Meghna Madhusudan and Susmita Dey Manasi Receive Cadence Technology Awards

Doctoral students Meghna Madhusudan  (advisor Professor Ramesh Harjani) and Susmita Dey Manasi (advisor Professor Sachin Sapatnekar) are recipients of Cadence’s Women in Technology scholarships for 2020-2021. These scholarships are awarded as part of Cadence’s mission to foster inclusion and diversity in technology programs and careers.

MEGHNA’S RESEARCH

Meghna’s research interest lies in electronic design automation (EDA) of analog circuits, which are found in diverse applications ranging from cell phones to biomedical devices. Current industry practice involves an individual designing these circuits, and the process can take weeks or even months, and demands high levels of expertise. The time intensive nature of circuit design often causes bottlenecks in the chip design process, and raises costs. Ongoing research in analog EDA seeks to automate circuit design to speed it up, and require minimal human intervention.

Meghna is currently engaged with ALIGN (Analog Layout Intelligently Generated from Netlists), a DARPA-funded project (under its Electronics Resurgence Initiative) led by Professor Sapatnekar with Professor Harjani as collaborator. ALIGN is working on automating a complex and sensitive part of the design process: constructing the layout of devices as they will appear on the chip. These layouts are critical to the successful functioning of a circuit. A collaborative endeavor comprising University of Minnesota, Texas A&M University, and Intel, ALIGN will build software that can understand and build specific layouts in a matter of minutes. (Eventually, ALIGN aims to automatically generate analog layouts for most analog circuits in less than 24 hours.) Contrast this to a manually undertaken design process which can take several days or even weeks. However, one of the challenges of analog EDA is building robust solutions for automating a variety of analog circuits. Meghna addresses this particular challenge. Her work involves splitting an analog circuit into common circuit structures that are typically found across a variety of different types of analog circuits, and framing the automation methodology to build these common structures in the best possible way.

IMPLICATIONS OF MEGHNA’S RESEARCH

Successful implementation will result in significant savings in time while retaining high levels of accuracy. Automation of the design of analog circuits releases the bottleneck in the chip design process, while opening up the opportunity to explore and utilize the design space more efficiently. The outcome is improved circuit performance when compared to a manual chip design process.

Another significant outcome that Meghna hopes to achieve is industry wide acceptance of analog EDA. For many years, designers in the industry have been sceptical of the tools built by EDA researchers due to issues such as predictability and control. But Meghna hopes that with her use of the building block method, an approach similar to what is used in the manual design process prevalent in the industry, she can overcome current reluctance while also providing savings in time and other resources. The ALIGN group has been working on this particular challenge by running Intel circuit designs through the tool, and by working closely with industry entities so the tool can be built keeping in mind designers’ needs.

MEGHNA’S ACADEMIC CAREER

Meghna’s undergraduate years had a formative influence on her interest in analog circuits. She undertook projects that involved designing common analog circuits for applications such as the low noise amplifier (LNA) for an RF receiver block that is commonly used in cellular communications. An undergraduate internship designing a software tool proved to be eye opening: Meghna realized that while the specific application she was working on did not excite her, she did have a passion for programming, and programming for a hardware application would be the best of both worlds. Coming to the University of Minnesota was an easy decision: Professor Harjani’s work in analog circuit design was an obvious choice for her. His research and professional experience has been a career inspiration for Meghna, and participation in ALIGN has been in many ways the ideal research opportunity. The work carried out in the project is gaining traction within the EDA community and Meghna presented the research conducted by the group at the DARPA IDEA and POSH program meetings in early 2019, and at the ERI summit in summer 2019.

Meghna views the Cadence scholarship as a significant morale booster. The award affords her the opportunity to invest further in her field of interest in the form of courses, conferences, workshops, and also share her work broadly within the EDA community.

SUSMITA’S RESEARCH

Susmita’s research interest is in the area of domain-specific custom hardware platforms for deep learning (DL) applications, and algorithmic optimizations in VLSI design automation. As part of her research, she has developed an analytical energy simulator for convolutional neural network (CNN) workloads on ASIC-based (application-specific integrated circuit) DL accelerators. Titled CNNergy, the simulator accounts for the complexities of scheduling computations over multidimensional data, while capturing key parameters to automatically map neural computation on the backend hardware. She has also applied CNNergy to drive energy-efficient partitioning of CNN workloads on cloud-connected mobile clients. As part of her effort to expand available tools for ASIC-based DL hardware, Susmita has also developed DeepOpt, a framework which performs layer-specific and hardware-specific scheduling of deep learning workloads to optimize the energy and throughput of the hardware. As a part of the VeriGOOD-ML project, a major undertaking that seeks to build a no-human-in-the-loop Verilog generator for real-time machine-learning hardware, she is currently engaged in developing a performance analyzer that can boost support for DL training on an ASIC platform.

IMPLICATIONS OF SUSMITA’S RESEARCH

Susmita’s research has the potential for far reaching impact. Given that customized neural hardware has wide applicability, and can provide performance gain that is orders of magnitude above conventional machines with CPUs, and GPUs, it is imperative to develop accurate prediction models to perform design evaluations of such hardware. Currently, DL hardware architects have access to only a limited number of tools for performance simulation and design insights. For Susmita, this has been an appealing challenge. It has motivated her to work on the development of specialized simulation platforms and optimization frameworks for domain-specific neural processors. Her work is supported by her interest in backend hardware and algorithmic optimization.

