Collective Coherent Perfect Absorption in a Synthetic Photon-Phonon Lattice

Traditional optomechanical coherent perfect absorption (OM-CPA) is fundamentally limited to the weak-cooperativity regime, which restricts its bandwidth and prevents the mechanical oscillator from reaching its quantum ground state. This paper investigates whether collective interference in a synthetic photon-phonon lattice can overcome these constraints to enable quantum-compatible perfect absorption.

To achieve this, the researchers engineered a synthetic frequency lattice using time-dependent optomechanical couplings. By applying two pump tones with a specific frequency offset, they created a Floquet-engineered system where photonic and phononic sidebands form a bipartite Wannier-Stark lattice. This setup allows for long-range interactions and cooperative interference among multiple lattice sites, mediated by a shared cavity reservoir. The experiment was conducted using a superconducting microwave resonator coupled to a silicon carbide membrane at 10 mK.

• High-Cooperativity CPA: The collective interference mechanism shifts the CPA condition into the high-cooperativity regime (C > 1000), allowing the system to operate while the mechanical oscillator is in its ground state.
• Enhanced Bandwidth: The absorption profile is non-Lorentzian and significantly broader than the intrinsic mechanical linewidth, with the bandwidth tunable by the modulation frequency.
• Singular Group Delay: The system exhibits a phase singularity at the CPA point, resulting in group delays on the order of 10 seconds, which can be tuned between slow-light and fast-light regimes.
• Quantum Compatibility: By operating at high cooperativity, the system successfully suppresses thermal occupation, providing a viable platform for thermal-noise-free quantum storage.

This work provides a robust pathway for integrating optomechanical systems into quantum information processing. By decoupling the absorption bandwidth from mechanical dissipation and enabling ground-state operation, this approach overcomes the primary limitations of previous OM-CPA designs. It offers a versatile, tunable platform for applications in long-lived quantum memory, reconfigurable slow/fast light, and broader explorations of many-body dynamics in synthetic dimensions.