Scalable Quantum Optimal Control

Nils Petersson | 20-ERD-028

Project Overview

Quantum optimal control can be used to shape the control pulses for realizing unitary and nonunitary transformations of quantum states. These control pulses provide the fundamental interface between the quantum compiler and the quantum hardware. Most current software for quantum optimal control is restricted to run on shared memory platforms, limiting their applicability to smaller quantum systems, especially if interactions with the environment are considered. The main objective of this LDRD project was to address the need for simulation and optimal control of larger quantum systems, beyond what is possible with current codes. To meet this objective, we developed new simulation and optimal-control methodologies that allow larger quantum systems to be handled through scalable implementations aimed at modern high-performance computing (HPC) platforms. Two open-source codes (Juqbox.jl and Quandary) were developed by this LDRD project, aimed at closed and open quantum systems. For closed systems, the optimization method in Juqbox.jl shows superior convergence compared to existing software, and control pulses were experimentally validated with 99.4 % fidelity. For open quantum systems, the Quandary code demonstrated a speed-up of 328x over a serial calculation for a 12-qubit case, illustrating that optimal control of open quantum systems is made possible by using modern HPC machines.

Mission Impact

During this LDRD project, collaborations with researchers at Fermi labs, NYU, MSU, and the University of Chicago have been established. These researchers are now using the open-source codes developed by this project. These collaborations are expected to result in additional publications, under support by funding from the TEAM project, funded by ASCR. As an outcome of the science and technology tools developed by this LDRD project, LLNL researchers will be able to accelerate the realization of practical high-performance quantum computing technologies and help position the Lab as a world leader in the emerging fields of quantum sensing, control, and scientific quantum computing. These capabilities will be essential for meeting future national-security challenges.

Publications, Presentations, and Patents

Lee, S., et al. 2022. "Compositional Methods for Schroedinger's Equation with Application to Optimal Control." Summer Student Project, Livermore, CA. September 2022. LLNL-TR-839943.

Li, K., and N. A. Petersson. 2022. "Infidelity Associated with Eliminating the Bus Resonator." Summer Student Project, Livermore, CA. September 2022. LLNL-TR-839845.

Garcia, F. M., and N.A. Petersson. 2022. "Hamiltonian Simulations Using Quantum Circuit Diagonalization." IBM Open Science Prize Challenge 2021-22, Virtual. April 2022. LLNL-TR-834268.

Baker, J. M., et al. 2022. "Synthesizing Efficient Pulses for Practical Qudit Circuits." Poster, Quantum Information Processing (QIP) Conference, Shenzhen, China. March 2022. LLNL-POST-832501.

Petersson, N. A., et al. 2021."An Open-Source C++ Package for Optimal Control of Open Quantum Systems on High-Performance Computers." Invited presentation, Advanced Research in Quantum Computing Seminar, December 2021. Virtual. LLNL-PRES-829857.

Guenther, S., et al. 2021. "Quandary: An Open-Source C++ Package for High-Performance Optimal Control of Open Quantum Systems." 2021 IEEE/ACM 2nd Int. Workshop on Quantum Computing Software, St Louis, MO. November 2021; doi: 10.1109/QCS54837.2021.00014.

Guenther, S., et al. 2021. "Quantum Optimal Control for Pure-State Preparation Using One Initial State." AVS Quantum Science 3(4): 043801 (2021); doi: 10.116/5.0060262.

Petersson, N.A., et al. 2021. "Numerical Optimal Control of Quantum Systems." Presentation, American Physical Society, Virtual. March 2021. LLNL-PRES-820605.

Petersson, N. A., and F. M. Garcia. 2021. "Juqbox.jl: Optimal Control of Closed Quantum systems in Julia." Open-source Software Release, Github, March 2021. LLNL-CODE-820043.

Petersson, N. A., et al. 2021. "IBM Open Science Prize: SWAP Gate Challenge." IBM Open Science Prize Challenge 2020-21, Virtual. April 2021. LLNL-TR-821599.

Petersson, N. A., et al. 2021. "Numerical Optimal Control of Quantum Systems." Invited presentation, George Mason University, Virtual. March 2021. LLNL-PRES-820605.

Guenther, S. 2021. "Quandary: Optimal Control for Open and Closed Quantum Systems." Open-source Software Release, Github, January 2021., LLNL-CODE-817714.

Guenther, S., and N. A. Petersson. 2021. "Quandary: Optimal Control for Quantum Systems." Software manual, January 2021. LLNL-SM-818073.

Garcia, F. M., et al. 2022. "JuQBox: A Quantum Optimal Control Toolbox in Julia." Presentation, 1st Int. Workshop on Quantum Computing Software, St Louis, MO. November 2020. LLNL-PRES-816493.

Wu, X., et al. 2020. "High-Fidelity Software-Defined Quantum Logic on a Superconducting Qudit." Phys. Rev. Lett. 125 (2020); doi: 10.1103/PhysRevLett.125.170502.

Petersson, N.A., et al. 2020. "Constructing Parsimonious Control Functions Using B-Splines with Carrier Qaves." Poster, American Physical Society, Denver, CO. March 2020. LLNL-POST-805736.