N-Cavity-Magnon Polariton Blockade via Kerr Nonlinearity

Abstract

We theoretically propose a scheme to realize a $n$-cavity-magnon polariton blockade in a cavity-magnon system by utilizing the Kerr nonlinearity. Cavity-magnon polaritons are hybrid quasiparticles formed by the strong coupling between cavity photons and magnons. The Kerr nonlinearity introduces anharmonicity into the polariton energy spectrum, which in turn enables the blockade effect. We demonstrate that when the external driving frequency is resonant with the transition to the $n$th polariton excited state, a perfect $n$-polariton blockade is achieved. Moreover, increasing the driving strength enhances higher-order blockade while maintaining high purity. Our work pioneers the field of cavity-magnon polariton blockade, opens a new avenue for the preparation of controllable quantum resources and holds significant potential for applications in the fields of quantum communication and quantum information processing.

Figures (5)

• Figure 1: (a) Sketch of the system. (b)Schematic of the $p_+$ polariton energy levels. Here, $\omega_d^{(n)}$ ($n=1, 2, 3$) denotes the external driving frequency required to induce the $n$CMPB, and it satisfies the condition given in Eq. (\ref{['eq5']}).
• Figure 2: Time evolution of the excitation number distribution for the (a) $n$ = 2 and (c) $n$ = 3 cases. $P_{j}= \langle \psi(t)|j \rangle \langle j | \psi(t) \rangle$ ($j=0,1,2,3,4$). Here, $|j \rangle \langle j|$ is the projection operator onto the $j$-th Fock state of the $p_+$ mode. Time evolution of the mean excitation number for the (b) $n$ = 2 and (d) $n$ = 3. The average particle number $\langle p_{+}^{\dagger} p_{+} \rangle = \langle \psi(t) |p_{+}^{\dagger} p_{+}| \psi(t) \rangle$. $\Delta_+/g = -0.025$ in panels (a) and (b) and $\Delta_+/g = -0.0375$ in panels (c) and (d). System parameters are $K/g=0.05$, and $\Omega/g=G/g=0.005$.
• Figure 3: Fidelity $F_p(n)$ as a function of $\Omega/K$ for the cases of (a) $n$ = 2 and (b) $n$ = 3. $\Delta_+/g =-0.025$ in panel (a) and $\Delta_+/g = -0.0375$ in panel (b). System parameters are $K/g=0.05$ and $G/g=0.005$.
• Figure 4: Excitation number probability distribution, and mean excitation number as a function of the detuning, $\Delta_+/g$, in the steady state $\rho_{ss}$. $P_{j}= \mathrm{Tr}(| j \rangle \langle j|\rho_{ss})$ ($j=0,1,2,3,4$). $\langle p_{+}^{\dagger} p_{+} \rangle = \mathrm{Tr}(p_{+}^{\dagger} p_{+}\rho_{ss})$. $G/g=0.005$ in panels (a) and (b) and $G/g=0.01$ in panels (c) and (d). The gray dashed lines in the figure (from right to left) indicate the theoretical conditions for the $n$PB for $n$ = 2, 3, 4, and 5, respectively. System parameters are $K/g=0.05$, $\Omega/g=0.01$ and $\kappa/g=0.001$.
• Figure 5: Fidelities $F_p(n)$ and the mean excitation number as a function of the drive strength (a) $G$ and (b) $\Omega$ for different $n$CMPB conditions. System parameters are $K/g=0.05$ and $\kappa/g=0.001$.