*This article, the video and the podcast accompany the Women of
Mathematics photo exhibition. You can download Nilanjana Datta's exhibition poster by clicking here. To see more profiles of female mathematicians and to find out more about the exhibition, see here. Photographs by Henry Kenyon.*

Watch the interview with Nilanjana Datta in this video!

Nilanjana Datta is a lecturer in quantum information theory at the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, and a fellow of Pembroke College.

** Plus:** How and when did you choose to do mathematics?

**Nilanjana Datta:** As far back as I can remember, from my early school days, physics and mathematics were my two favourite subjects. Well, I had two other passions, I also liked dance and creative writing. I still remember when I competed the Indian equivalent of GCSE, my English teacher who was a very enthusiastic Irish nun was rather upset that I chose to do science after that.

But once I started sixth form, it was absolutely clear to me that mathematics and physics were the subjects I wanted to study.

** Plus:** What's it like being a female mathematician?

**Nilanjana Datta:** Well, it is quite challenging because, as you very well know, we are the minority in this field. Surprisingly to me at least, [because] as far as university students are concerned, we are more of a minority in the Western world than back home where I come from in India, where we were half and half.

So numerous times, for example even during my research, I have been asked by various people, "Why do you do mathematics, why do you do physics?" Well, the answer was clear, because I love the subjects. But once I still remember when I expressed surprise that I was asked this question, I was told, "Don't you know? Mathematics is not feminine."

So there are these prejudices one has to fight against and often I've been mistaken for a secretary in the department. But, well, the challenge makes it all the more worthwhile.

** Plus:** What advice would you give to a young woman who is thinking about doing mathematics?

**Nilanjana Datta:** Yes, I would have a word of advice for them. If you like mathematics then forget the prejudices, ignore what others think. Just be passionate about it.

I have been asked many a time by young, female students whether it's possible to have a life, a family, children, as an academic doing mathematics. I would say yes, of course. It's completely possible. I have a family, I have a son.

I remember when my son was born some of my older colleagues, male colleagues, told me, "Oh, surely you're going to quit mathematics now." But of course I didn't. You have less time but that doesn't matter. We are women, we can multitask. You have shorter time but you can focus your thoughts and concentrate much better. It's even more satisfying.

So I would say that if this is what you want to do, then don't let anything stop you.

** Plus:** For you, what are the joys of doing mathematics and what are the challenges?

**Nilanjana Datta:** There are a couple of things that appeal to me about mathematics. One of them is that it's about pure reason, it's about absolute truth. There is no room for compromise or vagueness or varying points of view. When you prove a theorem then the statement of the theorem is a fact which nobody can refute, and that's wonderful.

Another thing is the simplicity and elegance of maths. We know that, using mathematics, one can often explain the complexities of nature by elegant and simple mathematical equations. This is very appealing to me.

Also another fact is about doing mathematics, the simplicity of it. We don't need a laboratory, expensive equipment or anything of the sort. All we need is a paper and a pencil and sometimes not even that.

I remember many a time sitting at the dinner table with my family secretly puzzling over some proof that I'd been stuck at and my husband saying, "You're not really with us, are you?"

The joy of mathematics is when you prove something. It is wonderful! It might be a very short-lived joy because then you're stuck at the next step, but it's still something I would not give up for anything else.

** Plus:** Could you explain your area of mathematics to somebody who doesn't know anything about maths?

**Nilanjana Datta:** Yes, I could try. The field I work on is called quantum information theory. Information theory by itself, which is often called classical information theory, is the mathematical theory of storage, processing and transmission of information.

The importance and relevance of this in our daily lives is obvious to everyone. All of us spend a considerable amount of time every day acquiring information, sending messages, processing information and there are more and more platforms or methods to do it using emails and texts and social media, laptops and mobile phones, etc.

What I work on is quantum information theory. So what's the quantum bit? That's the theory of these information processing tasks when you use quantum mechanical particles, like electrons and photons and atoms, as information carriers. Quantum mechanics is the fundamental theory of microscopic particles, particles on the atomic or subatomic level, where it replaces Newtonian mechanics. Because of the underlying quantum mechanics governing the dynamics of these information carriers, one often gets totally new effects which are not there in classical information theory. These new features can be exploited to perform certain information processing tasks much more efficiently, much more quickly and in an improved manner compared to classical information theory.

So that's my field of research. It's a highly interdisciplinary field. You'll find pure and applied mathematicians, physicists and engineers working in this field. It's very exciting, though my research is more focused on the mathematical aspects of it. *(You can read more about quantum information in these Plus articles.)*

** Plus:** Could you describe one of your favourite mathematical moments?

**Nilanjana Datta:** Oh, yes. Well, I remember one day I was invited to an international conference called TQC which was held in Tokyo in Japan. Unfortunately the time of the conference was during Cambridge term time and I was lecturing a course, so I did something really crazy. I went all the way there just for three days, and that was the stupidest thing to do. So I reached there totally jet-lagged, completely exhausted, stressed about my talk.

Then I remember attending one talk by a Japanese scientist and suddenly just at the end of the talk, the haze seemed to have cleared. I went out for my coffee break and I had one idea, just one little idea. Strangely enough, that little idea led me to the main field of my current research. In fact, we now have an annual conference which is based on this small field and my introduction to that field was through that little eureka moment way back in Japan, all those years back.

** Plus:** Thank you very much!