Quantum dynamics of Josephson fluxons

基本超导量子电路的量子特性，即所谓的量子比特，在过去的十年里引起了人们的极大兴趣，并且在其相干时间方面取得了巨大的进步。到目前为止，大多数研究的目的是开发通用量子计算机的构建模块和控制工具，另一方面，用很少的超导量子比特和微波光子测试量子物理学的基本定律。构建和操纵具有大量量子组件的超导电路仍然是一个巨大的挑战，因为它们的量子态非常复杂，并且未知的相干极限。该项目的主要思想是从实验和理论上探索超导量子比特网络中集体激发的量子动力学和相干性。特别是，我们的兴趣将是探索和理解它们的空间局域化激发的量子动力学-磁通子，这是由持续的超导涡流形成的拓扑稳定的磁通量量子。我们的目标是观察磁通子的相干隧穿和探测它们的布洛赫振荡。我们将用一维超导网络进行实验，并测量它们在微波波段的激发谱。我们希望通过Aharonov-Casher干涉施加门电荷来控制量子通量子的迁移率。我们计划的目标将是找到利用通量子的量子动力学来操纵纠缠和在芯片上传输量子信息的方法。这将使可扩展的量子处理器及其与经典单通量逻辑的接口的新方法的开发成为可能。

Quantum properties of elementary superconducting quantum circuits, so-called qubits, attracted a lot of interest in the past decade and tremendous improvements in their coherence times have been made. Most of research to date has been aimed at developing building blocks and control tools for universal quantum computer, on the one hand, and at testing fundamental laws of quantum physics with few superconducting qubits and quantum optics with microwave photons, on the other hand. Building and manipulating superconducting circuits with larger number of quantum components remains a big challenge due to the overwhelming complexity of their quantum states and unknown coherence limits. The main idea of the project is to experimentally and theoretically explore quantum dynamics and coherence of collective excitations in networks of superconducting qubits. In particular, our interest will be on exploring and understanding quantum dynamics of their spatially-localized excitations – magnetic fluxons, which are topologically stable magnetic flux quanta formed by vortices of persistent supercurrents. We are aiming at observing coherent tunnelling of fluxons and detecting their Bloch oscillations. We will perform experiments with one-dimensional superconducting networks and measure their excitation spectra in the microwave band. We hope to control the mobility of quantum fluxons by applying gate charges through the Aharonov-Casher interference. The goal of our program will be on finding ways to employ quantum dynamics of fluxons for manipulating entanglement and transferring quantum information across the chip. This should enable development of novel approaches towards scalable quantum processors and their interfaces with classical single-fluxon logic.