The tools developed by Susmita, CNNergy and DeepOpt, are open-source, allowing the wider community of practitioners to adapt and customize it to specific needs. Capable of providing detailed performance characteristics associated with various components of the network and hardware, the tools can be used to evaluate various design choices for the deployment of deep learning applications. Ultimately, Susmita’s goal is to contribute to the development of industry-standard tools that can guide the design process of neural engines.

SUSMITA’S ACADEMIC CAREER

Susmita’s interest in VLSI circuits and systems started in her sophomore year in college, and by her senior year, the interest was firmly cemented as she gained hands-on experience in VLSI design. Pursuing research opportunities in VLSI system designs and closely allied areas seemed a logical next step. For Susmita, the University of Minnesota was an easy choice given faculty expertise, and strength in disciplinary and interdisciplinary research.

A recipient of the Kevin and AJ KleinOsowski fellowship (2017-2018) and the Peter and Deborah Wexler Graduate Award (University of Illinois at Chicago), Susmita views her Cadence Technology Award as motivational and supportive. It gives her recognition among her peers, and encourages her to continue research in her field of interest.

Prof. Keshab Parhi Named ACM Fellow

The Association for Computing Machinery has named Distinguished McKnight University Professor Keshab Parhi as one of its 2020 ACM Fellows for “contributions to architectures and design tools for signal processing and networking accelerators.”

Professor Parhi is a leader in design techniques and tools that enable hardware accelerators for digital signal processing (DSP) and networking systems, and is well known across the world for his contributions to hardware accelerators, the key building blocks of computing systems. Parhi’s research outcomes have advanced achievable data rates (that would otherwise only have evolved over several technology generations), and made chips more energy and cost efficient. The Gigabit Ethernet chip that has been in use in computers since 1998 is a result of his accelerator designs. Parhi holds 31 US patents, and has authored 650 papers, and his inventions and research have benefited many companies: Broadcom, Marvell, Aquantia, Qualcomm, Samsung, Texas Instruments (TI), and Intel are some of them. In 2003, he was awarded the IEEE Kiyo Tomiyasu Technical Field Award for his groundbreaking contributions to broadband communications systems. In the light of the communication industry’s search for faster and energy efficient technologies as conventional silicon CMOS technologies slow down, Parhi’s work has gained further significance and impact.

Speeding up the internet

Physical layer communications transceiver chips are the backbone of both, wired and wireless internet. The DSP functions and error-control coders in these transceivers contain many layers of feedback loops, and the computation demands cannot be achieved using traditional pipelining and/or parallel processing. Keshab’s research on algorithm-architecture transformations has overcome these bottlenecks and has paved the way for a faster wired and wireless internet.

A pioneer of many forms of look ahead approaches for pipelining and parallel processing in DSP computations, Parhi proposed the pipelining of quantizer loops, using parallel-branch delayed decision. This was particularly critical to companies such as Broadcom, Lucent, and Marvell for the development of the Gigabit Ethernet chip. Parhi’s pioneering and innovative spirit were on display during a stint at Broadcom. When the company struggled to meet the throughput requirements of serializers/deserializers and backplanes for data rates in excess of 10 Gbps, he created arbitrarily-parallel decision-feedback equalizers where the chip complexity grew logarithmically with respect to the level of parallelism, Later, when the linear feedback shift register in Broadcom’s fiber transceiver could not be operated at the 10 Gbps data rate due to the fanout bottleneck, he developed a new parallel linear feedback shift register architecture.

Parhi’s high-speed parallel architecture design of the Tomlinson-Harashima precoder was instrumental in the creation and preservation of the IEEE 802.3an standard for 10-gigabit Ethernet on copper. His fast parallel filters with sub-linear complexity were critical to overcome the excessive costs and energy consumed for data transmission at 10 to 400 Gbps.

His work on parallel decoders is at the vanguard of modern error-control codes that approach the Shannon limit, and his low-latency polar code decoder architectures are in use in 5G smartphones.

Tools for Accelerator Design

Professor Keshab Parhi’s ground-breaking papers on high-level transformations on iterative data-flow graphs (DFGs) include systematic unfolding and folding. Digital filters designed using folding have been deployed in cable modems, set-top boxes and radio-frequency demodulators by companies such as Broadcom, TI, and others. Parhi used folding transformation to develop FFT architectures that achieve full hardware utilization, do not contain feedback loops, and can be pipelined at arbitrary levels. These FFT architectures are incorporated into 5G iPhones.

With the aid of DARPA funding, Parhi developed the Minnesota architecture synthesis (MARS) high level DSP synthesis system. A powerful tool, it has paved the way for synthesis of chips from hardware descriptions to highly pipelined functional units while guaranteeing the fastest possible scheduling. Parhi’s other contributions include crypto-accelerators for RSA and AES for fast secure e-commerce transactions, fast and accurate power estimation (his paper on the topic was named the 1996 ACM/IEEE Design Automation Conference Best Paper, and the technology deployed in Synopsys PowerMill Tool), and obfuscation techniques for hardware security (2017 IEEE Transactions on Very Large Scale Integration Systems Best Paper Award).

