Sep 2, 2022

New Method to Systematically Find Optimal Quantum Operation Sequences
for Quantum Computers Developed


Overview of the press release

The National Institute of Information and Communications Technology (NICT, President: TOKUDA Hideyuki, Ph.D.), Keio University (President: ITOH Kohei, Ph.D.), Tokyo University of Science (President: Dr. ISHIKAWA Masatoshi), The University of Tokyo (President: Dr. FUJII Teruo), succeeded for the first time in developing a method for systematically finding the optimal quantum operation sequence for a quantum computer.

In order for a quantum computer to perform a task, we need to write a sequence of quantum operations. Until now, computer operators have written their own quantum operation sequences based on existing methods (recipes). What we have developed this time is a systematic method that applies optimal control theory (GRAPE algorithm) to identify the theoretically optimal sequence from among all conceivable quantum operation sequences.

This method is expected to become a useful tool for medium-scale quantum computers and is expected to contribute to improving the performance of quantum computers and reducing environmental impact in the near future.

This result was published in the American scientific journal "Physical Review A" on August 23, 2022.


Image title:Quantum operation sequence (conceptual diagram)
Image caption:The six horizontal blue lines represent six qubits, with the input on the left and the output on the right. Operations are executed from left to right. Each red square represents a 1-qubit operation, and each green vertical line connecting two blue lines represents a 2-qubit operation. The optimal quantum operation sequence is realized with the fewest operations.

Professor kouichi Semba (Institute for Photon Science and Technology, Faculty of Science, Graduate School of Science, The University of Tokyo) contributed to this research.


To read the full press release, please visit the website of National Institute of Information and Communications Technology


Publication details

Journal Physical Review A
Numerical analysis of quantum circuits for state preparation and unitary operator synthesis


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