Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences and the OxideMEMS Lab at Purdue University have developed a system that uses atomic vacancies in silicon carbide to measure the stability and quality of acoustic resonators. These resonators are used in most smart phones, Wi-Fi and GPS systems to filter out noise that could degrade a signal. The researchers’ system could also be used for acoustically-controlled quantum information processing, providing a new way to manipulate quantum states embedded in silicon carbide. This technique could be used in monitoring the performance of accelerometers, gyroscopes and clocks over their lifetime and has potential for hybrid quantum memories and quantum networking.
Introduction
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences and the OxideMEMS Lab at Purdue University have developed a system to measure the stability and quality of acoustic resonators, commonly used in smartphones and GPS systems. The system uses atomic vacancies in silicon carbide, a common semiconductor, to monitor the performance of these devices. The technique could also be used for acoustically-controlled quantum information processing, offering a new way to manipulate quantum states. The research, led by Evelyn Hu and Sunil Bhave, was published in Nature Electronics.
Acoustic Resonators and Their Stability
Acoustic resonators are commonly used in smartphones and other devices such as Wi-Fi and GPS systems as radio frequency filters to filter out noise that could degrade a signal. These resonators are more stable than their electrical counterparts, but they can degrade over time. Currently, there is no simple method to actively monitor and analyse the degradation of the material quality of these widely used devices.
New System to Measure Stability of Acoustic Resonators
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with researchers at the OxideMEMS Lab at Purdue University, have developed a system that uses atomic vacancies in silicon carbide to measure the stability and quality of acoustic resonators. Silicon carbide is a readily available commercial semiconductor used at room temperature. This technique in silicon carbide could be used in monitoring the performance of accelerometers, gyroscopes and clocks over their lifetime.
Acoustic Resonators and Quantum Information Processing
The atomic vacancies in silicon carbide used to measure the stability and quality of acoustic resonators could also be used for acoustically controlled quantum information processing. This provides a new way to manipulate quantum states embedded in this commonly-used material. This has potential for hybrid quantum memories and quantum networking.
Inside Acoustic Resonators
Silicon carbide is a common material for microelectromechanical systems (MEMS), which includes bulk acoustic resonators. However, crystal growth defects such as dislocations and grain boundaries as well as resonator manufacturing defects such as roughness, tether stress, and micro-scale craters can cause stress-concentrations regions inside the MEMS resonator. Currently, the only way to see what’s happening inside an acoustic resonator without destroying it is with super powerful and very expensive x-rays.
Acoustic Control in Quantum Systems
The same defects in silicon carbide that are used to measure the stability and quality of acoustic resonators can also be qubits within a quantum system. Many quantum technologies build on the coherence of spins: how long spins will remain in a particular state. That coherence is often controlled with a magnetic field. However, the researchers demonstrated that they could control spin by mechanically deforming the material with acoustic waves, obtaining a quality of control similar to other approaches using alternating magnetic fields. This provides an important new handle on an intrinsic property of a material that can be used to control the quantum state embedded within that material.
“Silicon carbide, which is the host for both the quantum reporters and the acoustic resonator probe, is a readily available commercial semiconductor that can be used at room temperature,” said Evelyn Hu, the Tarr-Coyne Professor of Applied Physics and of Electrical Engineering and the Robin Li and Melissa Ma Professor of Arts and Sciences, and senior author of the paper. “As an acoustic resonator probe, this technique in silicon carbide could be used in monitoring the performance of accelerometers, gyroscopes and clocks over their lifetime and, in a quantum scheme, has potential for hybrid quantum memories and quantum networking.”
“Wafer-scale manufacturable silicon carbide resonators in particular are known to have the best-in-class performance for quality factor,” said Sunil Bhave, professor at the Elmore Family School of Electrical and Computer Engineering at Purdue and co-author of the paper. “But crystal growth defects such as dislocations and grain boundaries as well as resonator manufacturing defects such as roughness, tether stress, and micro-scale craters can cause stress-concentrations regions inside the MEMS resonator.”
“These types of expensive and difficult-to-access machines are not deployable for doing measurements or characterization in a foundry or somewhere where you’d actually be making or deploying these devices,” said Jonathan Dietz, graduate student at SEAS and co-first author of the paper. “Our motivation was to try to develop an approach that would allow us to monitor the acoustic energy inside of a bulk acoustic resonator so you can then take those results and feed them back into the design and fabrication process.”
“How dim or how bright the light indicates how strong the acoustic energy is in the local environment where the defect is,” said Aaron Day, a graduate student at SEAS and co-author of the paper. “Because these defects are the size of single atoms, the information they give you is very local and, as a result, you can actually map out the acoustic waves inside the device in this non-destructive way.”
“To use the natural mechanical properties of a material — its strain — expands the range of material control that we have,” said Hu. “When we deform the material, we find that we can also control the coherence of spin and we can get that information just by launching an acoustic wave through the material. It provides an important new handle on an intrinsic property of a material that we can use to control the quantum state embedded within that material.”
Summary
Researchers at Harvard and Purdue University have developed a system using atomic vacancies in silicon carbide to measure the stability and quality of acoustic resonators, commonly used in smartphones and GPS systems. This technique could also be used for acoustically-controlled quantum information processing, offering a new way to manipulate quantum states in this widely-used material.
- Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the OxideMEMS Lab at Purdue University have developed a system to measure the stability and quality of acoustic resonators.
- The system uses atomic vacancies in silicon carbide, a common material for microelectromechanical systems (MEMS), which includes bulk acoustic resonators.
- The vacancies could also be used for acoustically-controlled quantum information processing, providing a new way to manipulate quantum states embedded in this commonly-used material.
- The technique could be used in monitoring the performance of accelerometers, gyroscopes and clocks over their lifetime and has potential for hybrid quantum memories and quantum networking, according to Evelyn Hu, a professor at SEAS.
- The only current way to see what’s happening inside an acoustic resonator without destroying it is with expensive x-rays, such as the broad-spectral x-ray beam at the Argonne National Lab.
- The new approach allows for monitoring the acoustic energy inside of a bulk acoustic resonator in a non-destructive way, which can then be used to improve the design and fabrication process.
- The research was published in Nature Electronics and was supported by the National Science Foundation.
