近日，法国巴黎萨克雷大学的P. Roulleau及其研究团队取得一项新进展。经过不懈努力，他们实现石墨烯中列维子的发射和相干控制
在这项工作中，研究人员设计了按需注入单个电子飞行量子比特状态及其在布洛赫球上的操纵。飞行的量子比特是在高迁移率单层石墨烯的量子霍尔边缘通道中传播的列维子（Leviton）。虽然单次量子比特读出和双量子比特操作仍然需要对飞行量子比特进行可行的操纵，但在单电子水平上对流动电子态的相干操纵是传统量子比特的一个非常有前途的替代方案。
据悉，飞行量子比特以传播模式编码量子信息，而不是以固定的离散状态编码。虽然光子飞行量子比特是可用的，但光子之间的弱相互作用限制了条件量子门的效率。相反，电子飞行量子比特可以利用库仑相互作用，但传统半导体中较弱的量子相干性阻碍了它们的实现。
附：英文原文
Title: Emission and coherent control of Levitons in graphene
Author: A. Assouline, L. Pugliese, H. Chakraborti, Seunghun Lee, L. Bernabeu, M. Jo, K. Watanabe, T. Taniguchi, D. C. Glattli, N. Kumada, H.-S. Sim, F. D. Parmentier, P. Roulleau
Issue&Volume: 2023-12-15
Abstract: Flying qubits encode quantum information in propagating modes instead of stationary discrete states. Although photonic flying qubits are available, the weak interaction between photons limits the efficiency of conditional quantum gates. Conversely, electronic flying qubits can use Coulomb interactions, but the weaker quantum coherence in conventional semiconductors has hindered their realization. In this work, we engineered on-demand injection of a single electronic flying qubit state and its manipulation over the Bloch sphere. The flying qubit is a Leviton propagating in quantum Hall edge channels of a high-mobility graphene monolayer. Although single-shot qubit readout and two-qubit operations are still needed for a viable manipulation of flying qubits, the coherent manipulation of an itinerant electronic state at the single-electron level presents a highly promising alternative to conventional qubits.
Source: https://www.science.org/doi/10.1126/science.adf9887