Holland E T, Vlastakis B, Heeres R W, Reagor M J, Vool U, Leghtas Z, Frunzio L, Kirchmair G, Devoret M H, Mirrahimi M, Schoelkopf R J
Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria.
Phys Rev Lett. 2015 Oct 30;115(18):180501. doi: 10.1103/PhysRevLett.115.180501. Epub 2015 Oct 26.
Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying an active feedback condition on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum-reservoir engineering protocol that stabilizes Fock states in a microwave cavity. This protocol is realized with a circuit quantum electrodynamics platform where a Josephson junction provides direct, nonlinear coupling between two superconducting waveguide cavities. The nonlinear coupling results in a single-photon-resolved cross-Kerr effect between the two cavities enabling a photon-number-dependent coupling to a lossy environment. The quantum state of the microwave cavity is discussed in terms of a net polarization and is analyzed by a measurement of its steady state Wigner function.
通过对辅助系统施加主动反馈条件或通过库工程，量子态可以在存在固有损耗和环境损耗的情况下得以稳定。库工程通过驱动和设计的熵排空相结合来维持所需的量子态。我们提出并实现了一种在微波腔中稳定福克态的量子库工程协议。该协议是在一个电路量子电动力学平台上实现的，其中一个约瑟夫森结在两个超导波导腔之间提供直接的非线性耦合。这种非线性耦合在两个腔之间产生单光子分辨的交叉克尔效应，使得能够与有损耗环境进行依赖于光子数的耦合。微波腔的量子态通过净极化来讨论，并通过对其稳态维格纳函数的测量进行分析。
