QUANTUM QNT

Quantum History Part 2: Feynman, Deutsch, Shor and Grover (1981 to 1996)

Updated | 4 min read | QUANTUM (QNT) community

1981: a famous hunch

At MIT's first Conference on the Physics of Computation in 1981, Richard Feynman argued that classical computers appear unable to simulate quantum systems efficiently, and sketched the basic idea of a quantum computer. His paper was published in 1982, and that year is conventionally treated as the start of quantum computing. Yuri Manin is reported to have suggested something similar independently. The logic was beautiful and simple: if nature runs on quantum rules, the best machine for studying nature might need to run on them too.

This is still one of the most hopeful ideas in the field. Simulating molecules and materials is a natural job for quantum hardware, as explored in medicine and materials.

1984 and 1985: security and universality

In 1984 Charles Bennett and Gilles Brassard showed how quantum effects could protect secret keys, the seed of quantum key distribution. In 1985 David Deutsch at Oxford described the first universal quantum computer, a model that can in principle run any quantum computation, in the way Turing's machine did for ordinary computers. The same year, Asher Peres pointed out the need for quantum error correction, an early hint of a problem that still dominates the field forty years later.

Deutsch's algorithm and its cousins from 1993 and 1994 (Bernstein and Vazirani, Simon) showed on paper that querying a black box with superposed inputs can reveal more than a classical query. They solved no practical problems, but they proved a point: quantum machines could be different, not just faster.

1994: Shor changes the conversation

Then came the shock. Peter Shor, working at AT&T Bell Labs, presented efficient quantum methods for factoring big integers and for discrete logarithms. A version posted on arXiv is dated 1995 and revised in January 1996, titled "Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer". The abstract notes that these two problems underpin several proposed cryptosystems.

That was the moment quantum computing stopped being a physics curiosity. Public key systems such as RSA rely on factoring being hard, and a large enough quantum computer would change that. Governments and banks started paying attention. You can read the full explanation in Shor's Algorithm Explained Step by Step and What Is RSA and Why Can Quantum Computers Break It. The same shock is why the world is now moving to new encryption, covered in The NIST Post-Quantum Process Explained.

Also look at the bright side: Shor's discovery gave the field its first undeniable reason to exist, and it triggered the funding and talent that built everything after.

1995 and 1996: fixing mistakes on paper

Many physicists in the mid 1990s doubted quantum computers could ever work, because quantum states are fragile and measuring them disturbs them. Bill Unruh voiced such doubts in 1994. The reply came quickly. In 1995 Shor proposed the first quantum error correction schemes, and in 1996 Andrew Steane designed another code. The key insight was that you can protect quantum information by spreading it over several physical qubits without ever reading it directly. This is the ancestor of the error correction and surface code work that dominates 2026 news.

1996: Grover and Lloyd

In 1996 Lov Grover, also at Bell Labs, published "A fast quantum mechanical algorithm for database search". The abstract says an item in an unsorted list can be found in about the square root of N steps, where a classical method needs on the order of N. It is a quadratic speedup, not an exponential one, and it is widely useful, as you can see in Grover's Algorithm Explained Step by Step. Also in 1996, Seth Lloyd showed that quantum computers could simulate quantum systems efficiently, giving Feynman's hunch a firm mathematical footing.

What this era taught us

Looking ahead

Next in the series: the first real qubits. For more on algorithms in general, see Quantum Algorithms Explained for Beginners.

Dates note: Shor's algorithm is commonly dated 1994 (the conference presentation) while the journal and arXiv versions are dated 1995 and 1996. Both appear in sources.

Sources and further reading

Reported as of 2026-10-09. Company claims are the companies' own unless a source says otherwise. Educational content only, not financial advice. The QNT memecoin is independent of Quantinuum Ltd and every other company, lab or government.

Frequently asked questions

What did Feynman say about quantum computers?

In 1981 he argued that classical computers appear unable to simulate quantum systems efficiently and proposed a basic model of a quantum computer. The paper followed in 1982.

Why was Shor's algorithm such a big deal?

It showed a quantum computer could factor large numbers and solve discrete logarithms in polynomial time, which threatens the public key cryptography behind RSA and related systems.

What is the difference between Shor and Grover?

Shor gives an exponential speedup for factoring. Grover gives a quadratic speedup for unstructured search. Both are real, and they matter for different reasons.

Share on X

Keep reading

All Quantum computing guides | Back to top | Search the site

Main pages: Quantum computing explained | Quantum and crypto | Companies | Quantum news | Glossary

QUANTUM (QNT) is the quantum sector memecoin on Solana. See the live chart, buys and burnt supply or read the token facts. Questions? Join the Telegram.