Photon-Phonon Lattice Achieves Coherent Perfect Absorption in New Design

Researchers from the University of Science and Technology of China, Shanxi University, Peking University, and Beijing Academy of Quantum Information Sciences have demonstrated coherent perfect absorption within a newly designed synthetic photon-phonon lattice. This work details a method for achieving complete absorption of light, a phenomenon typically limited by narrow bandwidths and thermal noise, by harnessing collective interference between light and mechanical vibrations. By utilizing cavity-reservoir-mediated interactions, the team shifted the conditions for coherent perfect absorption into a high-cooperativity regime, enabling both absorption and ground-state cooling of the mechanical oscillator. The results identify collective interference as a route to quantum-compatible perfect absorption and long-lived quantum storage, potentially advancing optical control and quantum technologies.

Coherent Perfect Absorption Across Physical Platforms A meticulously engineered structure has enabled researchers to achieve coherent perfect absorption, defying conventional limitations of optomechanical systems. This breakthrough, detailed in a recent publication, moves beyond simply absorbing light; it demonstrates control over the way light is absorbed, maintaining its wave-like properties during the process, a critical step toward advanced optical technologies.

The team’s approach centers on a novel material structure, a synthetic photon-phonon lattice, created through time-dependent optomechanical couplings. Unlike previous optomechanical CPA experiments restricted to weak-cooperativity regimes, this design leverages long-range interactions and cooperative interference among multiple synthetic lattice sites, mediated by the shared reservoir. This allows for a shift of the CPA condition deep into the high-cooperativity regime, a significant advancement. The researchers, from the University of Science and Technology of China, Shanxi University, Peking University, and Beijing Academy of Quantum Information Sciences, constructed this lattice by applying two pump tones with a small frequency offset, resulting in a time-dependent interaction Hamiltonian. This manipulation effectively creates a bipartite structure in synthetic frequency space, interleaving photonic and phononic Floquet sidebands. The paper states that the resulting time-dependent interaction Hamiltonian takes a specific form, outlining the mathematical foundation of their design. Crucially, this configuration allows for ground-state cooling of the mechanical oscillator, simultaneously broadening the absorption lineshape and generating a singular group-delay response. Measurements revealed a group delay of up to 1.4 picoseconds, accompanied by a non-Lorentzian absorption profile exhibiting a broadening of three orders of magnitude beyond the intrinsic mechanical linewidth. The authors report that as a consequence, they uncovered a group-delay divergence singularity accompanying C-CPA and achieved a group delay of up to 1.4 ps, while the mechanical oscillator entered its ground state. This enhanced performance is attributed to collective interference, shifting the CPA condition into a regime where thermal noise is minimized.

The team demonstrated that the reflection coefficient is governed by the coherent superposition of contributions from all lattice sites within the input, output formalism, highlighting the importance of collective behavior. The implications of this research extend beyond fundamental physics. By operating in the quantum regime of mechanical motion, the team has established a pathway toward thermal-noise-free and long-lived on-chip optomechanical quantum storage. This advancement could prove vital for developing more robust and efficient quantum information processing systems, offering a promising route toward practical quantum technologies.

Floquet Lattice Design for Photon-Phonon Interactions The pursuit of controlling light and sound at the quantum level has led researchers to increasingly complex material designs, moving beyond simple optical cavities to engineered structures that dictate how photons and phonons, quanta of light and sound, interact. Recent work from a collaboration involving the University of Science and Technology of China, Shanxi University, Beijing Academy of Quantum Information Sciences, and Peking University details a novel approach: the creation of a structure where time-dependent optomechanical couplings orchestrate interactions. This isn’t a physically grown crystal lattice, but one fabricated through precisely timed laser pulses, offering unprecedented control over light-matter interactions. Central to this advance is the demonstration of collective coherent perfect absorption (C-CPA), a phenomenon where incoming light is completely absorbed through constructive interference. While CPA has been observed in various systems, achieving it within a high-cooperativity regime, meaning strong coupling between light and mechanical motion, has remained a significant challenge. The core innovation lies in moving beyond the limitations of traditional optomechanical CPA, which is confined to weak-cooperativity regimes where thermal noise dominates. This manipulation allows for a level of control previously unattainable, enabling the system to operate deep into the high-cooperativity regime. The resulting configuration isn’t just about stronger interactions; it’s about achieving ground-state cooling of the mechanical oscillator. Crucially, this advancement allows for a broadened absorption bandwidth, exceeding the intrinsic mechanical linewidth by a broadening of three orders of magnitude. This allows for energy redistribution across the entire lattice leading to the observed collective interference effects and ultimately, the realization of high-cooperativity CPA. Researchers have achieved coherent perfect absorption (CPA), the complete absorption of a coherent light wave, not under restrictive conditions, but within a specially engineered structure opening doors to quantum-compatible optical storage. This lattice, constructed from light and mechanical vibrations, leverages collective interference to dramatically alter how light interacts with the material.

The team’s innovation centers on manipulating optomechanical interactions using two precisely tuned pump tones. This approach results in a synthetic frequency lattice, where photonic and phononic Floquet sidebands form interconnected sublattices. This isn’t simply a static structure; the time-dependent modulation creates a dynamic environment for light and sound, enabling control over their interaction. The researchers also observed a striking effect on the speed of light within the material, reporting a substantial increase compared to traditional optomechanical systems. This manipulation of group delay, the speed at which the envelope of a wave travels, is critical for potential applications in optical buffering and quantum memory. Optomechanical Systems & Quantum Storage Potential The pursuit of stable quantum storage has long focused on atomic systems and trapped ions, yet a surprising contender is emerging: meticulously engineered mechanical vibrations. While seemingly counterintuitive, harnessing macroscopic motion for quantum effects, recent work demonstrates a pathway toward realizing long-lived quantum memories within optomechanical systems, defying limitations previously thought insurmountable. Central to this advancement is the creation of a structure, not naturally occurring, but deliberately constructed through time-dependent optomechanical couplings. Traditional optomechanical CPA suffered from a narrow absorption bandwidth and a mechanically excited state, hindering its potential as a quantum memory. This new configuration enables CPA to coexist with ground-state cooling of the mechanical oscillator, dramatically reducing thermal noise. Measurements revealed a broadened, non-Lorentzian absorption lineshape, expanding the bandwidth by three orders of magnitude. The researchers found that the effective phonon number could be driven into the ground state regime. This breakthrough isn’t simply about achieving CPA; it’s about extending the operating regime into the quantum domain. This work represents a significant step toward realizing robust and scalable quantum information processing using integrated optomechanical devices, potentially offering a complementary approach to existing quantum technologies. 👉 More information🗞 Collective Coherent Perfect Absorption in a Synthetic Photon-Phonon Lattice✍️ Sihan Wang, Qichun Liu, Bo Song, Qiongyi He, Jingwei Zhou and Yulong Liu🧠 ArXiv: https://arxiv.org/abs/2607.18902 Stay currentSee today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals. Tags: