We study the equilibrium and non-equilibrium physics of two qubits interacting through an ultrastrong coupled qubit-cavity system. By tuning the qubits energy gap while keeping the ultrastrong coupling system to its ground state, we demonstrate a strong two-qubit interaction as well as an enhanced excitation transfer between the two qubits. Our proposal has twofold implications: a means to attain multipurpose parity-protected quantum information tasks in superconducting circuits, and a building block for ultrastrong coupled cavity-enhanced exciton transport in disordered media.
Many-body topology in parity-preserving tensor networks
Institut für Theoretische Physik, Universität zu Köln（科隆大学理论物理研究所）；London Centre for Nanotechnology, University College London（伦敦大学学院纳米技术伦敦中心）；Institute of Quantum Control, Peter Grünberg Institut (PGI-8), Forschungszentrum Jülich GmbH（于利希研究中心量子控制研究所，彼得·格林伯格研究所（PGI-8））
Extending matchgates into universal quantum computation
匹配门是与非相互作用费米子相关的双量子比特门家族。如果仅作用于最近的邻居，则它们是经典的可模拟的，但是如果我们放松该限制或使用SWAP门，则它们对于量子计算变得通用[Jozsa和Miyake，Proc.R. A 464，3089（2008）]。我们推广这一结果，证明任何nonmatchgate奇偶保持酉是能够扩展到通用量子计算的计算能力的matchgate。我们确定了单一的本地不变的宇称保持酉负责这一点，并讨论了相关的结果在费米子系统的背景下。
