In the course
Keep watching
10 videos · 4 h 7 min
Course · Yale
YaleCourses · Ramamurti Shankar · 2010
Ramamurti Shankar, author of a classic graduate textbook, gives one of the gentlest rigorous introductions anywhere: seven lectures from the double-slit experiment through measurement, the particle in a box, the time-dependent Schrödinger equation and the postulates.
Lecture · MIT
MIT OpenCourseWare · Allan Adams · 2013
The opening lecture of MIT's 8.04 Quantum Physics I (Spring 2013), in which Allan Adams uses thought experiments with measuring boxes to build superposition and uncertainty from scratch. Skip the first ten minutes of course logistics, then watch how a few simple box experiments force exactly the rules of this session: repeat a measurement and the answer stays put; measure an incompatible property and it is scrambled.
Lecture · MIT
MIT OpenCourseWare · Barton Zwiebach
Zwiebach contrasts classical superposition of fields with the quantum kind using single photons in a Mach-Zehnder interferometer, then states the rule this section builds on: measure a property on αA + βB and you never get anything in between, only a or b, with odds set by |α|² and |β|², after which the state is the one you found. When he says a photon is 'in both beams at the same time', translate it into this section's language (one definite state written as a sum of two path states), and catch his point at about 7:30 that the same vector can be written as a sum in many different ways.
Lecture · MIT
MIT OpenCourseWare · Barton Zwiebach
Starts at 7:55, where Zwiebach states the measurement postulate as this section does: the result is always an eigenvalue, its probability is |αᵢ|², the squared overlap with the eigenstate, and the state collapses to that eigenstate, so an immediate repeat gives the same value; rewind to the beginning to see how any state is expanded in eigenfunctions and why the |αᵢ|² add up to 1. Stay for 15:10, where he calls it 'a very strange postulate' that splits quantum mechanics into the realm of the Schrödinger equation and the realm of measurement, a preview of section 6.
Short · Washington University in St. Louis
Washington University in St. Louis
A three-minute university video on Kater Murch's group, who probed the role of measurement in the Zeno effects with an artificial-atom qubit, including a 'quasimeasurement' interaction that only disturbs it; Murch calls the results the first observation of the two Zeno effects on a single quantum system. It sharpens this section's lesson that what freezes a quantum state is a physical interaction, not anybody looking.
Lecture · Uppsala University
Uppsala universitet · Serge Haroche
Haroche, whose group ran the 1996 Paris experiment in this section, gives a public version of his Nobel talk 'Controlling photons in a box and exploring the quantum to classical boundary' (the Stockholm lecture itself is in the Lecture Hall). It starts at 40:10, where a single atom prepares a Schrödinger-cat state of light, followed at 42:37 by 'Fifty milliseconds in the life of a Schrödinger cat': the laboratory version of this section's question of how fast a superposition of distinguishable states fades.
Lecture · Caltech
John Preskill · 2021
The lecture from Caltech Ph/CS 219A Quantum Computation (John Preskill, 2021) that goes with Chapter 15. The whole course is in the Lecture Hall.
Course · MIT
MIT OpenCourseWare · Barton Zwiebach · 2013
The sequel: vector spaces and Dirac notation, the uncertainty principle done properly, the Heisenberg picture, two-state systems, tensor products and the addition of angular momentum. The natural next step once Unit 3 of this course feels comfortable.
Explainer · YouTube
The Science Asylum
Nick Lucid of The Science Asylum takes superposition back to its roots in ordinary wave physics and strips away the mystical talk that usually surrounds it. As you watch, test what you hear against this session's central claim: a superposition is one perfectly definite state written as a sum, and whether a state counts as a superposition depends on which measurement you have in mind.
Explainer · YouTube
Sabine Hossenfelder
A compact statement of the measurement problem from the theoretical physicist Sabine Hossenfelder, who explains why the measurement update cannot simply be derived from the Schrödinger equation. Her conclusion, that quantum mechanics therefore needs to be completed, is one position among several; chapter 22 lays out the others.