Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
Laboratory for Physical Sciences, College Park, Maryland 20740, USA.
Nat Commun. 2017 Jan 27;8:14148. doi: 10.1038/ncomms14148.
The deterministic generation of non-classical states of light, including squeezed states, Fock states and Bell states, plays an important role in quantum information processing and exploration of the physics of quantum entanglement. Preparation of these non-classical states in resonators is non-trivial due to their inherent harmonicity. Here we use stimulated Raman adiabatic passage to generate microwave photon Fock states in a superconducting circuit quantum electrodynamics system comprised of a fixed-frequency transmon qubit in a three-dimensional microwave cavity at 20 mK. A two-photon process is employed to overcome a first order forbidden transition and the first, second and third Fock states are demonstrated. We also demonstrate how this all-microwave technique can be used to generate an arbitrary superposition of Fock states. Simulations of the system are in excellent agreement with the data and fidelities of 89%, 68% and 43% are inferred for the first three Fock states respectively.
光的非经典态（包括压缩态、Fock 态和贝尔态）的确定性产生在量子信息处理和量子纠缠物理的探索中起着重要作用。由于谐振器固有的谐和性，在谐振器中制备这些非经典态并非易事。在这里，我们使用受激拉曼绝热通道在超导电路量子电动力学系统中生成微波光子 Fock 态，该系统由 20mK 下三维微波腔中的固定频率超导量子比特组成。采用双光子过程来克服一阶禁戒跃迁，并演示了第一、第二和第三 Fock 态。我们还展示了如何使用这种全微波技术生成 Fock 态的任意叠加。系统的模拟与数据非常吻合，推断出前三个 Fock 态的保真度分别为 89%、68%和 43%。
