临时抱佛脚。

If you weigh something to find the weight, do you heigh something to find the height?


When you read the above sentence, in your inner dialogue, does "heigh" rhyme with "weigh" or does it rhyme with "why"?

Random thoughts:

If the person who is paid by a "payer" is called a "payee", a person who is tutored by a "tutor" is called a "tutee", is the dough baked by a "baker" called a "bakee"? The cigarette smoked by a "smoker" called a "smokee"?

Though I guess there isn't much point to give them names like that, since the terms like "payee" and "tutee" is meant to indicate to people (who already have a lot of other roles) what roles they are currently assuming, whereas a cigarette is usually assuming the role of being smoked and a lump of dough is usually assuming the role of being baked. So "cigarette" and "dough" are probably sort-of equivalent to "smokee" and "bakee".


Some literature has said that quantum entanglement is a resource, but I think it's kinda iffy. Unlike energy, there isn't a one-size-fits-all method to quantify it. I remember Prof Kwek was looking for a lay-man's analogy to measures of quantum entanglement - how there are so many different definitions, how the usefulness of each definition depends on the application the quantum states are associated with, and how different definitions may not agree with with other about whether one state is more entangled than another. Yet, measures of quantum entanglement are also not completely arbitrary, because there are some quantum states that are generally agreed upon to be maximally entangled and some that are completely un-entangled, which most (I dare not say all since I don't know all of them) measures of entanglement would indicate.

His first analogy was happiness, but he felt that it was too un-physical and imprecise. His second analogy was entropy (for example, Renyi entropy isn't just one single definition, but a definition that depends on some parameters, and these parameters depend on the application). I don't understand Renyi entropy at all, so I can't really appreciate whether his analogy was particularly apt. But now that I think about it, all the above characteristics remind me of measures of intelligence. There are various measures of intelligence, each of them useful for different purposes and different scales may not agree on whether one guy is more intelligent than another. But intelligence isn't completely arbitrary either, since there are some abilities that are generally recognised to be crucial indicators of intelligence, so surely a hypothetical person who gets a perfect score on a particular test item that tests this ability (maybe a what-pattern-comes-next test? I don't know) would be given high intelligence scores on most measures of intelligence (except maybe the more differentiated measures like the sub-scales of multiple intelligences).

Yay! So, next time someone asks me "what have you been doing for the past six months" I would have a nice reply. "I've been studying measures of quantum entanglement, which is somewhat iffy like measures of intelligence, but not quite."


What if Bell's inequality is tested in a way that the measurements are made in different inertial frames moving at relativistic speeds? Since simultaneity is relative, from one frame it would appear as though the measurement in say, Alice frame causes the wavefunction collapse and determines the quantum state that can be measured by Bob, while in Bob's frame it could appear otherwise. A simple way to reconcile this could be to state that that Alice would measure and what Bob would measure are both predetermined from the start, but Aha! this would cause the Bell's inequality to be satisfied even at Bell's test angles with maximally entangled states! Maybe there really isn't a problem with this scenario, but I'm kinda lazy to think about it now.

Just wondering about the first two lines of 林俊杰's 曹操...

First line:
不是英雄, 不论三国

Since a conditional statement is equivalent to the converse of its inverse, it can therefore be rewritten as such:
P1: 论三国的都是英雄.

Second line:
若是英雄怎么能不懂寂寞

This is clearly a rhethorical question, which means:
P2: 英雄都是寂寞的.

We are thus forced to conclude that:
C: 论三国的都是寂寞的.


Just sayin'.

Some reflections on my "work" at NUS, Centre for Quantum Technologies.

I hadn't realised it then, but coming up with something there is quite a difficult thing to do. I'm not sure if those people that my prof had previously recruited before they started uni had produced anything, but it is not a nice feeling to hang around at a place for five months without much idea of what's going in. I guess an analogy would be like being employed by a greek company in greece, with all the books(except maybe one) that teach greek also written in greek.

To be more specific, my journey started with my prof asking me to do the exercises in Griffith's Intro to QM (or as the taiwanese grad student would call it, the 猫书), and learning about Perez-Horodecki's criterion for separable states. Then he taught me about pure states and mixed states. One week later, I was given one 4 page paper, which supposedly requires me to understand a 90 page review paper on quantum entanglement before I could appreciate it. I got stuck on the fifth page, i.e, when the first mathematical equation appeared (the definition of a separable state). It was written in Dirac's notation and made use of the tensor product symbol. It was around that time when I started chapter 3 in the 猫书, where Dirac's notation was taught in one page. (I don't think I'm the only one who can't learn Dirac's notation explained in one page) But there wasn't any mention of tensor products, so I tried to learn about it on Wikipedia, which was a really bad idea, since I followed every link, hoping to be able to understand this one by following the next... but it somehow got into group theory and abstract algebra. Having learnt nothing about tensor products (except the fact that it's a bilinear map), I tried to see if it was related to tensors. I didn't manage to learn much about tensors. After two weeks of struggling with Dirac notation and the elusive tensor product, I asked my prof what a tensor product is, and he gave a really simple explanation. Lesson learnt: don't know, ask. Around this time, a teacher happened to ask me how I was doing, and he recommended me Susskin's lecture and Cohen-Tannouji's textbook, which were really helpful.

Around this time, my prof asked me to help him write some lecture notes for grad students, and I got really excited, cos it made it sound like I was very zai. I came up with the first set of lecture notes, but honestly, I don't think I really understood the material well enough to write notes about it, so my notes were quite crap. Perhaps his intention was to make me think hard about what I was learning. But a nice side effect was that I got introduced to LaTeX, which is NOT user friendly at all.

Just when I thought I could be helping those after me to learn about quantum information, I realised that Nielson and Chieng's textbook of quantum information was better than what I could ever write in the next few months, so the notes I wrote was quite redundant. Also, in the last week there, I realised that measures of quantum entanglement had to be associated with some application for it to have any physical meaning, and so far I had learnt nothing about the application. There have been a few instances when people asked me "can you explain in lay-man's terms what is it that you do?" and I couldn't. At the end of it, I didn't even understand half of that 90 page review paper. That sucks.

But oh well. At least I learnt some LaTeX and linear algebra. And I finally have some idea of what a matrix determinant is.

令堂甚肥 -  具落雁之地心引力矣！