revolution in many fields
Quantum technologies are expected to have revolutionary applications in computing, communications and sensing. Quantum entanglement underlies many of these applications. A major challenge for researchers in quantum technology is to show that it offers absolute advantages over current methods.
Entanglement is already used by financial institutions and government agencies to communicate with guaranteed security. It is also at the heart of quantum computers, which Google showed in 2019 can perform calculations that would be impossible with current conventional computers.
Quantum sensors are the last piece of this puzzle. They should improve just about every aspect of our worldview, from better navigation to better health care and medical diagnostics. About a year ago, quantum entanglement was integrated into kilometer-scale gravitational wave observatories. This allows scientists to detect massive objects further out in space.
This work shows that entanglement can provide an absolute detection advantage at more normal size scales and in popular technologies. This could have big ramifications – not only for microscopy, but also for many other applications such as global positioning, radar, and navigation.