Robust photon blockade with hybrid molecular optomechanics

Abstract

Molecular cavity optomechanical systems, featuring ultrahigh vibrational frequencies and strong light-matter interactions, hold significant promise for advancing applications in quantum science and technology. Specifically, by introducing metallic nanoparticles into microcavities, hybrid molecular cavity optomechanical systems can further enhance optical quality factors and system tunabilities, which enables scalable and controllable quantum platforms. In this study, we propose how to realize robust photon blockade, i.e., strong photon antibunching with arbitrary detuning conditions, by combining degenerate optical parametric amplification with a hybrid molecular cavity optomechanical system. More interesting, we find near-perfect optomechanical photon blockade at room temperature, which is robust against temperature and optical dissipation. In addition, our approach can release the strict condition of high temporal resolution by combining features of conventional and unconventional photon blockade. Our approach offers a feasible route to study intriguing quantum effects in hybrid molecular cavity optomechanical systems, and holds promise for applications in nonclassical state engineering, quantum sensing, and photonic precision measurements.

Figures (4)

• Figure 1: Parametric amplification assistant hybrid molecule cavity optomechanical system.a Schematic of the hybrid molecule cavity optomechanical system. A plasmonic nanocavity, formed by metallic nanoparticles and molecules deposited on a Fabry-Pérot (FP) cavity, is driven by an external laser of frequency $\omega_{L}$. A degenerate optical parametric amplifier (OPA) inside the Fabry-Pérot cavity is driven by a laser of amplitude $\Omega$ and frequency $\omega_{d}$. The inset shows the nanoparticle-on-mirror (NPoM) structure of the plasmonic nanocavity, where molecules is situated in the nanogap. b Schematic diagram of the equivalent mode-coupling model. The plasmonic nanocavity mode is coupled to the molecular vibrational (acoustic) mode via radiation pressure. This mode is also coupled to the Fabry-Pérot cavity mode (incorporating the parametric process) through evanescent fields interactions.
• Figure 2: The mechanism and optimal parametric gain conditions of molecular optomechanical photon blockade. a The destructive interference of the three transition from state $|0,0\rangle$ to state $|2,0\rangle$ (red, blue, green arrows) prevents two-photon occupation, enabling the unconventional photon blockade effect. b Second-order correlation $g^{(2)}(0)$ as a function versus detuning $\Delta$ and parametric gain amplitude $\Omega$. c Quantum correlation $g^{(2)}(0)$ as a function versus of detuning $\Delta$ and parametric gain phase $\theta$. Here, $P_\mathrm{in} = 0.1\,\mathrm{nW}$, $T=0 \mathrm{K}$. The other parameters are given in the main text.
• Figure 3: Robustness of the molecular optomechanical photon blockade against varying temperature and cavity quality factor.a The second-order correlation function $g^{(2)}(0)$ versus $T$ at driving power $P_\mathrm{in} = 0.1\,\mathrm{nW}$ and $\Delta/2\pi = 0\,\mathrm{THz}$, showing that $g^{(2)}(0) \ll 1$ under room-temperature conditions, thereby demonstrating robust photon blockade in the presence of thermal effects. b Influence of the cavity quality factor $Q$ on unconventional photon blockade at an input power of $P_\mathrm{in} = 0.1\,\mathrm{nW}$. Across a broad range of $Q$ values, perfect unconventional photon blockade can be achieved by properly tuning the $\Omega$, and the optimal $\Omega$ is consistent in the high-$Q$ regime. c For $\Omega/2\pi = 38.4\,\mathrm{MHz}$, $g^{(2)}(0)$ remains effectively insensitive to $Q$ for $Q > 10^{5}$, demonstrating the minimal impact of the cavity quality factor on unconventional photon blockade under these conditions. The other parameters are the same as those in Fig. \ref{['Fig2']}.
• Figure 4: Robust and oscillation-free photon blockade over time. For a$\Delta/2\pi = -10\,\mathrm{THz}$, b$\Delta/2\pi = -5\,\mathrm{THz}$ and c$\Delta/2\pi = 0\,\mathrm{THz}$, the optimal parametric gain amplitude for realizing robust photon blockade is $\Omega/2\pi = 2.1\,\mathrm{MHz}$, $\Omega/2\pi = 11.5\,\mathrm{MHz}$ and $\Omega/2\pi = 38.4\,\mathrm{MHz}$, respectively. d, e, f The evolution of the second-order correlation function $g^{(2)}(\tau)$ with respect to the time delay $\tau/\gamma$, showing no oscillations at $\Delta = 0$, thereby indicating that high temporal resolution is not needed to observe photon blockade in this regime. Here, $P_\mathrm{in} = 0.1\,\mathrm{nW}$, and the other parameters are the same as those in Fig. \ref{['Fig2']}.