Quantum Essentials
The course
Quantum Essentials: an introduction and 17 chapters in four modules. Each chapter from 1 to 16 has three optional pages: a real-world case, a step deeper and a people story.
Module 1 · How quantum works
01 Why does the small world come in steps?
- 1a · Real-world case How does a laser work?
- 1b · A step deeper Why don't atoms collapse?
- 1c · People story Einstein's Nobel Prize was for light quanta, not relativity
02 What is superposition, really?
- 2a · Real-world case Spin at work: how MRI scanners use it
- 2b · A step deeper The Stern-Gerlach experiment: the experiment that revealed spin
- 2c · People story Stern, Gerlach and the cheap cigar that made the result visible (1922)
03 What does measuring actually do?
- 3a · Real-world case Schrödinger's cat, properly explained
- 3b · A step deeper Why qubits lose their state: decoherence in the lab
- 3c · People story Schrödinger's cat began as a joke aimed at the theory (1935)
04 What is interference, and why does everything depend on it?
- 4a · Real-world case The double slit, one particle at a time
- 4b · A step deeper Interferometers that measure the universe (LIGO)
- 4c · People story Thomas Young: the polymath behind the double slit, who also helped decode the Rosetta Stone
- 5a · Real-world case Teleportation: what it is and what it isn't
- 5b · A step deeper Bell's test, step by step
- 5c · People story John Bell: an accelerator physicist whose side project won others the 2022 Nobel
06 What do the interpretations say, and how does popular culture show them?
- 6a · Real-world case Multiverses on screen: what Everything Everywhere All at Once and Marvel get right and wrong about Many-Worlds
- 6b · A step deeper Five more answers: QBism, relational, consistent histories, ensemble and superdeterminism
- 6c · People story Hugh Everett: he invented Many-Worlds, left physics, and his son became E of the band Eels
Module 2 · Quantum computers
07 What is a qubit, and what does a quantum computer actually do?
- 7a · Real-world case Shor's algorithm in pictures (factoring 15)
- 7b · A step deeper Grover's search and quantum simulation
- 7c · People story Feynman's 1981 talk that launched quantum computing
08 Why are qubits fragile, and how do we fix that?
- 8a · Real-world case The surface code: error correction on a grid
- 8b · A step deeper Logical qubits today: the milestones so far (dated)
- 8c · People story Peter Shor and the error-correcting code many thought impossible (1995)
09 How do you build a qubit from circuits, ions and atoms?
- 9a · Real-world case Inside a superconducting quantum computer (the dilution refrigerator)
- 9b · A step deeper Atoms and ions held by light and fields
- 9c · People story Clarke, Devoret and Martinis: 1980s Berkeley experiments, the 2025 Nobel, and today's superconducting qubits
10 How do you build a qubit from light, silicon, Majoranas and annealers?
- 10a · Real-world case Computing with light: photons, fusion and loss
- 10b · A step deeper The Majorana debate, both sides (dated)
- 10c · People story Terry Rudolph: Schrödinger's grandson co-founded PsiQuantum (and co-wrote the PBR theorem)
11 Which quantum computing approach is winning?
- 11a · Real-world case Reading a roadmap: promised against delivered
- 11b · A step deeper Benchmarks, and why qubit count misleads
- 11c · People story John Preskill: the physicist who named "quantum supremacy" (2012) and "NISQ" (2018)
Module 3 · Sensing and secure communication
12 How does quantum sensing work, and where is it used today?
- 12a · Real-world case Atomic clocks, from GPS to redefining the second
- 12b · A step deeper UK case studies: gravimeters and wearable brain scanners
- 12c · People story Louis Essen and the first caesium atomic clock (NPL, Teddington, 1955)
13 How does quantum keep secrets, and will it break today's encryption?
- 13a · Real-world case How RSA and elliptic-curve keys work (toy RSA)
- 13b · A step deeper Post-quantum cryptography: the new standards and the deadlines
- 13c · People story Clifford Cocks: he invented RSA in secret at GCHQ in 1973, and the world found out in 1997
Module 4 · Where we are now, and the finish
14 What can quantum computers do today, and what's still to come?
- 14a · Real-world case Chemistry and materials: the strongest long-term case
- 14b · A step deeper Quantum advantage claims so far, graded
- 14c · People story Charles Townes and the park-bench idea that led to the laser
15 Who is building quantum technology, and where is the money going?
- 15a · Real-world case The UK quantum landscape
- 15b · A step deeper Quantum jobs and skills: who is hiring, and for what
- 15c · People story Oxford Ionics: from an Oxford lab record to a billion-dollar sale
16 How do you tell quantum hype from the real thing?
- 16a · Real-world case Famous quantum hype stories, and what really happened
- 16b · A step deeper How to read a quantum press release
- 16c · People story Scott Aaronson, the professor who became quantum computing's best-known hype checker