Other awards and service

VLSI Digital-Signal-Processing Systems: Design and Implementation (Wiley, 1999), authored by Professor Keshab Parhi is considered an authoritative textbook, and is used by graduate students and practising engineers across the world. The book won him the Frederick Emmons Terman award from the American Society for Engineering Education (ASEE). In his academic tenure so far, he has supervised 48 doctoral theses, 65 master’s theses, 19 visiting pre- and postdoctoral fellows, and numerous undergraduate senior design projects. His students are employed in technology companies, academic institutions, and government research laboratories, with several of them being IEEE Fellows.

Parhi is the recipient of several awards that recognize his brilliant contributions. The most recent awards include the Mac Van Valkenburg Award from IEEE CASS (2017), and Fellow of the American Association for the Advancement of Science (2017). In December 2020, the National Academy of Inventors announced that Professor Keshab Parhi was to be inducted Fellow of the National Academy of Inventors (NAI) in recognition of his “highly prolific spirit of innovation in creating or facilitating outstanding inventions that have made a tangible impact on the quality of life, economic development, and the welfare of society.” The Department of Electrical and Computer Engineering is proud of Professor Parhi’s achievements and congratulates him on his well-earned election as Fellow of the ACM.

Learn more about Distinguished McKnight University Professor Keshab Parhi’s research

Professor Martina Cardone Receives NSF CAREER Award

Professor Martina Cardone has been awarded the CAREER award by the National Science Foundation’s (NSF) Faculty Early Career Development (CAREER) Program. One of the most prestigious awards instituted by the NSF, it recognizes and supports faculty early in their careers who show the potential to “serve as academic role models in research and education and to lead advances in the mission of their department or organization.” The CAREER award minimum for the Division of Computing and Communication Foundations starts at $400,000 and is disbursed over a 5-year period.

Martina’s Project: Secure Communication in mmWave Networks

As wireless communication becomes ubiquitous, commercial entities are increasingly providing information or transacting business, over wireless networks. With the volume of wireless data transfer increasing, the communication industry is turning toward the millimeter-wave (mmWave) spectrum comprising frequencies from 30 gigahertz to 300 gigahertz to support the high data rates.

However, the open and shared nature of the wireless medium, makes it vulnerable to eavesdropping attacks which pose a serious threat to sensitive and confidential information related to mobile banking, credit card transactions, and health data. Today, the assumption that eavesdroppers have limited computational capabilities is one that is seriously placed in doubt by recent advances in (quantum) computing. Yet, in large and dense mmWave networks, it is reasonable to assume that an eavesdropper can intercept transmissions only over a subset of the communication links over which she has to be physically present.

Titled, “Foundations of Secure Communication in mmWave Networks,” Martina’s CAREER award winning project seeks to address the challenges posed by such threats by exploring and establishing protocols that can ensure secure communication over millimeter-wave (mmWave) networks, in the presence of an eavesdropper with unlimited computational capabilities but limited network presence.

The highlight of the project is the establishment of novel theoretical foundations that identify and model unique features of secure communication in the mmWave spectrum, and the study of their effect on the operations in the network layer. Martina’s research is multidisciplinary, and it leverages concepts and tools from other fields including information theory, optimization and linear programming, algorithms, and graph theory. The key specifics of her project include: introduction of a theoretical framework that captures the essentials of mmWave communication and eavesdropper capabilities; characterization of the maximum secure information flow and trade-offs over mmWave networks; and finally, the development of scalable and secure communication architectures.

Practical and Educational Outcomes

Upon successful completion of the project, Martina hopes to provide guidelines for the design of secure transmission mechanisms over mmWave networks. Given that the mmWave communication is expected to play a key role in supporting a variety of applications, and the pressing need for protocols that will maintain the confidentiality of data, the current project is compelling and can make significant and timely contributions to industrial and societal needs.

Martina has plans to share and integrate her research outcomes with students and the curriculum in several ways. As chair of the Student and Outreach Subcommittee of the IEEE Information Theory Society, she will use the opportunity to facilitate knowledge sharing of her project research. She also hopes to tap into the outreach opportunities available within the University of Minnesota and the ECE department. Other critical and relevant educational undertakings that Martina plans to pursue are the development of a graduate-level course on mechanisms to secure communication over wireless networks, mentoring of undergraduate students through avenues such as senior design projects, conference participation, and creation of short videos to share the information with a broader audience of students beyond the University of Minnesota.

Professor Martina Cardone earned her doctoral degree in 2015 from Télécom ParisTech, France with work done at Eurecom. From 2015 to 2018, she held postdoctoral positions at UCLA’s Henry Samueli School, and the University of Minnesota in ECE. In early 2018, she joined the Department of Electrical and Computer Engineering as an assistant professor. Her research interests are in estimation theory, network information theory, network coding, wireless networks with a special focus on their capacity, security, and privacy aspects. Besides the CAREER award, Martina also leads two other NSF-funded projects.

