Quantum Computing Explained
What is quantum computing?
An ordinary computer stores information as bits, each either 0 or 1. A quantum computer uses qubits. A qubit can be in a combination of 0 and 1 at once, called superposition, and qubits can be linked so that their results are correlated, called entanglement. A quantum algorithm arranges these states so that wrong answers cancel out and right answers reinforce, which is called interference. A quantum computer is not a faster version of a laptop. It is a different tool that is only better at specific kinds of problems. IBM gives an introduction in its quantum computing overview.
Go deeper: what is quantum computing, what is a qubit, superposition and entanglement. You can also try the one qubit simulator in the qubit guide.
What are quantum computers used for?
| Area | Why quantum could help | Status |
|---|---|---|
| Chemistry and materials | Molecules obey quantum mechanics, so quantum machines can simulate them naturally. | Small demonstrations. Large useful results need error correction. |
| Cryptography | Shor's algorithm factors large numbers and solves the discrete logarithm problem efficiently, which threatens RSA and elliptic curve keys. | Needs a large fault tolerant machine that does not exist yet. |
| Search and optimisation | Grover's algorithm gives a quadratic speedup for unstructured search. | Modest gain. Real world advantage is unproven for most problems. |
| Sensing and timing | Quantum sensors measure tiny changes in fields and time. | Already used in some products. |
| Machine learning | Proposed speedups for some tasks. | Mostly unproven. Classical methods are often as good. |
See quantum computing myths and the types of quantum computers.
Where does quantum computing stand today?
Current machines are often described as noisy intermediate scale quantum (NISQ) devices, a term from physicist John Preskill (arXiv:1801.00862). Qubits are fragile, so errors build up. The fix is quantum error correction, which spreads one reliable "logical" qubit across many physical qubits.
- In 2024 Google Quantum AI reported error rates that fell as the code grew, a key milestone ("below threshold"), in arXiv:2408.13687. See the Willow guide.
- IBM publishes a public quantum roadmap that targets a large fault tolerant system by the end of the decade. Roadmaps are plans, not guarantees. See the IBM roadmap guide.
What does quantum computing mean for cryptography and crypto?
Peter Shor showed in 1994 that a quantum computer could break RSA and elliptic curve cryptography (arXiv:quant-ph/9508027). A 2025 estimate by Google researcher Craig Gidney found that 2048 bit RSA could be broken with fewer than one million noisy qubits in under a week (arXiv:2505.15917), far more than any machine has today. Many blockchains, including Bitcoin and Solana, use elliptic curve signatures, so they will need to move to post-quantum signatures before such a machine exists.
NIST finalised its first post-quantum standards, FIPS 203, 204 and 205, in August 2024 (NIST announcement). Its draft transition plan, NIST IR 8547, proposes retiring today's quantum vulnerable algorithms by 2035. Attackers could also store encrypted data now to decrypt later: harvest now, decrypt later.
Read will quantum computers break Bitcoin and Solana, post-quantum plans for Ethereum and Solana and government deadlines.
How does this relate to QNT?
QNT is a community memecoin with a quantum theme. It is not a quantum computing project and it is not quantum resistant by design. Holding it has nothing to do with owning quantum technology. See What is QNT?. It is not affiliated with Quantinuum Ltd, a real quantum computing company, or with Quant Network.
Try it: the QNT Quantum Lab
Run a quantum coin flip, build an entangled pair and design your own 3 qubit circuit in the free QNT Quantum Lab. It is a simulator that runs in your browser, not a real quantum computer, and it needs no account or token.
Quantum education hub
Start with these guides, from first steps to the details. There are 375 guides in total on the Learn page.
