Quantum Physics I

created_at: 2021-08-23

I began learning quantum mechanics with Professor Allan Adams on MIT OpenCourseWare! This will be an ongoing post about interesting things I learn, as a way to share a computer scientist's perspective on quantum physics as well as to hold myself accountable in finishing the course.

The miracle is not that electrons behave oddly. The miracle is that when you take $10^{26}$ electrons, they behave like cheese! 🧀

The first lecture taught me something fundamental about the term superposition. As I used quantum computers, I thought about the qubits as being both 0 and 1 while in superposition; however, this is false. The qubit is in no meaningful state: not 0, not 1, not both, and not neither.

In the second lecture, this idea of superposition is again reiterated by the famous double-slit experiment, where an electron neither passes through the top nor bottom slits, neither both nor no slits. Contuining to experimentally demonstrate quantum properties, Professor Adams then proved Bell's Inequality very simply as $P(a \cup \overline{b}) + P(b \cup \overline{c}) \geq P(a \cup \overline{c})$. Perhaps unsurprisingly at this point, electrons' angular momenta in the x, y, and z axes, which are either up or down, do not abide by Bell's Inequality. However, this is very surprising, because simple logic and integers must be flawed at a fundamental sense to not accurately describe quantum properties.

I'm tempted to take a course now, because doing problem sets for a course designed to be taken in-person is tedious. I also want a certificate😮‍💨. If the OpenCourseWare site is down, click here to download the lecture materials.