In the course
Keep watching
10 videos · 3 h 26 min
Lecture · IBM Quantum
Qiskit · John Watrous · 2022–25
The lecture from IBM Quantum Understanding Quantum Information & Computation (John Watrous, 2022–25) that goes with Chapter 15. The whole course is in the Lecture Hall.
Explainer · Perimeter
Perimeter Institute for Theoretical Physics · Katie Mack · 2023
A short episode from Perimeter Institute's Quantum 101 series with Katie Mack. Watch it alongside Chapter 15.
Series · Perimeter
Perimeter Institute for Theoretical Physics · Katie Mack · 2023
Ten five-minute episodes hosted by the cosmologist Katie Mack: duality, quantization, uncertainty, superposition, entanglement, probability, tunnelling and quantum computing. The friendliest possible on-ramp, and a quick refresher before any chapter.
Course · IBM Quantum
Qiskit · John Watrous · 2022–25
The clearest modern course on quantum information, from IBM Quantum's John Watrous: single and multiple systems, circuits, teleportation and superdense coding, Shor's and Grover's algorithms, density matrices and error correction. Mathematically honest without being heavy.
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.
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.
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.
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.
Demo · YouTube
Orion Lawlor
A 90-second tabletop demo: two crossed polarizers block the light, and a third at a diagonal angle lets light through again, but only when it sits between them, not before or after. Watch it right after this section's three-filter paragraph and narrate each filter as a measurement in a new basis; the uploader's notes also point to Dirac, who opened his 1930 textbook with the polarization of single photons.