Quantum computers could help sharpen images of exoplanets

Quantum computers can help us see more exoplanets – and see them in more detail, too.

Astronomers have discovered thousands of planets beyond our solar system, but they estimate that there are actually billions of these exoplanets. Identifying and studying them is an integral part of the search for extraterrestrial life, but it is technically difficult because they are so far from Earth.

Johannes Borregaard of Harvard University and his colleagues say quantum computers could significantly improve the process.

To image exoplanets, researchers must collect light signals emitted by these planets, but these signals tend to be weak after traveling great distances through space. Additionally, signals are often made noisy or partially obscured by light from nearby stars.

Borregaard says his NASA colleagues helped him understand that the problem could be as difficult as searching for a single particle of light, or photon, for every second a telescope is operating.

Processing such weak signals is difficult with conventional methods, but a quantum computer could store a series of quantum states of incoming photons and then exploit their quantum properties to extract information about the exoplanet, he says. In this way, an analysis that would normally only produce an image that is too blurry to distinguish an exoplanet from its star – or which renders it as a single fuzzy dot – could produce sharper representations of the exoplanet in space. This could even allow researchers to detect the light fingerprints of the exoplanet’s molecules.

This is the idea at the center of his team’s project, where light from an exoplanet would first hit a quantum computing device made from specially designed diamonds. Similar devices have already been successfully tested as devices for storing the quantum states of photons. Then, these states would be communicated to another, more sophisticated quantum computer, which would then run an algorithm designed to extract the information needed to produce an image of the exoplanet. Borregaard and his colleagues modeled this second device as being made of extremely cold atoms, another technology that has recently shown great promise in experiments.

The researchers’ calculations showed that using quantum devices in this way could create images containing only hundredths or even thousandths of the number of photons currently required by traditional methods. In other words, the quantum setup could outperform current techniques when the light is very weak.

“Photons obey the rules of quantum mechanics, so it is natural and logical to study quantum methods to detect and process light coming from, for example, exoplanets,” explains Cosmo Lupo of the Polytechnic University of Bari in Italy. However, he says that making this new proposal a reality would be a complex challenge and would require both very good control of the performance of each of the two quantum computers and an efficient way of connecting them.

Borregaard sees the situation the same way. Although there is promising experimental work that strengthens the case for using both the diamond-based quantum computer and the ultra-cold quantum computer, several research groups, including his colleagues, are currently working on linking the two, he says.

Lupo says another system for harnessing the quantum nature of light has already been used to observe a star in the constellation Canis Minor, so the trend toward using quantum devices to observe space is already underway. “I am excited to see the impact that quantum computing will have on the field of imaging and astronomy in the future,” he says. “The new work is an important first step in this direction.”

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