Quantum Advantage in Reversing Unknown Unitary Evolutions

演讲人: 陈俣翱 香港中文大学(深圳)
时间: 2024-04-17 19:15-2024-04-17 20:14
地点:线上会议 (tx:362-210-030 ps:1984)

We introduce the Quantum Unitary Reversal Algorithm (QURA), a deterministic and exact approach to universally reverse arbitrary unknown unitary transformations using O(d^2) calls of the unitary, where d is the system dimension. Our construction resolves a fundamental problem of time-reversal simulations for closed quantum systems by affirming the feasibility of reversing any unitary evolution without knowing the exact process. The algorithm also provides the construction of a key oracle for unitary inversion in quantum algorithm frameworks such as quantum singular value transformation. Notably, our work demonstrates that compared with classical methods relying on process tomography, reversing an unknown unitary on a quantum computer holds a quadratic quantum advantage in computation complexity. QURA ensures an exact unitary inversion while the classical counterpart can never achieve exact inversion using a finite number of unitary calls.


Dr. Yu-Ao Chen received his PhD degree from the Academy of Mathematics and Systems Science at the Chinese Academy of Science in 2020. Then he worked as a senior researcher at the Institute for Quantum Computing at Baidu Research, concentrating on quantum algorithm and the development of the Baidu Quantum platform. Presently, he is a research associate at the Quantum AI Research Lab, Thrust of Artificial Intelligence, Information Hub, Hong Kong University of Science and Technology (Guangzhou). Dr. Yu-Ao Chen’s current research interests focus on quantum computing and symbolic computation.