RUI: Coupling Trapped Ions to Bulk Piezoelectric Resonators

Middlebury College, Middlebury VT

Investigators

Abstract

Individual atomic ions, isolated in evacuated metal chambers where they can be confined and levitated by electric forces, are a key component of newly developing quantum technologies for communication, sensing, and computation. In most cases these atoms are controlled by laser light directed through the chamber’s windows and are monitored by detecting the light the atoms emit. When the atomic ions are brought close to solid surfaces, they can exhibit new behavior that could remove the need for the lasers, allowing quantum control to be performed entirely electronically, which could vastly simplify experimental setups. The PI and his undergraduate research students will study the interactions of a single trapped atomic ion with a nearby vibrating piezoelectric crystal (piezo). This type of material is commonly used in sensors to measure small forces or displacements by converting them directly into electrical signals. This application could be enhanced by quantum sensing techniques applied to a nearby trapped ion if the ion-piezo interactions were well understood. The research group will measure the dependence of the interaction on several parameters, including the distance between the ions and the crystal, and the vibrational frequency of the levitated trapped ion, and will compare the results to a theoretical model. Good agreement between experiment and theory will motivate follow-up experiments seeking to control the ions with the crystal and eventually to design and construct quantum enhanced piezo sensors. Much of the experiment, from apparatus design and building to data acquisition and analysis, will be performed by undergraduate students, helping them develop skills necessary for graduate studies and careers in the burgeoning field of quantum information science and technology. The PI will experimentally measure the effects of a bulk piezoelectric resonator coupling to the motion of trapped atomic ions. The experiment will consist of a singly ionized Ytterbium (Yb) atom, stably confined by a radiofrequency (RF) ion trap, placed in proximity to a bulk lead zirconate titanate piezoelectric resonator (piezo) within an ultra-high vacuum chamber. With the piezo at room temperature, the coupling should manifest itself as an increased heating rate of the ion’s motion when on resonance with the piezo's mechanical vibrations. By performing thermometry measurements on the trapped ion, the research team can infer the strength of this coupling as a function of piezo-ion distance by moving the piezo on an in-vacuum translation stage. Crystals of trapped atomic Yb ions have proven to be an ideal platform for engineering complex quantum systems, where the Coulomb repulsion between ions can be used to generate entanglement within a crystal using coherent laser interactions. However, this approach has fundamental limitations when attempting to scale the ion numbers past current limits; a problem which a controlled piezo-ion coupling could help solve. For instance, a piezo could be built into an optomechanical cavity to form a quantum transducer, imprinting information about the ion's motion into the frequency modulation of a laser beam and making it available for long-distance transmission. In addition, piezoelectric materials see wide use as mechanical sensors, and the ability to couple a piezo and ion crystal could lead to development of enhanced quantum sensing techniques for piezo readout. The piezo again serves as a transducer, transforming mechanical vibrations into electrical vibrations to which trapped ions are exquisitely sensitive. This project is jointly funded by the AMO Experimental Physics Program and the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.