Problem of mentioning the department affiliated with PhD degrees A newbie here :)

I am currently a PhD student in a computer science program. My research interest is about quantum information science. Back then, I also got accepted into a Physics PhD program, but I decided to join my current department because the project is much more interesting.

Here is my problem: when people ask me, "Hey, so what are you doing in grad school?" , I feel quite uncomfortable to mention that I am doing a degree in "Computer Science". Don't get me wrong. I love computer science. But I prefer to be regarded as a Physics person rather than a CS person (actually, I am doing a lot of theoretical quantum physics for my thesis). My feeling is that, the name of the department/degree ALONE doesn't do me justice in telling other about my research interests and experiences.

Funny enough, my boyfriend is also suffering from the same problem. He is in the same CS department with me, but focusing on computational biology. His plan is to attend medical school after his PhD, so he usually shows a tremendous amount of angst when being asked the same question. People often joke about his decision, like "So why an IT guy like you suddenly wants to go to med school?". The poor guy has spent quite a lot of time to do wet labs, and is drafting a thesis with 50% bio and 50% CS components, so I can tell that he really hates when people calling him an "IT guy". While I understand that doing a bio-related doctoral research is a very logical transition for him to med schools, the name of the department alone is causing the confusion that he has abruptly changed his interests into medicine, rather than planned for it ahead.

My question is, what is the best way in our cases to "market" our research focus and experiences to other people? Should it be:


Ms.Catwoman, PhD in Computer Science 
Ms.Catwoman, PhD in Quantum Information, or
Ms.Catwoman, PhD in Computer Science with special focus on Quantum Information?


Thanks for the answers!
My question is, what is the best way in our cases to "market" our research focus and experiences to other people? 


Marketing is all about knowing your audience. And thus you may market your PhD to different audiences in different ways.

If you're talking to a person on the street, you could say "PhD in Computer Science". 

If you're talking to a Computer Scientist, you could say "PhD in Quantum Information". 

If you're talking to a specialist in Quantum Information, you could say "PhD in X, Y &amp; Z" where X, Y and Z are detailed topics.

The truth of the matter is that a PhD is a PhD. Officially speaking, there's no such thing as a "PhD in ...". So for the given person in front of you, try to communicate the area of your PhD as best as you can.

And as for the "IT guy" stuff, if that's how they chose to stereotype what you are doing, then that's their problem, not yours/your boyfriends.