Bin Luo1,Andreas Winkler2,Hagen Schmidt2,Benyamin Davaji1,Derek Bas3,Michael McConney3,Michael Page3,Beaver Nathaniel1,Paul Stevenson1,Nian Sun1
Northeastern University1,Leibniz Institute for Solid State and Materials Research2,Air Force Research Laboratory3
Bin Luo1,Andreas Winkler2,Hagen Schmidt2,Benyamin Davaji1,Derek Bas3,Michael McConney3,Michael Page3,Beaver Nathaniel1,Paul Stevenson1,Nian Sun1
Northeastern University1,Leibniz Institute for Solid State and Materials Research2,Air Force Research Laboratory3
<b>Motivation</b><br/>Owing to long coherence time, high fidelity and easy optical initiation and readout of quantum states tuned by magnetic excitations over a broad temperature range, NV<sup>−</sup> centers are intriguing solid-state platforms for quantum computing, communication, information processing and sensitive non-invasive nanoscale magnetic sensors. The SAW delay line driven spin wave enabled by magnon-phonon interactions exhibits superior properties of high-power efficiency, low noise and small footprint, leading to efficient voltage control of NV<sup>−</sup> center and quantum transduction between hybrid quantum systems. In this work, we present a 2D finite element (FEM) model for a fabricated SAW delay line with S11 minima at 2.87 GHz and ~ −10 dB insertion loss for NV center excitation. The consistency of S parameters between simulation and probing experiments makes the model prospective for SAW delay line design for chemical, biomedical, RF and quantum applications.<br/><br/><b>Methods</b><br/>The transmission and receiving IDT Al electrodes with a fundamental mode of ~2.87 GHz were patterned on bulk LiNbO<sub>3</sub> substrate via laser lithography, e-beam lithography, e-beam metal evaporation and lift-off technique. The S parameters were measured by RF probes connected to a vector network analyzer. A 1:1 2D finite element model was built in COMSOL Multiphysics. The electrostatic module was combined with solid mechanics module to simulate piezoelectrically induced Rayleigh wave excited by SAW delay line under different attenuation conditions.<br/><br/><b>Results</b><br/>The fabricated SAW delay line shows a low insertion loss of ~ −10 dB at 2.87 GHz, which is excellent to control the ground states of NV<sup>−</sup> centers. The simulated S parameters agree well with probe measurement. The displacement and electric field profile demonstrate a high transmission between IDT electrodes. The increased mechanical damping results in decreased Sxy magnitude and diminished modulation of the SAW resonance peak ("triple transit echo") caused by reflections between the IDTs near fundamental mode.