Learn more about Professor Martina Cardone’s work

Alumnus Tianyi Chen Receives IEEE SPS Best Dissertation Award

Alumnus Tianyi Chen is the inaugural recipient of IEEE Signal Processing Society’s (SPS) Best Dissertation Award. Chen, now a faculty member at Rensselaer Polytechnic Institute (RPI), earned his doctoral degree in 2019 under the supervision of Professor Georgios B. Giannakis. His dissertation is titled “Efficient Methods for Distributed Machine Learning and Resource Management in the Internet-of-Things.”

Chen’s dissertation addresses the challenges emerging from training machine learning models over the wireless network by focusing on a unified algorithmic framework for distributed machine learning and resource management. The framework encompasses a set of new computational methods that make quantifiably better use of limited resources (such as communication, memory, and energy), and require minimal modeling assumptions compared to existing methods. The new distributed machine learning algorithms demonstrate significant improvement in resource efficiency, and the new model-free resource management schemes achieve performance competitive to existing model-based methods.

An assistant professor with the Electrical, Computer, and Systems Engineering Department at RPI, Chen’s current research focuses on signal processing, machine learning, and optimization, and their applications to wireless networks. As a student at the University of Minnesota, he was also a recipient of the Doctoral Dissertation Fellowship.

The IEEE SPS Best Dissertation Award “recognizes PhD relevant work in signal processing while stimulating further research in the field.” The criteria for evaluation are scientific impact of the research (evidenced by factors such as citations, journal papers published from the dissertation, awards, patents, adoption into practice, and others), and overall quality of the dissertation as seen in factors such as the quality and rigor of scientific method, and significance and timeliness of the research.

Prof. Keshab Parhi to be Inducted Fellow of National Academy of Inventors

Distinguished McKnight University Professor Keshab K. Parhi has been elected as Fellow of the National Academy of Inventors (NAI). The NAI Fellows Selection Committee recognizes that he has “demonstrated a highly prolific spirit of innovation in creating or facilitating outstanding inventions that have made a tangible impact on the quality of life, economic development, and the welfare of society.”

Parhi’s election is richly deserved. It reflects his contributions and commitment to his field of expertise, VLSI architectures and integrated circuit design. He holds 31 US Patents (besides 3 that are pending) in high-speed and low-power transceiver architectures for the internet and cryptosystems, and hardware security. His inventions have fundamentally changed and significantly improved data transmission speeds of communication transceivers. His inventions on pipelining and parallel processing of decision feedback decoders are used by several key technology companies. Parhi’s inventions on low-latency Viterbi decoders, and error control coder architectures are in use in wireless systems. His work on pipelined architectures for the advanced encryption standard (AES) enables millions of secure transactions per second, and his research on polar code decoders and fast Fourier transform are used in smart phones.

Parhi’s work has been of direct significance to companies and users in the communications field. With his research and inventions being licensed and/or assigned to companies such as Broadcom, Infineon, and member companies of the Semiconductor Research Corporation; the impact of his work is felt by anyone using the internet in the speed and secure transactions it offers.

Reflecting on the importance of inventions that stem from academia, and being elected as Fellow, Parhi says:
About 25 years ago, Dr. Cliff Lau, my then program director at the Office of Naval Research, mentioned to me that, in addition to writing papers, I should think about patenting some of my work. That was excellent advice. We patented some of my work out of the university and several have been licensed to Infineon and the Semiconductor Research Corporation. I took a leave from the University of Minnesota to work at Broadcom from 2000 to 2002 and my research at Broadcom led to nine patents and these inventions were incorporated into numerous networking products for copper and optical cables at Broadcom. My former students and I also patented numerous ideas on behalf of Leanics, a small company that I had founded and was active during 2005-2012. Several of my former Ph.D. students who were co-inventors of the patents are now cofounders and CTOs of their startups. I am pleased that the National Academy of Inventors has elected me as a Fellow in recognition of my efforts in patenting and training Ph.D. students in patenting.

TEACHING AND SERVICE

As a faculty member in the Department of Electrical and Computer Engineering, Parhi has mentored and guided his students on innovation, invention, and the patenting process. It is a testimony of his dedication to his field as a teacher, mentor and researcher that many of his former students have gone on to found or co-found startup companies. In his academic tenure so far, he has supervised 48 doctoral theses, 65 master’s theses, 19 visiting pre- and postdoctoral fellows, and numerous undergraduate senior design projects. His students are employed in technology companies, academic institutions, and government research laboratories.

Parhi has tirelessly volunteered his time and expertise for numerous IEEE and ACM committees. He served as a member of the Board of Governors of the IEEE Circuits and Systems Society (CASS) (2005-2007), and chaired technical and awards/fellow committees of IEEE, and IEEE CASS. He was editor-in-chief of IEEE Transactions on Circuits and Systems (2004-2005) and associate editor 14 times. He has also served as general chair, technical program chair, and program committee member for several conferences. He served as Director of Graduate Studies of the Electrical Engineering Program at the University from 2008 to 2011.

CAREER ARC

Prof. Keshab Parhi joined the University of Minnesota in 1988 having completed his PhD in September 1988 at the University of California, Berkeley. He is Edgar F. Johnson Professor of Electronic Communication and Distinguished McKnight University Professor. He has worked with key technology companies such as Broadcom, Medtronic, and others while on leave from the University. In 2005, he founded Leanics Corporation, and was CEO/CTO from 2005 to 2012. The company was awarded four SBIR Phase-I grants and one SBIR Phase-II contract. It raised over $1.3M and employed several of his PhD students.

