A Recipe for More Powerful Quantum Computers

Mathematicians from the University of Copenhagen have developed a method to enhance the ability of quantum computers to simulate complex quantum systems, such as molecules. Their findings were published in Nature Communications.

The development of a new drug can take over a decade and cost hundreds of millions to billions of euros, often involving numerous failures along the way. However, what if we could predict how a drug would affect the body before even starting laboratory tests, shortening the entire process from years to months?

Drugs consist of molecules made up of atoms, which behave according to quantum mechanics. Simulating their behavior requires a quantum computer, as traditional computers, regardless of power, cannot manage the immense amount of data with the same precision.

A team of physicists, computer scientists, and mathematicians at the University of Copenhagen’s Quantum for Life Centre has dedicated years to exploring how quantum simulators—a type of specialized quantum computer—can be used to simulate and predict molecular behavior.

It Is All About Size, Or Is It?

One fundamental issue that all quantum computer researchers face is size. Modern quantum computers can only simulate a few atoms, which poses a problem since the complex molecules in medicinal drugs often consist of millions of atoms.

The Quantum for Life team has now taken a significant step toward resolving this issue by developing a mathematical framework that simplifies programming for quantum simulators. This recipe will result in more computing power from a simulator of the same size.

Quantum simulators consist not only of quantum hardware but of quantum software too—essentially, the recipe for using the quantum simulator. With these new results, we are making a major leap on the software side, presenting a much better method than we’ve had before to scale up the existing hardware and solve more complex tasks.

Dylan Harley, Study First Author and Doctoral Student, Quantum for Life Centre, University of Copenhagen

It was previously thought that scaling up quantum simulators would require a complete hardware redesign. However, the new quantum algorithm offers a solution by forming the foundation of the quantum software. This algorithm introduces a controlled amount of noise to the particles being simulated, ensuring that the simulation proceeds smoothly without stalling. This concept is universal and can be applied to any quantum hardware, whether based on atoms, ions, or artificial atoms such as superconducting qubits.

Could Revolutionize Pharmaceutical Development

Quantum technology is seen as the key to creating the new and improved medicines of the future. But without the ability to scale quantum simulators effectively, their practical use is very limited. That is why it’s essential to find out how our quantum software can support this scaling. And now we have a recipe to do just that.

Matthias Christandl, Professor and Center Leader, Quantum for Life Centre, University of Copenhagen

Christandl emphasized the potential impact of a functional quantum simulator, stating, “If we can use a computer to simulate how a new drug will behave in a human body before conducting any experiments, it could fundamentally change the way we develop and test pharmaceuticals, which will significantly accelerate the amount of time from lab to patient.” 

The next step for the researchers is to test their mathematical formula on quantum hardware.

Dylan Harley, Frederik Ravn Klausen, Albert H. Werner, and Matthias Christandl from the Quantum for Life Centre, Department of Mathematical Sciences at the University of Copenhagen; Ishaun Datta from Stanford University; Andreas Bluhm from Université Grenoble Alpes, France; and Daniel Stilck França from Université de Lyon, France participated in the study.

Journal Reference:

Harley, D. et. al. (2024) Going beyond gadgets: the importance of scalability for analogue quantum simulators. Nature Communications. doi.org/10.1038/s41467-024-50744-9