April 18, 2023
Dr. Kaushik Seshdreesan is an assistant professor in the Department of Informatics and Networked Systems. He said the goal of his research agenda is “to develop quantum information technologies and connect them over a robust quantum internet for applications with deep societal impact.” Describing the potential benefits of his research, Seshdreesan observed that, “There is this exciting new paradigm for information processing where information is encoded over quantum states of matter and light, and the performance capabilities are governed by the laws of quantum mechanics. It is still largely uncharted territory with exciting prospects for new applications in computing, communications, and sensing with enhanced capabilities."
"The questions are, how well can we really process information in this new paradigm? What are the ultimate limits? How do you achieve those limits? What are the kinds of problems that you can solve faster on a quantum computer, as compared with a classical computer (i.e., our existing computers)? How well can you detect feeble signals with the help of novel quantum sensors? How do you connect quantum computers, quantum sensors, and other gadgets in order to form networks?”
Seshadreesan has a background in both electrical engineering and physics, saying that when he completed his bachelor’s degree, he “was looking at emerging areas that actually directly feed off of the most fundamental, cutting-edge theories of physics, which happens to be quantum mechanics. Quantum computing was just emerging as an important future direction.” Quantum computing involves information units called quantum bits, or qubits. An ordinary bit can have either a zero or a one as its value, whereas a qubit can express both values simultaneously. “These cubits are used not only for quantum computing but also become very useful and good at encoding information for communication,” he said. Seshadreesan said his attention is currently focused on working with “novel architectures of qubits encoded in light that have good error correction properties, such as the so-called Gottesman-Kitaev-Preskill qubits, which are robust against photon loss errors, and implementing universal quantum logic with such qubits.”
Seshadreesan is also using qubits and quantum logic to “build quantum receivers for classical communications with laser light at enhanced data rates in contexts where the receiver power is low. In other words, you only receive feeble laser pulses. As it turns out, using suitable qubits as ancillas and processing the received feeble laser pulses coherently, one can attain enhanced data communication rates.” Identifying the potential applications of such research, Seshadreesan said that such technology “is very significant and relevant to NASA’s future space programs.” Another one of Seshadreesan’s forthcoming projects is funded by Cisco and concerns a quantum switch, which is a vital component for realizing a future quantum internet. Seshadreesan explained that his work will involve “designing scheduling policy for a quantum switch that is going to connect so-called continuous variable quantum links.” A third project investigates quantum sensing, deploying a “so-called nitrogen vacancy qubit” that is extremely sensitive to magnetic field fluctuations. He said this research is being pursued collaboratively with researchers in the Department of Physics and is geared “towards building magnetometers for medical applications.”
Seshadreesan’s graduate courses offer opportunities for students to learn more about how to conduct quantum computing research. In the fall of 2022, he taught a seminar course titled “Quantum Information Technologies.” This semester, he is teaching a course titled “Quantum Information and Error Correction.” He said, “My research directly builds off of the current course I’m teaching, which is very action-packed and tries to cover two distinct theories, quantum information theory and quantum error correction, in a single semester.” While fast-paced, Seshadreesan said, “I’ve tried to distill the essential concepts from both the theories, such that my students can directly use this knowledge and the kind of research that we do.”
--Daniel Beresheim