Lebreuilly José, Aron Camille, Mora Christophe
Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Université, Université Paris Diderot-Sorbonne Paris Cité, Paris 75005, France.
Laboratoire de Physique Théorique, École Normale Supérieure, CNRS, PSL University, Sorbonne Université, Paris 75005, France.
Phys Rev Lett. 2019 Mar 29;122(12):120402. doi: 10.1103/PhysRevLett.122.120402.
The controlled generation and the protection of entanglement is key to quantum simulation and quantum computation. At the single-mode level, protocols based on photonic cat states hold strong promise as they present unprecedentedly long-lived coherence and may be combined with powerful error correction schemes. Here, we demonstrate that robust ensembles of "many-body photonic cat states" can be generated in a Bose-Hubbard model with pair hopping via a spontaneous U(1) symmetry-breaking mechanism. We identify a parameter region where the ground state is a massively degenerate manifold consisting of local cat states which are factorized throughout the lattice and whose conserved individual parities can be used to make a register of qubits. This phenomenology occurs for arbitrary system sizes or geometries, as soon as long-range order is established, and it extends to driven-dissipative conditions. In the thermodynamic limit, it is related to a Mott insulator to pair-superfluid phase transition.
纠缠的可控生成与保护是量子模拟和量子计算的关键。在单模层面，基于光子猫态的协议极具前景，因为它们展现出前所未有的长寿命相干性，并且可以与强大的纠错方案相结合。在此，我们证明了通过自发的U(1)对称性破缺机制，在具有对跳迁的玻色 - 哈伯德模型中可以生成稳健的“多体光子猫态”系综。我们确定了一个参数区域，其中基态是一个高度简并的流形，由在整个晶格中因式分解的局域猫态组成，其守恒的个体宇称可用于制作量子比特寄存器。一旦建立了长程序，这种现象学对于任意系统尺寸或几何形状都会出现，并且它扩展到驱动 - 耗散条件。在热力学极限下，它与莫特绝缘体到对超流体的相变有关。
