Ultrafast adiabatic passages in ultrastrongly coupled light-matter systems

TL;DR

This paper demonstrates a method for ultrafast, high-fidelity generation of multi-mode W states in ultrastrongly coupled light-matter systems using symmetry-protected adiabatic passages, expanding the understanding of adiabatic processes in quantum systems.

Contribution

It introduces a linear, symmetry-protected adiabatic passage technique for ultrafast generation of arbitrary single-photon W states in light-matter systems.

Findings

Achieved 99% fidelity in generating W states within 1.55 cycles of the system frequency.

Enlarged the minimum energy gap to 0.63ω with Stark shifts, enabling faster adiabatic processes.

Demonstrated the existence of linear ultrafast adiabatic passages in ultrastrong light-matter coupling.

Abstract

We have obtained the solutions of the multimode quantum Rabi model when all modes have identical frequencies $\omega$, including dark states $|\phi_K\rangle$ with at least $K$ $(K=1,2,3,\ldots)$ photons. Extended to the multiqubit case, they lie close to another dark state $\vert \psi\rangle$ with at most one photon in the spectrum. Taking advantages of such solutions, we find a linear and symmetry-protected adiabatic passage through $\vert \psi\rangle$ to fast generate arbitrary single-photon $M$-mode $W$ states $\vert W_M\rangle$ with exactly the same speed. The effective minimum energy gap during the adiabatic evolution is further enlarged to $0.63\omega$ when Stark shifts are included, such that arbitrary $\vert W_M\rangle$ can be ultrafast generated in $1.55\times 2\pi\omega^{-1}$ with fidelity $99\%$, indepedent of $M$. This work reveals the existence of linear ultrafast adiabatic passages in light-matter systems.