Microwave quantum optics on superconducting circuits

我在本财政年度的工作包括开发一个微波光子到一维波导的单向发射器。这项工作是关于制造一维量子网络的前景特别感兴趣，其中耦合到公共波导的量子比特可以彼此交换量子信息。事实上，如果没有某种特定的设计，导致在一个方向上发射，右或左，量子位将自然地在波导的两个方向上发射，这将因此在不同的位置散射量子信息。吸收也是如此。如果来自波导的光子从单个方向撞击在通常的量子位上，则量子位将不能吸收全部光子。另一方面，我提出的设备可以单向吸收和发射光子，这使我们能够绕过这个问题。现在的目的是演示这些单向器件中的一个耦合到开放传输线的操作。我的大部分时间都花在从理论的角度预测我们正在考虑的系统的行为上。通过将系统的物理编码成矩阵和方程，我们可以计算给定物理系统在时间上的时间演化，并推断出它在未来的状态。所有这些模拟都是使用Python编程语言进行的。

My work in this fiscal year consisted in developing a unidirectional emitter of　microwave photons to a 1D waveguide. This work is of particular interest　regarding the prospect of fabricating 1D quantum networks, where qubits coupled to a common waveguide can exchange quantum information with one another. Indeed, without some specific design that will lead to emission in a single direction, right or left, a qubit will naturally emit in both directions of the waveguide, which will thus scatter the quantum information in different locations. The same goes for absorption. If a photon from the waveguide impinges on a usual qubit from a single direction, the qubit will not be able to absorb the full photon. The device I propose, on the other hand, can absorb and emit photons unidirectionally, which allows us to circumvent this issue. The aim for now is to demonstrate the operation of a single of those unidirectional devices, coupled to an open transmission line. A large part of my time was devoted to predicting the behaviour of the systems we are considering from a theoretical point of view. By encoding the system’s physics into matrices and equations, we can calculate the time-evolution of a given physical system in time and deduce what will be its state at a future time. All these simulations were made using the Python programming language.