Engineered Light and Motion Creates Controllable Quantum Link for Communication Technologies.

The manipulation of quantum entanglement represents a crucial area of research for advancements in quantum technologies. Zeng, Liu, and Guo investigate a novel electro-optomechanical system – a hybrid device integrating electrical, optical, and mechanical components – to achieve both strong quantum squeezing and perfect one-way Einstein-Podolsky-Rosen (EPR) steering. EPR steering, a form of entanglement, allows one party to remotely ‘steer’ the quantum state of another, differing from standard entanglement in the asymmetry of control. Their research demonstrates that, through precise control of microwave and optical driving fields within the system, significant squeezing – a reduction in quantum noise – can be achieved in both the microwave and mechanical components. Furthermore, they show that this system facilitates perfect one-way EPR steering between the optical cavity and the mechanical oscillator, with the degree of steering controllable via external driving parameters, and exhibits resilience to temperature fluctuations. This configuration presents a potential architecture for future quantum information processing and microwave communication technologies.

This work demonstrates the potential of a three-mode electro-optomechanical system to simultaneously generate strong squeezing in both the microwave field of an LC circuit and the mechanical mode, alongside perfect one-way Einstein-Podolsky-Rosen (EPR) steering between the optical cavity and the mechanical oscillator. By employing dual-tone driving of the optical cavity and microwave driving of the LC circuit, the system achieves these non-classical states without modification to its core components. The degree of one-way EPR steering is demonstrably controllable through manipulation of the driving light.

The system functions by leveraging the mechanical oscillator as an intermediary, enabling transduction between optical and microwave frequencies. The mechanical displacement, induced by radiation pressure within the optical cavity, modulates the capacitance of the LC circuit, thereby coupling the microwave field to both the mechanical and electromagnetic fields. This interconnectedness allows for the preparation of entangled states and the manipulation of quantum states across different frequency bands.

By employing dual-light-driven optical cavities with differing frequencies and amplitudes, they transferred mechanical squeezing to the microwave mode. A red-detuned drive on the LC circuit was crucial for this transfer, enabling the preparation of strongly squeezed states in both the microwave field and the mechanical mode. This approach distinguishes itself from previous methods that often rely on complex system modifications or specific detuning schemes.

The robustness of the observed squeezing and EPR steering against environmental temperature further enhances the practical viability of this system. This configuration offers a promising platform for advancements in quantum information processing and, specifically, microwave quantum communication, where the ability to generate and control non-classical states is paramount.

Future research could focus on exploring the system’s capabilities for more complex quantum protocols, such as quantum key distribution or quantum teleportation. Investigating the impact of different system parameters, including cavity and circuit impedances, on the efficiency of state transfer and entanglement generation would also be valuable. Furthermore, extending the model to incorporate additional degrees of freedom or exploring alternative driving schemes could unlock even more sophisticated functionalities within this versatile electro-optomechanical framework.