Appendix J: A Timeline
Dates for the results this book relies on. Chapter numbers point to where the book measures or uses each one — this is a reading path as much as a chronology.
Entries after roughly 2023 are close enough to the present that their significance is genuinely uncertain. They are included because the book cites them, not because history has settled.
Foundations (1980–1994)
| Year | Event | Ch. |
|---|---|---|
| 1980–82 | Feynman and Manin argue quantum systems need quantum computers to simulate | 1, 36 |
| 1982 | No-cloning theorem (Wootters–Zurek, Dieks) | 38 |
| 1984 | BB84 (Bennett–Brassard) — quantum key distribution | 38 |
| 1985 | Deutsch defines the universal quantum computer | 1, 20 |
| 1992 | Deutsch–Jozsa — the first exponential black-box separation | 20 |
| 1993 | Teleportation proposed (Bennett et al.) | 9 |
| 1994 | Shor's algorithm — polynomial-time factoring | 23 |
| 1994 | Goemans–Williamson — 0.87856 MaxCut approximation | 24, 37 |
★ Note the last two. They are the same year, and Chapter 37 measured QAOA losing 0–6 to the classical one. The algorithm quantum computing is most feared for and the algorithm that beats its near-term optimizer were published simultaneously.
Error correction and structure (1995–2000)
| Year | Event | Ch. |
|---|---|---|
| 1995 | Shor's 9-qubit code — error correction is possible | 25 |
| 1996 | Steane code; CSS codes | 25 |
| 1996 | Grover's algorithm — quadratic unstructured search | 21 |
| 1997 | Threshold theorem (Aharonov–Ben-Or, Knill et al.) | 15, 25 |
| 1997 | Simon's algorithm — the template for Shor's | 20 |
| 1998 | Gottesman–Knill — Clifford circuits are classically simulable | 11, 19 |
| 1998 | First NMR demonstrations of small algorithms | 1 |
| 2000 | Kitaev's surface code framework matures | 25 |
The long build (2001–2015)
| Year | Event | Ch. |
|---|---|---|
| 2001 | Shor's algorithm factors 15 on NMR | 23 |
| 2002 | Bravyi–Kitaev fermionic mapping | 36 |
| 2005 | Aspuru-Guzik et al. — quantum chemistry via phase estimation | 36 |
| 2005 | Magic state distillation (Bravyi–Kitaev) | 15 |
| 2008 | HHL algorithm for linear systems | 32 |
| 2012 | Fowler et al. surface-code roadmap — the overhead numbers | 15, 25 |
| 2012 | Seeley–Richard–Love on Bravyi–Kitaev for electronic structure | 36 |
| 2014 | VQE (Peruzzo et al.) — designed for devices that cannot run QPE | 24, 36 |
| 2014 | QAOA (Farhi–Goldstone–Gutmann) | 24, 37 |
| 2015 | Aaronson, "Read the fine print" — the input/output problem stated plainly | 32, 40 |
NISQ (2016–2022)
| Year | Event | Ch. |
|---|---|---|
| 2016 | IBM puts a 5-qubit device on the public cloud | 1, 12 |
| 2017 | Reiher et al. FeMoco resource estimate | 36 |
| 2018 | Preskill names the NISQ era | 1, 40 |
| 2018 | Barren plateaus (McClean et al.) | 16, 32 |
| 2019 | Google's Sycamore supremacy claim; disputed almost immediately | 14, 20 |
| 2019 | Quantum Volume proposed as a device metric | 30 |
| 2020 | Classical shadows (Huang–Kueng–Preskill) | 35 |
| 2020 | Zhou et al. on QAOA angle transfer | 37 |
| 2021 | Stilck França–García-Patrón — noise limits on variational optimization | 37 |
| 2021 | Von Burg et al. — a much improved catalysis estimate | 36 |
| 2022 | Huang et al. — proven advantage in learning from experiments | 35, 40 |
| 2022 | Gonthier et al. — measurement as the roadblock in chemistry | 36 |
| 2022 | SIKE broken classically — a NIST post-quantum candidate falls | 38 |
| 2022 | Schuld–Killoran — is advantage the right goal for QML? | 32, 40 |
Recent (2023–2026)
| Year | Event | Ch. |
|---|---|---|
| 2023 | Hoefler–Häner–Troyer — disentangling hype from practicality | 40 |
| 2023–24 | Below-threshold surface code demonstrations — adding qubits reduces logical error | 25, 40 |
| 2024 | NIST standardizes ML-KEM, ML-DSA, SLH-DSA (FIPS 203/204/205) | 23, 38 |
| 2024 | Qiskit 1.0; BackendV1 deprecated |
A, C |
| 2025 | Qiskit 2.0 — qiskit.pulse removed |
31, A, C |
| 2025–26 | Devices past 1,000 physical qubits; no change to this book's scorecard | 39, 40 |
★ That last row is the one to sit with. Qubit counts rose by an order of magnitude across this book's writing, and not one of Chapter 40's six head-to-head comparisons changed hands. Width was never the binding constraint — Chapter 15's T-gate overhead, Chapter 24's shot budget, and Chapter 39's queue all were, and none of them is measured in qubits.
What to watch
Four things whose movement would actually change the scorecard:
- Below-threshold error correction at scale. The 2023–24 demonstrations are the most important experimental progress in the field, and they are on the thing that gates everything else.
- A real-time decoder meeting the latency budget. Chapter 40 §40.1's highest-demand skill.
- An instance family where a classical guarantee is tight and quantum does better. Chapter 37 §37.9 notes none has been demonstrated on hardware.
- A learning task with quantum input and a demonstrated separation on real data. Chapter 35's surviving case.
Not on the list: qubit count, and any announcement whose headline number is one.
See also: Chapter 1 (the landscape), Chapter 40 (what it adds up to), Appendix H (the ecosystem this produced), the bibliography (every source cited).