中科院数学与系统科学研究院
数学研究所
学术报告
计算机科学研讨班
报告人： 袁佩 博士（腾讯实验室）
题 目：Does qubit connectivity impact quantum circuit complexity?
时 间：2023.04.03（星期一）14:30-15:30
地 点：数学院南楼N802
摘 要：Some physical implementation schemes of quantum computing -- such as those based on superconducting qubits, quantum dots, and cold atoms -- can apply two-qubit gates only on certain pairs of qubits. Other schemes -- such as those based on trapped ions and photonics -- are not subject to such constraints. These qubit connectivity constraints are commonly viewed as a disadvantage; for example, compiling an unrestricted 
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-ary trees and expander graphs, and show results similar to the 1D chain (path graph). Second, we consider the case when ancillary qubits are available. We show that, with ancilla, the circuit depth can be made polynomial, and the space-depth trade-off is not impaired by the qubit connectivity constraint unless we have exponentially many ancillary qubits. Third, we consider special families of unitaries, including diagonal unitaries, 2-by-2 block diagonal unitaries, and Quantum State Preparation (QSP) unitaries, the last being a fundamental task used in many quantum algorithms for machine learning and linear algebra problems.
个人简介：Pei Yuan is currently with Tencent Quantum Laboratory. She received her Ph.D. degree from Institute of Computing Technology, Chinese Academy of Sciences in 2021. Her research interests include quantum circuit optimization and quantum algorithms.
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