I defended my PhD at The Chinese University of Hong Kong in June 2025. Seven months later, I am a postdoctoral researcher at Jilin University. In between, I graduated, moved countries, started a new position, and began adjusting to a role that is familiar in some ways and completely different in others.
This post is an account of what that transition has felt like, written while the experience is still fresh. It is not advice. I have not been a postdoc long enough to give advice. It is more like a field report from someone still figuring things out.
The Last Year of the PhD
My final year was intense in ways I had not anticipated. I knew the thesis would take time, but I underestimated how much mental energy the finishing phase would consume.
Writing up results I had been working on for years felt surprisingly difficult. Not because I did not understand the work, but because explaining it clearly, in a coherent narrative that a committee member outside my specific subfield could follow, required a different kind of effort. I had to step back from the technical details I had been immersed in and ask: what is the story here? Why should anyone care?
The defense itself went well. The committee was fair, the questions were serious but not hostile, and I walked out with a deep sense of relief. What surprised me was the emptiness that followed. For four years, every decision had been oriented toward the thesis. Suddenly the thing I had been working toward was done, and the next phase had not yet begun.
I spent the time between defense and the start of my postdoc catching up on sleep, reading papers I had been putting off, and trying to remember what I did for fun before graduate school.
Starting Over
Moving to Jilin University in January 2026 meant a new country, a new department, a new set of colleagues, and a new mathematical environment. I knew this intellectually, but the reality of it still caught me off guard.
As a PhD student, I had spent four years building a network: I knew the seminars, the lunch crowd, the people working on adjacent problems, the librarians, the IT support staff who could fix the cluster when it went down. All of that disappeared overnight. At my new institution, I started from scratch. Learning where the printers are, how to access the computing resources, which seminars are worth attending, who is working on what.
The research environment is different too. My PhD was at a department with a strong inverse problems group. At Jilin, my immediate colleagues work on a broader range of problems, and I am, for the first time, the person in the department most closely associated with EIT and learned regularization. This is simultaneously exciting (more freedom, less crowding of the niche) and isolating (fewer people to discuss technical minutiae with over coffee).
What Changed
Independence. This is the most significant shift. During my PhD, I met with my advisor regularly. We discussed directions, he warned me when I was heading down an unproductive path, he helped me see problems from angles I had not considered. That support structure is largely gone.
My postdoctoral mentor is generous with his time, but the relationship is fundamentally different. I am expected to set my own research agenda, choose my own problems, manage my own time. Nobody checks whether I am making progress. Nobody tells me which papers to read. The freedom is real, and so is the vertigo that comes with it.
Breadth of responsibility. As a PhD student, my job was to solve my research problem and pass my courses. As a postdoc, I am also expected to mentor junior students, review papers, contribute to grant proposals, attend committee meetings, and maintain professional visibility. None of these tasks were in my training, and each one takes time away from the research that is ostensibly my primary job.
Time pressure. A PhD takes as long as it takes. A postdoc is a fixed-term position. The clock is ticking from day one. I need to publish, build a track record, develop collaborations, and position myself for the next step, all within a short window. This awareness changes how I approach problems. I am more strategic about which projects to pursue, more conscious of whether a direction is likely to produce results in the available time.
Identity. During my PhD, I was “Jun Zou’s student.” This provided a framework: I worked on problems connected to my advisor’s program, I was introduced at conferences through that affiliation, and the reputation of the group lent credibility to my work. Now I am building my own identity. When I introduce myself, the question is: what do I work on, and why is it interesting? The answer has to come from me, not from my advisor’s name.
What Did Not Change
The daily work. I still spend most of my time reading papers, working through proofs on paper, writing code, debugging numerical experiments, and drafting manuscripts. The core activities of doing mathematics have not changed at all. The tools are the same, the challenges feel familiar, and the satisfaction of understanding something new is identical.
The imposter feelings. I thought these would go away after finishing the PhD. They did not. If anything, they intensified briefly after the move. Sitting in a seminar at a new institution, surrounded by people whose work I admire, the old thought returns: do I belong here? The answer, I have learned, is that almost everyone feels this way. It does not mean the feeling is accurate.
The importance of routine. I need structure to be productive. Without the scaffolding of coursework and advisor meetings, I had to build my own. I block mornings for deep mathematical work, handle emails and administrative tasks in the afternoon, and try to protect at least two hours per day for uninterrupted thinking. This took a few weeks to calibrate, and it still breaks down regularly.
Things I Wish I Had Known
The administrative load is real. I was not prepared for how much time goes to non-research tasks. Setting up accounts, obtaining access to computing resources, filling out forms, attending orientations. In my first month, I estimate that less than half my time went to actual research.
Loneliness is normal. Moving to a new city where you know nobody, starting a job where you are the new person, working on problems that few people around you share: it adds up. I have had to be deliberate about building connections, attending social events I might otherwise skip, and reaching out to old colleagues via email and video calls.
The first project matters. The research direction I choose in my first year will define how people perceive my independent work. I have been cautious about this, taking time to identify problems that are both interesting to me and strategically sensible. It has been tempting to jump on whatever is trending, but I think the wiser approach is to find problems where my specific training gives me a genuine advantage.
Physical health affects mathematical output. During my final PhD year, I let exercise and sleep slide. The effect on my research was noticeable. I am trying to correct this, running three mornings a week and enforcing a shutdown time in the evening. Mathematics requires sustained concentration, and that requires a body and mind that are not exhausted.
Looking Ahead
I do not know what comes after this postdoc. The academic job market is competitive, and the path to a permanent position is not guaranteed. I try not to think about it too much, focusing instead on doing good work and trusting that the rest will follow. Whether that trust is justified remains to be seen.
What I do know is that I am working on problems I care about, in a field that remains interesting to me, with tools that I spent years learning to use. That is enough for now.
If you are a PhD student reading this and contemplating the postdoc transition, my only observation is this: it is both harder and more rewarding than I expected, and for reasons I did not anticipate. The hardest part is not the mathematics. The hardest part is building a new life in a new place while simultaneously establishing yourself as an independent researcher. The rewarding part is the same thing.