Prof. Parhi has been the recipient of numerous awards in recognition of his research and service contributions. His most recent awards include the Mac Van Valkenburg Award from IEEE CASS (2017); Fellow of the American Association for the Advancement of Science (2017); Distinguished Alumnus Award from alma mater IIT, Kharagpur, India (2013); Graduate/Professional Teaching Award, University of Minnesota (2013); Charles A. Desoer Technical Achievement Award from IEEE CASS (2012); IEEE Kiyo Tomiyasu Technical Field Award (2003); IEEE W.R.G. Baker Best Paper Award (2001); and the IEEE CASS Golden Jubilee Medal (2000). These, of course, are only a few of the awards Parhi has received in a career that is studded with numerous honors that speak to his brilliance and commitment to research, invention, and teaching. The Department of Electrical and Computer Engineering is proud of Professor Parhi’s achievements and congratulate him on his induction as Fellow of the NAI.

The Fellows Induction Ceremony will take place on June 7-9, 2021 in Tampa, Florida. With this recognition, Parhi will join the ranks of five University of Minnesota faculty who are Fellows of NAI, including Prof. Georgios Giannakis from ECE, who was inducted in 2019.

Founded in 2010, the NAI is a member organization comprising domestic and foreign universities, and government and non-profit research institutes. It has over 4,000 individual inventor members and Fellows spanning more than 250 institutions worldwide. Its goal is to “recognize and encourage inventors with patents issued from the U.S. Patent and Trademark Office, enhance the visibility of academic technology and innovation, encourage the disclosure of intellectual property, educate and mentor innovative students, and translate the inventions of its members to benefit society.”

ECE researchers report ultrastrong coupling of light and phonons within nanoscale coaxial cable

Opens up possibilities for developing new quantum-based devices

A multi-institutional team of scientists led by ECE’s Professor Sang-Hyun Oh have reported vibrational ultrastrong coupling of light and matter within nanocavities at mid-infrared frequencies (MIR). The finding is particularly significant because it throws open a new frontier in cavity quantum electrodynamics (QED) that could enable quantum-based devices and even modify chemical reactions. The results are published in their paper titled, “Ultrastrong plasmon–phonon coupling via epsilon-near-zero nanocavities,” in Nature Photonics, a premier journal in the field of photonics. The report is the result of scientific collaboration among researchers at the University of Minnesota and other domestic and foreign institutions (names of collaborating institutions and authors included at the end).

Commenting on the significance of the study, corresponding author and University of Minnesota professor Sang-Hyun Oh says, “Researchers have studied coupling, but with this process we are pushing the frontiers of ultrastrong coupling. We are discovering new quantum states where matter and light can have very different properties and unusual things start to happen. This ultrastrong coupling of light and atomic vibrations opens up all kinds of possibilities for developing new quantum-based devices or modifying chemical reactions.”

A PRIMER ON LIGHT MATTER INTERACTIONS

The interaction between light and matter is central to life on earth. It allows for such fundamental phenomena as plants converting sunlight into energy, and allows us to see objects around us. At a more complex and less obvious level, infrared light, with wavelengths longer than that of visible light, interacts with the vibrations of atoms in materials. For example, when an object is heated, the atoms that make up the object start vibrating faster, giving off more infrared radiation enabling thermal-imaging, a phenomenon harnessed for night-vision cameras. Conversely, the wavelengths of infrared radiation that are absorbed by materials depend on what kinds of atoms make up the materials and how they are arranged. Chemists can use such infrared absorption spectrum as a “fingerprint” to identify different chemicals.

These and other applications can be improved by manipulating the strength with which infrared light interacts with atomic vibrations in materials. This can be accomplished by trapping the light into a small volume that contains the materials. Trapping light can be as simple as making it reflect back and forth between a pair of mirrors, but much stronger interactions can be realized if nanometer-scale metallic structures, or “nanocavities,” are used to confine the light on ultra-small length scales.

Until recently, light-matter interaction in the field of cavity QED had been confined to weak coupling and strong coupling. The strong coupling phenomenon can enable quantum information processing, and energy states with properties different from the original matter which can in turn change the chemical characteristics of the participant matter.

When nanocavities are used to trap light, the interactions can be strong enough that the quantum-mechanical nature of the light and the vibrations comes into play. Ultrastrong coupling (USC), a recent entrant to light-matter interactions, is a regime in which far more exotic phenomena can occur because of the strength of the light-matter coupling. In this mode, the absorbed energy is transferred back and forth between the light (photons) in the nanocavities and the atomic vibrations (phonons) in the material at a rate fast enough that the photon and phonon can no longer be distinguished. These strongly coupled modes make up new quantum-mechanical objects known as polaritons. The stronger the interaction, the more exotic the quantum-mechanical effects that can occur. If the interaction becomes strong enough, it may be possible to create photons out of the vacuum, or make chemical reactions proceed in ways that are otherwise impossible. This state has the potential to enable novel ultrafast optoelectronic devices, modify chemical reactions, and one can even extract light from the modified ground state.

