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Study: Quantum Computing 'Noise' Useful for Sustainable Energy

• By John K. Waters
• 02/04/2020

Scientists from IBM Research and the University of Notre Dame have shown that the environmental "noise" that destroys the fragile quantum state of qubits, and typically impedes quantum computer use, can actually be an advantage over classical computing in chemical simulations.

Among other things, this insight could lead researchers working on such complex chemical phenomena as solar energy conversion, artificial photosynthesis, and photovoltaics to engineer quantum noise for better simulations and experiments.

IBM and Notre Dame researchers conducted the study with the help of students at Georgetown University, DePaul University, Illinois Institute of Technology. and Occidental College in Los Angeles. They used a cloud-based IBM quantum computer to simulate how the outcome of a chemical reaction is controlled by the time evolution of the entangled state of the two reactants, and how this "spin chemistry" phenomenon is affected by the gradual loss of magnetization and dephasing (loss of synchronization) caused by thermal fluctuations.

Spin chemistry, a subfield of chemistry that deals with magnetic spin effects in chemical reactions, is at the heart of this study. "It connects quantum phenomena, such as superposition and entanglement, to tangible chemistry parameters, such as reaction yield (the amount of whatever a chemical reaction produces)," IBM researcher Barbara Jones and Notre Dame computing research specialist Mariya Vyushkova, explained in a blog post. "With a quantum computer, spin chemistry allows us to directly simulate some dynamic chemical processes, basically the kinetics of chemical reactions. Spin effects in radical pairs play an important role in processes underlying solar energy conversion."

Quantum noise can arise from control electronics, heat, or impurities in the materials in the quantum bits (qubits) themselves. This is generally considered a downside of quantum computing, but in earlier research, Notre Dame scientists found it necessary to introduce artificial noise to their classical computers to realistically mimic chemical reactions.

In 2018, the researchers "jumped at the chance" to create more detailed spin chemistry simulations using IBM's publicly available five-qubit quantum computers, Jones and Vyushkova explained. By April 2019, Notre Dame had joined the IBM Q Network, which offered them access to IBM's quantum computing systems and the "expertise they sought to carry out their spin chemistry experiments."

The researchers used the OpenPulse programming language via the Qiskit open-source quantum-computing framework to specify pulse-level control on Big Blue's quantum computer and slow down the calculations typically made by a program, so they could see the quantum computer's noise processes. This produced something of a side benefit of this research: insight into qubit noise.

"Noise is a natural property of qubits, but limits the number of calculations they can perform and introduces errors to the final results," the researchers wrote. "As we continue our work in this area, we will be able to contribute to the knowledge of those studying how to mitigate such noise and create more robust and less error-prone quantum computers in the future."

The results of the research by Jones and Vyushkova were published in "Simulation of Quantum Beats in Radical Pairs on a Noisy Quantum Computer," which is available as a free download. The list of authors on the paper also includes Brian Rost, Aaila Ali, Charlotte Cullip, Alexander Vyushkov, and Jarek Nabrzyski.