My interview experience at TIFR, Hyderabad- Yash Sarda

Hi I’m Yash. I was called for the interview at TIFR-H via my JEST score on 13th June for Int-PhD. The institute seemed to be located in a remote area. But heck, it’s the same with almost every institute I’ve been to (except tifr-m :)). I take a quick a look around and head straight to the Auditorium. The staff and the professors were welcoming and friendly.
After verification I was sent to the interview room.
I had to wait for an hour outside the room before they called me in. I had four professors on my Panel. Prof Surajit Sengupta, Prof Kabir Ramola, Prof Karthik V Raman and Prof Pranav Shirhatti.

Interview started with them asking about my background in Physics and how much Physics have I studied since I’m a Computer Science student. I honestly told them that I’ve done a year of Physics during undergrad and 6 months coaching in Delhi. They were very warm and comforting, occasionally exchanging jokes.

So they started with asking easy questions in topics of my choice(QM).

Q1) I was asked to draw graph of excited states in 1D harmonic oscillator. Easy question. I started drawing the first state, and that’s where it went downhill for me. The professors disagreed and told me to draw the next state, and I drew the next state which was again wrong. I was startled.
They told me to write Schrodinger’s equation. I did. Next they gave me a wave equation and told me to plug it in the SE. I was making a lot of silly mistakes in differentiation(surprising I know) and rearranging terms. It only added more pressure to my mind. I made around 8-10 silly mistakes (no exaggeration), but they were extremely patient with me. With a lot of corrections, they made me derive Energy of ground state. Then I was told to draw the graph of wave equation which I did (thankfully without any mistake). They looked at me and pointed that this was where I was making mistake. I got blank for a few seconds and then came the eureka moment. I realisd my mistake.
The wave equation given to me was Ae^(-x^2) and energy was 0.5hw/2pi. I realised that initially, I had started drawing from first state and just magically somehow forgot about ground state. Corrected the mistake and they were satisfied.

Q2) A.They told me to calm down and asked to find out expectation value of x in ground state of HO. As soon as I started solving Prof Kabir interrupted and asked whether this can be done without calculation to which I said yes it’s zero since it’s an odd function. They agreed.
    B. Find expectation value of x^2 in ground state of HO. I solved it using gamma integral but made a silly mistake in limits which they pointed and corrected.

Q3) Prof Kabir asked whether I’m comfortable with Stat Mech to which I told that’s my weakest. Prof Karthik then started with waves. An electron revolves around a positively charged nucleus. A wavefront hits this configuration, what would happen?
Till date I don’t what’s the answer to this question so if anyone is able to solve, please answer in the comment section. I answered the electron would jump to an excited state but the prof interrupted and said what would happen classically.
I wrote T.E(for electron) = 0.5mv^2-kq1q2/r since it gains energy and nucleus doesn’t move. I saw disagreement on their face, then I was directly given V=0.5kx^2 for this system and was told to find equation of x.
I found force and solved the second order DE, they seemed to agree.

Q4) Next topic of interest, I told CM. They asked me to draw graph of terminal velocity in fluids and explain, I did and they seemed to agree.

Q5) I was asked to write formula of stoke’s law. One thing I’ve consistently and successfully skipped since 12th std is  stoke’s law. Never thought it’d haunt me at his point of my life. I told them I didn’t know.And we all know what happens next. Yes they made me derive it. I just needed a small hint and the rest, derived it on my own.

In the end, they seemed pleased. Prof Kabir had encouraging words for me.

After the interviews, it was time for lab visits. I’m not into condensed matter physics but for someone who is into it, this place is a treat. They have pretty high tech and high end equipments. The labs are huge and they have variety of experimental setups imported from the U.S etc.

Result:- Not selected (HA-HA)