Commenting on the unusual idea of creating something out of a vacuum, co-corresponding author of the paper, Professor Luis Martin-Moreno at the Instituto de Nanociencia y Materiales de Aragón (INMA) in Spain says, “It is fascinating that in this coupling regime, vacuum is not empty. Instead, it contains photons with wavelengths determined by the molecular vibrations. Moreover, these photons are extremely confined and are shared by a minute number of molecules.”

Professor Oh adds, “Normally we think of vacuum as basically nothing, but it turns out that this vacuum fluctuation always exists. This is an important step to actually harness quantum vacuum fluctuation to do something useful.”

USC has previously been demonstrated by means such as photochromic molecules, superconducting circuit QED systems, two-dimensional electron gases, and others. Strong coupling at mid-infrared frequencies have also been demonstrated in various systems showing their use for applications such as thermal emission and signature control, and modified heat transfer. However, the challenge has been to attain ultrastrong coupling at MIR frequencies, particularly in solid-state systems. Previous demonstrations have involved extended microcavity structures which limit the possibilities for novel nonlinear effects.

SIGNIFICANCE OF THE STUDY

Commenting on the significance of the study, corresponding author and University of Minnesota professor Sang-Hyun Oh says, “Researchers have studied coupling, but with this process we are pushing the frontiers of ultrastrong coupling. We are discovering new quantum states where matter and light can have very different properties and unusual things start to happen. This ultrastrong coupling of light and atomic vibrations opens up all kinds of possibilities for developing new quantum-based devices or modifying chemical reactions.”

Emphasizing the profound implications that USC can have for chemistry, professor Joshua Caldwell of Vanderbilt University says: “A specific chemical may typically react with another through the thermodynamically favorable pathway. Thermodynamics drives that reaction. However, by strongly coupling a photonic cavity to the vibration of a competing bond in the initial molecule, the process could induce that bond to break first, giving it the preferential position to react and thus changing the resultant product chemical.”

In other words, the same two reactants would produce different products.

An electron micrograph of annular holes in a gold film with a 10 nm gap and 200 nm diameter. The holes filled with silicon dioxide enable ultrastrong coupling between light and atomic vibrations. Image credit: Oh Group, University of Minnesota

The current study has broken through barriers that have constrained previous demonstrations of light-matter interaction. The team demonstrated vibrational USC in nanocavities at the technologically important MIR frequencies, which is a significant breakthrough for multiple reasons. The size of the cavity is a critical first: at 2 nm, it is a nanoscale version of a coaxial cable (approximately 25,000 times thinner than a strand of human hair), which is filled with silicon dioxide. This drastically reduces the size of the system.

“The tiny coaxial holes that enabled our experiments were manufactured using a new technique called atomic layer lithography. This method is compatible with standard processes used in the microelectronics industry and makes it possible to produce millions of nanocavities simultaneously, with all of them exhibiting this ultrastrong photon-vibration coupling. We are excited about finding new ways to contribute to the field of cavity QED using our technique,” says lead author of the paper, Daehan Yoo.

To sum it up, the study demonstrates significant improvement on 3 fronts: performance, efficiency, and scalability. These factors are critical to open and/or extend new pathways for research and development in several areas: quantum nonlinear optics, multiphoton effects, and single-photon excitation are some of them. Although the study is currently at the level of fundamental research, it holds the potential for the development of novel applications in the future such as new light sources, optoelectronic devices, and setting up chemical reactions in ways that were previously not possible.

Prof. Sang-Hyun Oh is a Distinguished McKnight University Professor, and holds the Sanford P. Bordeau Chair in Electrical and Computer Engineering. Learn more about research in his Laboratory of Nanostructures and Biosensing.

In addition to Oh and Martin-Moreno, the research team included Daehan Yoo, In-Ho Lee, and Daniel A. Mohr, University of Minnesota; Fernando de León-Pérez, Centro Universitario de la Defensa de Zaragoza and Instituto de Nanociencia y Materiales de Aragón (INMA) in Spain; Matthew Pelton, University of Maryland at Baltimore County; Markus B. Raschke, University of Colorado Boulder; and Joshua D. Caldwell, Vanderbilt University.

Daehan Yoo earned his PhD from the University of Minnesota in 2016 and is a postdoctoral associate in Prof. Sang-Hyun Oh’s laboratory.

The research was funded by the U.S. National Science Foundation and the Samsung Global Research Outreach Program. Additional support was provided by the Spanish Ministry of Economy and Competitivity, Aragón Government Project, U.S. Office of Naval Research, and the Sanford P. Bordeau Chair in Electrical Engineering at the University of Minnesota.

*The cover illustration shows annular holes in a gold film with a 10 nm gap and 200 nm diameter. The holes filled with silicon dioxide enable ultrastrong coupling between light and atomic vibrations. Image credit: Oh Group, University of Minnesota

Prof. David Lilja Receives BenchCouncil Achievement Award

Prof. David Lilja has been recognized with the BenchCouncil Achievement Award by the International Open Benchmark Council. The award recognizes a senior researcher for their long-term contributions to benchmarking, measuring, and optimizing computer performance. The award citation for Prof. Lilja reads, for contributions to “summarizing practical methods of measurement, simulation and analytical modeling,” “proposing MinneSPEC for simulation-based computer architecture research,” and “exploiting hardware-software interactions and architecture-circuit interactions to improve system performance.”

