Three-body interaction in a magnon-Andreev-superconducting qubit system: collapse-revival phenomena and entanglement redistribution

TL;DR

The work addresses realizing a genuine three-body interaction among a magnon mode and two different qubits in a hybrid platform. By leveraging flux-mediated coupling in a YIG-based magnon system coupled to an ASQ and an SCQ, the authors derive an effective three-body Hamiltonian under resonance conditions such as $\omega_a=\omega_m+\omega_s$ and demonstrate synchronized collapse and revival of the two-qubit populations when the magnon starts in a coherent state. Importantly, during collapse, genuine tripartite entanglement is redistributed into bipartite entanglement between the two qubits and vice versa, with total entanglement conserved; this entanglement dynamics is further analyzed under dissipation and contrasted with the Jaynes-Cummings model. The results reveal novel quantum phenomena arising from multipartite couplings and suggest a pathway toward richer hybrid quantum information processing using three-body interactions.

Abstract

Three-body interactions are fundamental for realizing novel quantum phenomena beyond pairwise physics, yet their implementation -- particularly among distinct quantum systems -- remains challenging. Here, we propose a hybrid quantum architecture comprising a magnonic mode (in a YIG sphere), an Andreev spin qubit (ASQ), and a superconducting qubit (SCQ), to realize a strong three-body interaction at the single-quantum level. Leveraging the spin-dependent supercurrent and circuit-integration flexibility of the ASQ, it is possible to engineer a strong tripartite coupling that jointly excites both qubits upon magnon annihilation (or excites magnons and SCQs upon ASQ deexcitation). Through analytical and numerical studies, we demonstrate that this interaction induces synchronized collapse and revival in qubit populations when the magnon is initially prepared in a coherent state. Notably, during the collapse region -- where populations remain static -- the entanglement structure undergoes a dramatic and continuous reorganization. We show that the genuine tripartite entanglement is redistributed into bipartite entanglement between the two qubits, and vice versa, with the total entanglement conserved. These phenomena, unattainable via two-body couplings, underscore the potential of three-body interactions for exploring intrinsically new quantum effects and advancing hybrid quantum information platforms.

Figures (12)

• Figure 1: The hybrid quantum system consisting of the magnon, ASQ from the quantum dot junction, and the SCQ from the SQUID and capacitor.
• Figure 2: (a) Variation of the coupling strengths $G$ with the external flux $\Phi_\mathrm{ext}$ for different asymmetry $a$. (b) Contour maps of the coupling strengths $G$ versus the ratio $E_{J}^{\mathrm{sum}}/E_C$ and spin-dependent energy $E_\text{SO}$ with $a=0.1$. (c) The three-body interaction induce dynamical evolution under the resonance condition $\omega_m=\omega_a+\omega_s$. In the upper panel, the dissipation rates are chosen as those in the main text. In the lower panel, the dissipation rates are reduced as $\kappa_m/2\pi=0.1~\mathrm{MHz}$ and $\gamma_a/2\pi=0.1~\mathrm{MHz}$.
• Figure 3: (a) Simulated evolution of populations without decoherence. The shaded region denotes the collapse region. (b) and (c) shows the evolution of the bipartite entanglement and the residual entanglements with time. (d) schematic diagram of entanglement redistribution.
• Figure 4: (a) Illustration of a semiconductor (silver) with epitaxial superconducting leads (light blue). (b) Conceptual diagram of cooper pair tunneling between semiconducting quantum dot and superconductors. Black and gradient color denote the spin-conserving and spin-flipping tunnel, respectively. (c) Plot of the frequency of the ASQ as functions of the external magnetic field $B_Z$. The angle and phase difference are $\theta=\pi/2$ and $\varphi_1=\pi/2$.
• Figure 5: (a) Superconducting circuit model of capacitor, and the SQUID consisting of the quantum dot junction and the conventional Josephson. (b) The frequency $\omega_S$ of the SCQ versus the external flux $\Phi_\mathrm{ext}$ for different junction asymmetry $a$. The relevant parameters are selected as $E_C/h=200\mathrm{MHz}$ and $E_J^\mathrm{sum}/h=10\mathrm{GHz}$