EAGER: Chemically-Inspired, Tunable Quantum Computing Architectures for Dynamics of Molecular Systems

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Philip Richerme and Srinivasan Iyengar of Indiana University, are developing quantum devices inspired by and for the study of quantum chemical dynamics. The chemical processes studied by Richerme and Iyengar play central roles in the reactive chemistry of most biological, materials, and atmospheric systems.

For instance, quantum chemical dynamics likely underlie catalytic transformations of global importance, including the reduction of CO2, which is critical to converting this greenhouse gas to useful feedstocks, artificial photosynthesis, and nitrogen fixation. Classical approaches toward modeling these processes have been unsuccessful, since they would require exponentially large computing resources to accurately describe the large numbers of quantum-mechanical electrons and nuclei within the system.

Instead, Richerme and Iyengar will use fundamentally quantum hardware, whose design mirrors the geometry of the molecules under study, to emulate the dynamics of these chemical systems. This may allow them to directly calculate wavepacket dynamics and vibrational spectra for these systems without the significant overhead of gate-model quantum computation.

In addition, this project will provide a rich training environment for experimental and theory graduate students – both at the MS and PhD levels – and will enable the development of a Quantum Chemistry track within the Indiana University Quantum Master’s degree program, addressing the nationally-recognized need for workforce development in the area of Quantum Information Science.

Richerme and Iyengar will develop a new approach to mapping the microscopic quantum interactions of chemical systems to engineered quantum hardware. Their central insight is that the relative geometry of quantum objects drives their connectivity, and hence, behavior and offers significant simplifications when designing quantum hardware to emulate natural processes.

Drawing inspiration from the geometry of the molecules themselves, they arrange the geometry of trapped-ion qubit arrays to natively replicate the interactions and timescales of entanglement propagation between the various nuclear degrees of freedom. This approach is motivated by the observation that closely-spaced trapped-ion qubits interact strongly, while interactions decay quickly as the ion-ion distance is increased.

This difference in coupling strengths, emerging from the relative ion positions, provides a framework in which multiple nuclear dimensions are simulated in parallel within multiple closely-spaced groups of ions; weak couplings across these ion clusters then generates correlations among the effective nuclear degrees of freedom. The spacing between ion clusters is controllable to sub-micron precision by changing the confinement voltages applied to ion-trap electrodes, similar to prior work which controls the trap voltages to achieve equally-spaced ion strings.

Once these native interactions are encoded through the system geometry, analog quantum simulation methods should enable propagation of the molecular dynamics and extraction of the vibrational frequencies in the system, without requiring exponential numbers of quantum gates. Success in this approach has the potential to be transformational in the fields of quantum dynamics and vibrational spectroscopy.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.