Prof. Lilja’s research interests focus on computer architecture, high-performance parallel computing, computer systems performance analysis, approximate computing, and storage systems. His team of researchers is particularly focused on the interaction of software and compilers with computer architecture, and the interaction of computer architecture and circuits.

Besides being a faculty member in ECE, Lilja also serves on the graduate faculties of Computer Science, Scientific Computation, and Data Science. He has chaired and served on the program committees of numerous conferences, and was a distinguished visitor of the IEEE Computer Society. He was elected a Fellow of the Institute of Electrical and Electronics Engineers (IEEE) and a Fellow of the American Association for the Advancement of Science (AAAS) for contributions to the statistical analysis of computer performance. He also is a member of the ACM, and is a registered Professional Engineer.

Lilja was a recipient of a Fulbright Senior Scholar Award to visit the University of Western Australia, was a visiting Professor at the University of Canterbury in Christchurch, New Zealand, and was awarded a McKnight Land-Grant Professorship by the Board of Regents of the University of Minnesota.

Prof. Lilja accepted the BenchCouncil Achievement Award on Nov. 15, 2020, at the virtual meeting of the 2020 BenchCouncil International Symposium on Benchmarking, Measuring, and Optimizing (Bench’20).

International Open Benchmark Council (BenchCouncil) is a non-profit research institute which aims to promote the standardization, benchmarking, evaluation, incubation, and promotion of open-source chip, AI, and Big Data techniques.

Prof. Rhonda Franklin Shares Her Experiences Leading to Her ARCS Scientist of the Year Award

Prof. Rhonda Franklin has been named Scientist of the Year for 2020 by the ARCS Foundation Minnesota chapter. The award recognizes her work “mentoring and encouraging students to follow careers in science.” The honor is not surprising considering Prof. Franklin’s history of deep and sustained engagement with students and young professionals, helping them meet their goals, and grooming them to be future leaders in STEM careers. 

CHAMPIONING STUDENT SUCCESS:

Participation in the University’s Undergraduate Research Opportunity Program (UROP), and the NSF-sponsored Research Experience for Undergraduates (REU) program are just a couple of examples of Franklin’s keen dedication to helping students succeed. She was instrumental in the founding of the IEEE Women in Engineering (WIE) student branch at the University, and served as its first faculty advisor. As an engineer and scientist, she has been an active member of IEEE, planning and participating in programs that introduce students to microwave and wireless technologies, which are her specific areas of research interest. She has a long and distinguished record of active engagement and achievements not only as a scientist, but also as a mentor helping her students and other charges through professional development and career planning.

Listen to Prof. Franklin describe her experiences leading to the ARCS award.
(Our thanks to Barbara Goergen and Judith Benham of the Minnesota chapter of the ARCS Foundation for making the video available.)

In 2014, she co-founded IMS Project Connect which is aimed at familiarizing undergraduate and first year minority and women students with the microwave community and industry by facilitating collaboration with the MTT Society through the symposium. She has worked with co-founders, professors Thomas Weller and Rashaunda Henderson, to plan the program which includes developing communication and networking skills, understanding workplace expectations, career opportunities in microwave engineering in industry, academia, and government, and facilitating meetings with industry leaders and scientists.

Franklin’s dedication to the overall success of her students is seen in the recent presentations of Yali Zhang and Aditya Dave at the College of Science and Engineering 3MT Competition. The crisp 3 minute descriptions of their doctoral research that Zhang and Dave present are examples of Franklin’s work helping students develop their hard (research) as well as soft (communicsations) skills. Both students were selected to compete in the final round of the International Microwave Symposium 3MT competitions, Zhang in 2019, and Dave in 2020.  

Franklin was the recipient of the 2016-17 John Tate Award for Excellence in Undergraduate Advising, and in 2019 she received the N. Walter Cox Award for her exemplary service to the IEEE Microwave Theory and Techniques Society. Recently, Prof. Rhonda Franklin also received the IEM Abbott Professorships in Innovative Education awarded by the Institute for Engineering in Medicine. She is an inaugural recipient and shares the award with Prof. Chris Pennell of the Department of Laboratory Medicine and Pathology. These Abbott Professorships are awarded to the faculty co-directors of the IEM Inspire Program which aims to motivate students to pursue STEM careers in medicine and healthcare. 

The Department of Electrical and Computer Engineering is proud of Prof. Franklin’s achievements and laud her contributions supporting future STEM leaders. 

Learn more about Prof. Rhonda Franklin’s research interests here.

Sandeep Avvaru’s Thesis Advances to Midwestern Association of Graduate Schools’ 2021 Distinguished Master’s Thesis Competition.

Doctoral candidate Sandeep Avvaru’s master’s thesis has been selected by the University’s Graduate School to advance to the Midwestern Association of Graduate Schools’ (MAGS) Annual Distinguished Master’s Thesis competition. He will also be receiving an honorarium from the University of Minnesota.

