Researchers from the University of Rochester have utilized surface acoustic waves to address a significant obstacle in the creation of a quantum internet.
In a recent publication featured in Nature Communications, scholars from Rochester’s Institute of Optics and Department of Physics and Astronomy outline a method for pairing photons and phonons that may be used to accurately transfer data stored within quantum systems—qubits—to optical fields, which can be transmitted over great distances.
What are surface acoustic waves?
Surface acoustic waves are oscillations that travel along the surface of materials similar to waves in the ocean or vibrations felt during an earthquake. They have numerous applications—many electronic components in our smartphones utilize surface acoustic wave filters—because they create highly precise cavities that can be deployed for accurate timing in applications such as navigation. However, researchers have begun to apply them in quantum contexts as well.
Utilizing current techniques, surface acoustic waves are accessed, adjusted, and directed through piezoelectric materials which convert electricity into acoustic waves and vice versa. However, these electrical signals must be input into mechanical fingers located within the center of the acoustic cavity, leading to interference from scattered phonons that must be mitigated.
Employing light to control surface acoustic waves
Instead of linking the phonons to electric fields, Renninger’s laboratory adopted a less invasive method, illuminating the cavities with light and removing the necessity for mechanical contact.
“We successfully achieved strong coupling between surface acoustic waves and light,” states Arjun Iyer, a PhD student in optics and lead author of the study. “We developed acoustic cavities, or tiny echo chambers, for these waves where sound could persist for an extended period, facilitating stronger interactions. Remarkably, our approach is applicable to any material, not just the piezoelectric ones amenable to electrical control.”
Renninger’s team collaborated with Associate Professor of Physics John Nichol’s lab to fabricate the surface acoustic wave devices highlighted in the research. Apart from enabling robust quantum coupling, these devices are characterized by easy fabrication, compact size, and the capability to manage large amounts of power.
In addition to their role in hybrid quantum computing, the group asserts their methods can also serve in spectroscopy to investigate material properties, as sensors, and for studying condensed matter physics.
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