纠缠Dicke态的确定性制备

中文摘要 AI 辅助

N个原子构成的集合的Dicke态$|J=N/2,m\rangle$是Dicke超辐射理论的核心。除了完全极化的端态外，它们是纠缠多体态；其中，单激发Dicke态是量子信息科学中熟知的W态。然而，确定性制备具有指定自旋投影的Dicke态仍具挑战性，尤其是不依赖后选择或预示的情况。本文提出一种失谐编程哈密顿量协议，使用处于色散腔中的原子或量子比特，该腔受相干横向驱动。无驱动时，失谐腔产生有效集体自旋相互作用。通过结合这种腔介导相互作用与相干驱动，调节原子-驱动失谐原则上可使协议靶向对称Dicke阶梯上的任意允许Dicke态。从横向驱动基态出发，绝热基态插值通过降低驱动强度同时增强腔介导相互作用，制备选定的Dicke态。制备完成后，将腔调谐至与原子或量子比特共振，为探测所制备Dicke态的集体发射响应提供直接方法。本文讨论了在超导电路QED中的实现，并表明所制备的态，尤其是$m=0$的中心Dicke态，为具有海森堡极限标度的量子传感提供资源。

英文摘要

Dicke states $|J=N/2,m\rangle$ of a collection of $N$ atoms were central to Dicke's theory of superradiance. Except for the fully polarized end states, they are entangled many-body states; in particular, the single-excitation Dicke state is the W state well known in quantum information science. However, deterministic preparation of Dicke states with a prescribed spin projection remains challenging, especially without relying on postselection or heralding. Here we present a detuning-programmed Hamiltonian protocol using atoms or qubits in a dispersive cavity subject to a coherent transverse drive. In the absence of the drive, the off-resonant cavity produces an effective collective-spin interaction. By combining this cavity-mediated interaction with the coherent drive, tuning the atom--drive detuning enables the protocol, in principle, to target any allowed Dicke state along the symmetric Dicke ladder. Starting from the transverse-drive ground state, adiabatic ground-state interpolation prepares the selected Dicke state by ramping down the drive strength while ramping up the cavity-mediated interaction. After preparation, tuning the cavity into resonance with the atoms or qubits provides a direct way to probe the collective-emission response of the prepared Dicke state. We discuss implementation with superconducting circuit QED and show that the prepared states, especially the central Dicke state with $m=0$, provide resources for quantum sensing with Heisenberg-limited scaling.

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6 pages, 2 figures