Sandeep’s thesis addresses privacy and security concerns related to electronic devices by shedding new insights on the fundamental properties of arbiter PUFs (physical unclonable functions). PUFs are lightweight hardware security primitives used to authenticate devices and generate cryptographic keys without using non-volatile memories. This is accomplished by harvesting the inherent randomness in manufacturing processes to generate random yet unique outputs. Although PUFs are becoming increasingly popular, modeling attacks restrict their usage. Sandeep’s work brings the PUF community closer to realizing secure, reliable, and unique lightweight PUFs.

Currently, Sandeep is working on the analysis and introduction of changes in neural activity to enhance cognitive control through deep brain stimulation (DBS). He is being advised by Prof. Keshab Parhi of ECE and Prof. Alik Widge from the Department of Psychiatry. Having always been fascinated by the inner workings of the brain and the nervous system, research in the area seems a natural progression Sandeep. He hopes that better knowledge of the cognitive control process will bring about improved and more effective treatment options. 

Sandeep’s doctoral research topic is supported by his broader interests in signal processing, computational neuroscience, neuromodulation and machine learning, all of which have helped him unravel and understand how the brain functions. He is a recipient of the the MnDrive Graduate Fellowship in Neuromodulation funded by the Brain Conditions area of the Minnesota Discovery, Research and InnoVation Economy (MnDRIVE) initiative.

CSE 3MT Competition winners: Yali Zhang Places 1st, Aditya Dave is People’s Choice

Congratulations to Yali Zhang for placing first, and Aditya Dave for winning the people’s choice award at the CSE-level 3MT competition. The competition is open to doctoral students and the challenge is to present their research in 3 minutes in a compelling manner to a non-scientific audience. ECE students Yali and Aditya (both completing their doctoral research under the guidance of Prof. Rhonda Franklin) stood up to the challenge effectively. Originating at the University of Queensland, the 3MT competition is now adopted by 85 countries with over 200 participating institutions. Learn more about the competition here.

Yali Zhang’s Research Interests

Born in Changsha, China, Yali earned her bachelor’s degree in electrical engineering from Sichuan University. Her interest in the field of radio frequency (RF) technology brought her to the University of Minnesota, where she has been a part of Prof. Franklin’s MPACT research group. Yali has been studying the application of nanostructures in RF technology in the millimeter and sub-millimeter wave range. The relative newness of the topic, and its potential ability to improve lives, from our digital experience to our health has been a driving impetus for her.

Image of Doctoral Student Yali Zhang
Doctoral Student Yali Zhang

Currently, Yali’s work delves into RF properties, and applications of magnetic and non-magnetic nanostructures, especially for future communication and nanomedicine technologies. Future sub-millimeter wave communication systems are the key to internet of things devices, autonomous vehicles, and low-power CubeSats. Magnetic nanostructure-based bio-label is essential to meet nanomedicine technology’s goals of providing precise detection of pathological changes, and targeted therapy. Both areas demand effective designs and measurement techniques for nanoscale devices in micrometer-scale integration.

As part of her doctoral research, Yali is working on characterizing magnetic and non-magnetic nanowires, and applying them in device components. Based on magnetic nanowires characterization technology, a nano-labeling system can be built, and small-sized non-reciprocal devices can be designed accurately. Her study of non-magnetic copper oxide nanowires holds the potential to develop low-loss, fast-speed 3D integrated circuits.

Watch Prof. Franklin’s student, Yali Zhang describe her doctoral research in 3 minutes

Yali’s goal is to develop accurate and sensitive methods to characterize nanowires to be used for cell labeling and circuitry components for 5G and 6G communication applications. After graduation, she plans on applying knowledge gained through her research towards solving real life problems, drawing on diverse disciplines such as biology and material science for RF circuits and designs.

Aditya Dave’s Research Interests

Aditya is from Mumbai, India, and earned his bachelor’s degree from BITS Pilani, India in 2017. Prof. Rhonda Franklin’s research coincided with his own interests, and he started his doctoral work in ECE the same year.

Watch Prof. Franklin’s student, Aditya Dave describe his doctoral research in 3 minutes
Image of Aditya Dave
Doctoral student Aditya Dave

Aditya’s research lies in electromagnetics and its applications, and he is currently working on antenna technology. A significant element of his doctoral endeavor is the development of efficient designs for planar antennas with a dielectric lens. These types of systems have the potential to extract higher performance from relatively small and compact antennas through increased efficiency. As part of his research, Aditya has designed efficient lenses that split radiation originating from an antenna into multiple near-field identical beams, which make these systems viable for a range of near-field and far-field applications.

Aditya is currently exploring these applications. One of the near field applications is developing free-space miniature power dividers that can also act as vertical interconnects in integrated circuits. Far-field applications include the possibility of developing passive beam steering virtual antenna arrays and remote sensing applications such as measurement of water content in the soil, for plants. The latter was the focus of his presentation for the 3MT Competition hosted by the College of Science and Engineering. His goal for his thesis is to build and test prototypes for one or more of his applications.

After earning his doctorate, Aditya hopes to gain experience either through an industrial or post-doctoral appointment that will round out his skills in the area. Eventually he would like to pursue a research centered career that is rooted in applications for the space sector.