The story of quantum computing
A book-style walk from the first quantum puzzles to the machines you can run from this IDE: who had the idea, what they were trying to solve, and how each step made the next one possible.
Nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum mechanical.
Chapter 1 · The quantum puzzle (1900–1935)
- 1900· Max Planck
Energy comes in packets
To explain black-body radiation Planck assumed energy is exchanged in quanta E = hν. He thought it was a mathematical trick. It was the birth certificate of quantum physics.
- 1925–26· Heisenberg, Schrödinger, Born, Dirac
Matrices and waves
Heisenberg built mechanics from matrices; Schrödinger from a wave equation. Born showed |ψ|² is a probability, Dirac unified the two pictures and invented the bra–ket notation |ψ⟩ you see everywhere in this app. Every gate matrix here is Heisenberg's idea; every statevector is Schrödinger's.
- 1935· Einstein, Podolsky, Rosen · Schrödinger
Entanglement named
EPR argued that correlated particles made quantum theory incomplete; Schrödinger coined the word 'entanglement' (Verschränkung) in reply. The Bell state in the hero animation is exactly their thought experiment.
Chapter 2 · From physics to computation (1964–1985)
- 1964· John Bell
Bell's theorem
Bell proved entanglement cannot be explained by hidden local variables, turning a philosophical argument into a measurable inequality. Experiments by Clauser (1972) and Aspect (1982) confirmed quantum mechanics; the three shared the 2022 Nobel Prize.
- 1980–82· Paul Benioff · Yuri Manin · Richard Feynman
The idea of a quantum computer
Benioff showed a Turing machine could run on quantum mechanics. Manin and Feynman asked the sharper question: classical computers choke on simulating quantum systems (2ⁿ amplitudes), so why not compute with quantum systems themselves? The ideal_statevector simulator here meets that 2ⁿ wall; on this shared server simulators stop at 4 qubits.
- 1985· David Deutsch
The universal quantum computer
Deutsch defined the quantum Turing machine and gave the first algorithm where a quantum computer beats a classical one, later generalized with Jozsa (1992). You can run Deutsch–Jozsa from the examples gallery.
Chapter 3 · The algorithms that changed everything (1994–1997)
- 1994· Peter Shor
Factoring in polynomial time
Shor's algorithm factors integers exponentially faster than any known classical method, threatening RSA encryption. Its heart is the quantum Fourier transform (QFT) in the examples gallery. Governments started funding the field the next year.
- 1995· Shor · Steane · Cirac & Zoller · Barenco et al.
Error correction and the first blueprint
Shor and Steane invented quantum error-correcting codes, answering the objection that noise makes quantum computers impossible. Cirac and Zoller proposed the trapped-ion CNOT; Barenco et al. proved CNOT plus single-qubit gates are universal: the reason the IDE's palette is enough.
- 1996· Lov Grover
Quadratic search speed-up
Grover's algorithm finds a marked item among N in about √N steps. The 2-qubit Grover example finds |11⟩ in a single iteration with probability 1.
- 1997–98· Kitaev · Aharonov & Ben-Or · Chuang, Gershenfeld, Cory
Threshold theorem and the first qubits
The threshold theorem showed that if gate errors are below a constant, arbitrarily long computations are possible. The same year the first 2-qubit NMR experiments ran Deutsch's algorithm on real molecules.
Chapter 4 · Building the machines (1999–2019)
- 1999· Nakamura, Pashkin, Tsai (NEC)
The first superconducting qubit
A Cooper-pair box showed coherent oscillations for a few nanoseconds. Today's IBM transmons descend from it, with T1 and T2 a hundred thousand times longer.
- 2000· David DiVincenzo
Five criteria
Well-defined qubits, initialization, long coherence, a universal gate set, and measurement. Every hardware tab in this IDE reports against them: qubit count, T1/T2, basis gates, readout error.
- 2007· Yale (Koch, Schoelkopf, Girvin, Devoret)
The transmon
A charge-insensitive superconducting qubit that made coherence times jump. It is the qubit inside every IBM Eagle and Heron processor you can select in the Hardware tab.
- 2016–17· IBM
Quantum computing on the cloud · Qiskit
IBM put a 5-qubit processor online for anyone to use, then released Qiskit, the open-source SDK this whole application is built on.
- 2018· John Preskill
The NISQ era
Noisy Intermediate-Scale Quantum: 50–1000 qubits without full error correction. Variational algorithms (VQE, QAOA in the examples) and error mitigation and circuit cutting (this IDE's Phase 7) are the tools of this era.
- 2019· Google (Arute et al.)
Quantum advantage claimed
Sycamore, 53 qubits, sampled random circuits in 200 seconds; Google estimated 10 000 years classically. Classical teams later shrank that gap, but the race was on.
Chapter 5 · Scale and correction (2021–today)
- 2021–23· IBM
Eagle (127) and Heron (133)
Eagle crossed 100 qubits with a heavy-hex lattice; Heron introduced tunable couplers and CZ gates with lower crosstalk. Their fake twins are the fake_* backends you simulate against.
- 2023· Harvard/QuEra · IBM
Logical qubits and 'utility'
Neutral-atom arrays ran 48 logical qubits with error-corrected operations; IBM showed a 127-qubit Ising simulation beyond brute-force classical methods, using error mitigation.
- 2024· Google
Below threshold
Willow demonstrated that a larger surface code (distance 7) had a lower logical error rate than a smaller one: the first time error correction clearly scaled the right way, 30 years after Shor's proposal.
- 2025–26· Qiskit 2 · IBM Heron r2/r3 · the whole field
Where you are now
156-qubit Herons, fractional RZZ gates, Qiskit 2 with the C-based transpiler, and open circuit-cutting tools. QubitLab sits on top of all of this: every job you submit from the IDE travels this entire history in a few seconds.
Dates and attributions follow the standard histories (Nielsen & Chuang; Preskill's lecture notes; the 2022 Nobel citation). Where several groups contributed, the first published result is named.