On-chip triple hybrid quantum systems: coupling microwaves to magnon-phonon polarons

“量子系统”描述了基本激发被量子化为小能量包的物理系统。例子包括光的单个光子，晶体的振动（声子）和磁系统的激发（磁振子）。控制这些基本激励的能力可以导致革命性新技术的发展，如量子计算机，通过量子加密的安全通信，以及用于导航，地球物理勘探和医学成像的传感技术。这些技术的关键是能够在不同的物理系统之间以一种连贯的方式传输能量量子，同时保留量子态内编码的信息。这是通过“重叠”或混合系统的量子态来实现的。许多研究小组正在研究在不同物理系统中实现量子混合的方法。最近，一个被称为“腔自旋电子学”的研究领域已经实现了微波光子、磁振子和声子之间的量子杂化。然而，这些实验需要体积庞大的厘米级微波腔和体积庞大的毫米级磁球，不适合技术应用的发展。我们提出的项目将开发一个完整的片上架构，用于在微米尺寸的铁磁元件中耦合微波光子与磁振子和声子。片上架构将使自己更容易与其他物理系统集成，如光学腔、声学谐振器和超导量子位（量子计算机的组成部分）。我们的建议将以最近的两个事态发展为基础。首先，我们开发了一种新的方法，在薄磁层中产生磁振子和声子态之间的大重叠，并在微米尺度的扩展磁结构中首次展示了磁振子-声子混合态。这是通过在层的表面绘制浅周期性条纹图案来实现的，这使得声子和磁振子模式受到限制，并导致它们重叠。其次，研究小组，包括我们在日立剑桥实验室的项目合作伙伴，最近已经开发出了在芯片架构中将微波光子与微米级磁性结构重叠的方法。这个建议将建立在这两个关键的发展，通过制造微波电路的电子芯片包含微米大小的图案磁结构，其中混合磁-声子状态形成。与片上微波电路中光子的重叠将导致所有三种系统（光子、磁振子和声子）之间的杂交。此外，微波电路可以很容易地控制和检测使用标准的实验室测量仪器。这将使我们能够利用微波激发和探测磁振子和声子。我们提出的完全片上混合光子-磁振子-声子系统将产生显着的技术优势，可能导致量子计算，通信和传感器技术领域的新应用。它将使研究光子、磁振子和声子的基本性质以及不同量子系统之间的相互作用成为可能。

"Quantum systems" describes physical systems in which the elementary excitations are quantised as small packets of energy. Examples include individual photons of light, vibrations of crystals (phonons), and excitations of magnetic systems (magnons). The ability to control these elementary excitations can lead to the development of revolutionary new technologies such as quantum computers, secure communication through quantum encryption, and sensing technologies for navigation, geophysical exploration and medical imaging. Crucial to these technologies is the ability to transfer the quanta of energy between different physical systems in a coherent way that preserves the information encoded within the quantum states. This is achieved by "overlapping" or hybridising the quantum states of the systems. Many research groups are working on ways to achieve quantum hybridisation in different physical systems. Recently, a field of research known as "Cavity Spintronics" has achieved quantum hybridisation between microwave photons, magnons and phonons. However, these experiments require bulky, centimetre-size microwave cavities and large, millimetre-size magnetic spheres, which are not suitable for the development of technological applications. The project we propose will develop a fully on-chip architecture for coupling microwave photons with magnons and phonons in a micron-size ferromagnetic element. The on-chip architecture will lend itself more easily to integration with other physical systems such as optical cavities, acoustic resonators and superconducting qubits (the building blocks of quantum computers).Our proposal will build upon two recent developments. Firstly, we have developed a novel method to create a large overlap between magnon and phonon states in thin magnetic layers and have demonstrated the first hybrid magnon-phonon state in a micron-scale extended magnetic structure. This was achieved by patterning the layer's surface with a shallow periodic stripe pattern, which created confinement of the phonon and magnon modes and caused them to overlap. Secondly, research groups, including our project partners at the Hitachi Cambridge laboratory, have recently developed methods to overlap microwave photons with micron-scale magnetic structures in on-chip architectures. This proposal will build upon these two key developments by fabricating microwave circuits on electronic chips containing micron-size patterned magnetic structures, in which hybrid magnon-phonon states are formed. The overlap with the photons in the on-chip microwave circuit will lead to hybridisation between all three systems (photons, magnons and phonons). Furthermore, microwave circuits can be readily controlled and detected using standard laboratory measurement instruments. This will allow us to excite and probe the magnons and phonons using the microwaves.Our proposal to make fully on-chip hybrid photon-magnon-phonon systems will yield significant technological advantages that could lead to new applications in the realms of quantum computing, communications and sensor technology. It will enable investigations of the fundamental properties of photons, magnons and phonons and of the interactions between the different quantum systems.