Speaker: Guojing Tian
Time: July 10 10:00-11:00, 2023
Venue: The second lecture hall of Conference Center, East Campus
Abstract:The Quantum State Preparation problem aims to prepare an n-qubit quantum state from the initial state, for a given unit vector. The problem is of fundamental importance in quantum algorithm design, Hamiltonian simulation and quantum machine learning, yet its circuit depth complexity remains open when ancillary qubits are available. In this talk, we study quantum circuits when there are m ancillary qubits available. This resolves the depth complexity for circuits without ancillary qubits. And for circuits with exponentially many ancillary qubits, our result quadratically improves the currently best upper bound.
Our circuits are deterministic, prepare the state and carry out the unitary precisely, utilize the ancillary qubits tightly and the depths are optimal in a wide parameter regime. The results can be viewed as (optimal) time-space trade-off bounds, which is not only theoretically interesting, but also practically relevant in the current trend that the number of qubits starts to take off, by showing a way to use a large number of qubits to compensate the short qubit lifetime.
Biography: Guojing Tian is an Associate Researcher of Institute of Computing Science, Chinese Academy of Sciences. She is also a Member of CCF Quantum Computing Group and CCF Theoretical Computer Committee. In 2017, she graduated fro
m Beijing University of Posts and Telecommunications, and her thesis was rated as an excellent doctoral dissertation by the China Communications Society (10 in total). Her research is on quantum algorithm design, quantum circuit optimization, quantum non-locality, quantum simulation, etc. She has published more than 20 papers in TCAD, PRR, QST, PRA, and other related international journals and conferences. She has presided over a number of projects of the Beijing Natural Science Foundation and National Natural Science Foundation and has been funded by Boxin Program (16 computer majors in China).