Curator's Take
This article presents a significant advance in generating large optical coherent-state superpositions - the quantum equivalent of Schrödinger's cat states made of light - using a deterministic approach that could be more practical than existing probabilistic methods. The researchers demonstrate that their cavity QED-based protocol outperforms current state-of-the-art techniques, which is particularly exciting because these "cat states" are crucial building blocks for quantum sensing applications that could detect incredibly weak signals and for error-corrected quantum computing architectures. What makes this work especially promising is its deterministic nature and compatibility with existing cavity QED platforms, potentially making these exotic quantum states more accessible for real-world applications in quantum sensors and quantum communication networks. The proposed interference fringe measurements also offer a practical way to verify these delicate quantum superpositions, addressing a key challenge in the field.
— Mark Eatherly
Summary
Large optical coherent-state superpositions are essential to advance quantum sensing, quantum repeaters and error-correction codes. We propose a deterministic feedforward protocol employing qubit-mode dispersive coupling, currently available in cavity quantum electrodynamics (QED). We show this single-mode protocol to outperform the advanced three-mode Gaussian-photon-number-resolving detector scheme both in terms of average fidelity and quantum non-Gaussian phase-space properties, and propose sensitivity to weak displacements of interference fringes as a feasible and conclusive witness of quantum interference. This approach combining QED with electro-optical feedforward is extendable to tailored states for applications and other platforms.