Wednesday, October 26, 2011

Physics Pieces (Part 2)

Another exciting week has gone by, and the current week is unrelentless in seeking to outdo the last.

It's just mid-week and already David Weiss from Penn State gave us a summary of the various cold atom experiments going on in his lab - ranging from quantum computing on a 3-d lattice to a quantum version of "Newton's cradle" and a search for the electron dipole moment.

Fiona Burnell, a post-doc in our group, gave an informal presentation on a toy model for fractional topological insulators. Useful ideas to help me navigate the zoo of condensed matter systems out there. She did her PhD at Princeton under Shivaji Sondhi and had started her studies there while I was still there as an undergraduate.

But the real focus of this post was last week.

Alessandro de Silva from ICTP Trieste spoke about quantum quenches, studying the behaviour of systems quickly thrown from an equilibrium state to another via a non-equilibrium process.

Chris Hooley from St Andrews gave an entertaining lecture, based on some initial research into the use of complex temperatures for the thermodynamic partition function. It was useful for me as he spent a lot of time motivating the discussion and talking about quantum critical points.

David Nelson from Harvard gave a very accessible presentation on the packing problem on a curved surface. Very nice simulations and visuals for a practical and mathematical topic, and actually had everyone in the audience looking at a golf ball (the distribution of the dimples on the surface is related to how viruses arrange their capsomeres).

Lev Ioffe from Rutgers talked about quantum coherence, and what I really enjoyed were the introductory graphics with spherical cows and the philosophical idea that if the environment itself is quantum, then how does quantum decoherence set in? So it's like Schrödinger's cats looking at Schrödinger's cats.

With the complement of courses and problem sets, I am slowly but surely progressing on the path of understanding nature better!

Tuesday, October 25, 2011


It's getting so cold in Oxford. And it's going to get colder.

On hibernation, somehow the upgrade to Ubuntu 11.10 broke hibernation, which was working when I was using Ubuntu 11.04. Or perhaps it was from my fiddling with the fglrx driver for AMD graphics.

Got a message that there wasn't enough space, which was weird. Followed the instructions on making a new swap partition work for hibernate, and even tried to create a 10 GB swap partition, but was still being told that there wasn't enough memory! It only worked intermittently when I had freshly booted in.

Stumbled upon this forum thread which led me to the answer.
  • Checked /var/log/syslog which showed that the hibernation image needed more pages than available in the swap partition. 
  • The magic fix is "echo 0 > /sys/power/image_size", which was set at too high a value on my system. 
  • As this value is reset across reboots, I embedded this line at the start of /usr/sbin/pm-hibernate.

Tuesday, October 18, 2011

Physics Pieces (Part 1)

A quick review of the week gone by...

A talk given by Olga Sikora (who worked in Nic Shannon's group in Bristol) was on spin ice and mentioned that frustration can occur as "charge frustration" as well. Professor Shannon is based in Oxford this year, and is subsequently headed to the new Okinawa Institute of Science and Technology next year.

A talk by Shivaji Sondhi presented a very interesting description of quantum liquids by considering the vortex structure induced in superfluids when coupled with real-space rotation in a bucket. Professor Sondhi was my advisor for my very first research project on the Ising model during Junior Year at Princeton.

A talk by Mark Newman on networks. Excellent for showing the application of physical insight (mainly statistical physics) into problems such as social networks, such as a simple proof of why it usually is that your friends on average have more friends than you (Ref). Professor Newman is a prolific author and did his DPhil at Oxford, co-supervised by Robin Stinchcombe and David Sherrington.

Monday, October 17, 2011


The first real rain since we arrived. Good thing it's nighttime and we're indoors sleeping.


First bicycle accident today. The form factor of a stationary car fluctuates by the size of a door when there is at least one occupant.

Sunday, October 16, 2011

Ubuntu 11.10

Just upgraded to Ubuntu 11.10, what I appreciate is good support for laptop hardware. I even get two-finger scroll with the touchpad out of the box.


The process of becoming a member of the university, tied to past and future generations by a ritual of Latin pronouncements.

Tuesday, October 11, 2011

ring flinger

parting the moss
reaching an unadorned hand
into the cold water

turning up
a bottle cap
soiled in the murky depths

a moment ago like a fish
splashing off a fat worm

fingers now in again
caressing the river bed
for the missing ring
sensation running

backwards in time
an anchor sinking into the cherwell
flashing back to the jeweler's

and tossed
upon the dreaming spires