Recent content by Lapetude

A nice discussion of the density operator for a qubit can be found here: http://www.vcpc.univie.ac.at/~ian/hotlist/qc/talks/bloch-sphere-rotations.pdf

Sorry I just found https://www.physicsforums.com/showthread.php?t=306228 which is what I'm after. fysics4fun made it clear: "mpkannan makes it clear- you must look at everything in context before deciding the signs on everything. A question like "what is the sign on work" is too vague...

Homework Statement I am wondering about the following conventions: The work done by the gas is positive if the gas expands, and negative if it is compressed. Conversely, the work done on the gas by external force (e.g., a moving piston) is positive for compression, and negative when...