After graduating from Georgia Tech with her Ph.D. in 2008, Zajic spent a year as a postdoctoral fellow at the Naval Research Laboratory and two years as a visiting assistant professor in Tech's School of Computer Science. In 2012, she joined ECE as an assistant professor, and in 2017, she was promoted to associate professor. 

Zajic leads the Electromagnetic Measurements in Communications and Computing Laboratory, where she advises 10 Ph.D. students and two postdoctoral fellows who work in the areas of propagation, enabling communication, and improving data security in challenging environments, such as vehicle-to-vehicle wireless radio communications, underwater acoustic communications, and communications inside a processor chip. To date, Zajic has graduated nine Ph.D. students and five M.S. students. She advises undergraduate students on individual projects and through the Opportunity Research Scholars Program. Zajic and her research group have received six best paper, poster, or demonstration awards since she joined ECE as a faculty member.

Zajic’s specific research interests focus on understanding mechanisms that generate electromagnetic (EM) side-channel emanations in modern computers and on locating sources of information-carrying EM emanations in complex environments. She has received over $18 million in research funding as a PI or co-PI, mostly from NSF, DARPA, the Office of Naval Research, and the Air Force Office of Scientific Research. Zajic has published over 140 refereed journal and conference publications. She has three awarded patents and five patent applications pending. Her work has been publicized locally and internationally through The Atlanta Journal-Constitution, NSF Science 360, Voice of America, Wired, and many other outlets. Zajic has served as an editor of the IEEE Transactions on Wireless Communications and Wiley Transactions on Emerging Telecommunications Technologies. She also served as the chair of the Atlanta chapter of the IEEE Microwave Theory and Techniques Society/Antennas and Propagation Society from 2015-2017, and during that time, the group received the IEEE Outstanding Chapter Award in 2016. She received the IEEE Atlanta Section Outstanding Engineer Award in 2019. 

Equally devoted to teaching excellence and service, Zajic has developed or redesigned both undergraduate and graduate courses and has taught a flipped classroom version of ECE 3025–Electromagnetics. For her efforts, she has received several teaching awards, including the Richard M. Bass/Eta Kappa Nu Outstanding Junior Teacher Award in 2016 and the LexisNexis Dean’s Excellence Award in 2016-2017. Zajic has also participated in the Center for Teaching and Learning’s Class of 1969 Teaching Scholars Program. She is an active member of the ECE and Georgia Tech community, currently serving as the director of the M.S. Cybersecurity degree program; a member of the ECE Statutory Advisory Committee; a member of the College of Engineering Reappointment, Promotion, and Tenure committee; and a member of a working group on the professional development of graduate students, an initiative coordinated from the Provost’s Office.