Quantum computers in action in chemistry

Quantum computers in action in chemistry
Schematic representation of the decomposition of the interaction Hamiltonian W into local terms Wlocal,i and a nonlocal term Wnon−local for a situation with six one-particle states and two states per local interaction term. Black dots represent the one-particle states. Credit: Physical Review Research (2022). DOI: 10.1103/PhysRevResearch.4.033160

Quantum computers are one of the key future technologies of the 21st century. Their potential surpasses even the best supercomputers. They have proven to be a powerful tool, in particular for solving complex computational problems—a task that pushes the limits of classical hardware.

One promising application for is , where it is used to solve, for example, the electronic Schrödinger equation to predict the atomic structure of materials or molecules. In research, are essential for treating such issues. With , however, this is only possible to a limited extent on classical computers.

Researchers at Paderborn University have now found a way to efficiently run simulations with on quantum computers, which should provide information about their energies and . The researchers focus on parallelization and propose a new algorithm and techniques for reducing the qubit count, the number of quantum programs and the depth of these programs. The aim is to minimize the error rate, among other things. Their findings were recently published in the journal Physical Review Research.

'It makes the problem parallelizable'

Although quantum computers have the edge when it comes to solving complex computing tasks, they require extremely high computing resources to do this. The efficient investigation of chemical properties still therefore poses a challenge today. But, qubits—the fundamental units of information in quantum computing—make this possible. These are, however, prone to error, resulting in quantum noise.

Professor Thomas D. Kühne and his colleagues at Paderborn University have come up with a solution to this: "We have developed a , which we have used to divide complex calculations into several small sub-units. This reduces the required qubit count and makes the problem parallelizable. This means that calculations are performed one after the other," explains Kühne, who heads up the university's Theoretical Chemistry working group.

Dr. Robert Schade, a scientific advisor at the new high-performance computing center at the Paderborn Center for Parallel Computing (PC²) who is also involved in the project, adds, "This means that much larger molecules than before can be simulated on a quantum computer with a given qubit count and their electronic structure studied. Due to its specific nature, the proposed algorithm also has a high noise tolerance. This means that calculations are numerically stable, despite the noise."

Approximate computing: Approximate results suffice

"Noise in the nuclear forces that virtually hold the particles together can be compensated for in simulations in the spirit of , whereby accuracy of calculations is abandoned in favor of a reduction in runtime or the required electrical power. Therefore, instead of accurate results, what you work with are approximate results, which are perfectly sufficient. The investigation of the representability of very special quantum states, the optimization of the measurement programs and the integration with molecular dynamics programs are the subject of future research," says Professor Christian Plessl, Director of the Paderborn Center for Parallel Computing (PC²) at Paderborn University. The researchers are confident that the method they have developed will be suitable for use in quantum computers in the future.

More information: Robert Schade et al, Parallel quantum chemistry on noisy intermediate-scale quantum computers, Physical Review Research (2022). DOI: 10.1103/PhysRevResearch.4.033160

Citation: Quantum computers in action in chemistry (2022, October 13) retrieved 30 March 2023 from https://phys.org/news/2022-10-quantum-action-chemistry.html
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