Start here
- Quantum Computing for Beginners: A 10 Minute Guide
Quantum computing for beginners: qubits, superposition, entanglement, interference and measurement in plain English, what quantum computers are good for, and where the technology stands. - How Does a Quantum Computer Work? A Step by Step Explanation
How a quantum computer works step by step: prepare qubits, apply gates, entangle, measure, repeat, and correct errors. With a worked example and why simulating one classically gets hard fast. - What Is Quantum Computing? A Plain English Guide
Quantum computers use qubits instead of bits. Learn what quantum computing is, what it is good at, and why the crypto world pays attention. - What Is a Qubit? Superposition and Measurement Explained
A qubit is the basic unit of a quantum computer. Learn how qubits work, how they are built, and why they are fragile. - Superposition Explained in Plain English
Superposition lets a qubit hold a blend of 0 and 1. Here is what it really means, what it does not mean, and why it matters. - Quantum Entanglement Explained Simply
Entanglement links qubits so they share a joint state. Learn what it is, what it is not, and why quantum computers use it. - Types of Quantum Computers: Superconducting, Ion, Photonic and More
A guide to the main ways quantum computers are built, with the strengths and trade-offs of each approach. - Quantum Computing Myths and Misconceptions
Common quantum computing myths, from 'it tries every answer at once' to 'Bitcoin breaks tomorrow'. Learn what is true, what is hype and what is still uncertain.
Algorithms and hardware
- Grover's Algorithm Explained Step by Step
How does Grover's algorithm work? Learn amplitude amplification, why the speedup is only quadratic, and what it really means for keys and hashes. - How a Quantum Program Runs: Circuit to Result
What happens when you run a quantum program? Follow a circuit through compilation, native gates, hardware execution, shots, noise and the counts you get back. - Google Quantum AI: Willow, Error Correction and Quantum Echoes
What Google's Willow chip and the Quantum Echoes result showed, why below-threshold error correction matters, and what is still unproven. - IBM's Quantum Roadmap: From Nighthawk to Starling in 2029
IBM's published plan for fault tolerant quantum computing: processors per year, the Starling system, and what to watch in 2026 and 2027.
Quantum and crypto security
- What Is a Quantum-Resistant Cryptocurrency? Plain English Guide
A quantum-resistant cryptocurrency uses signatures that a quantum computer is not known to break. What that means, the NIST standards, the trade offs, and why the label alone proves little. - Blockchain vs Quantum Computing: What Is Actually at Risk
Which parts of a blockchain a quantum computer could threaten: signatures, mining and exposed public keys, how likely each is, and what a migration involves. With primary sources. - Elliptic Curve Cryptography Explained for Crypto Users
Elliptic curve cryptography secures Bitcoin and Solana wallets. Learn how it works in plain English and why a large quantum computer could threaten it. - Harvest Now, Decrypt Later: The Quantum Threat Explained
Harvest now, decrypt later means collecting encrypted data today to unlock it with a future quantum computer. What it is and who should care. - Q-Day Explained: What It Means, Why Nobody Knows the Date, and the Early Warning Signs
Q-Day is the day a quantum computer can break today's public key cryptography. Here is what it really means, why dates are ranges, and what signs to watch. - Government Post-Quantum Deadlines: NIST, NSA CNSA 2.0 and Federal Migration
The dates governments have set to move off RSA and elliptic curves: NIST 2030 and 2035, NSA CNSA 2.0 milestones, and the January 1, 2027 acquisition rule. - Ethereum and Solana Post-Quantum Plans: What Is Real in 2026
Ethereum's four-part quantum roadmap and Solana's Winternitz Vault and testnet work, with dates and honest caveats.
Keep learning
- How to Try a Quantum Computer Online
You can run real quantum circuits from your browser. Here is a beginner guide to cloud quantum access, simulators, free tiers and what to try first. - Free Quantum Courses and Textbooks: A Verified Reading List
Real, checked places to learn quantum computing for free in 2026: IBM Quantum Learning, PennyLane, Watrous, O'Donnell's lecture notes and the classic Nielsen and Chuang text. - How to Follow Quantum News Without Getting Fooled by Hype
The best primary sources, trade outlets and habits for tracking quantum computing news, plus red flags for exaggerated claims.
Glossary of quantum and crypto terms | Quantum calendar | Search all guides
Sources
- IBM: What is quantum computing? and IBM quantum roadmap
- NIST: Post-Quantum Cryptography project
- Shor (1994/1997), arXiv:quant-ph/9508027
- Preskill (2018), Quantum Computing in the NISQ era and beyond, arXiv:1801.00862
- Google Quantum AI (2024), Quantum error correction below the surface code threshold, arXiv:2408.13687
- Gidney (2025), How to factor 2048 bit RSA integers with less than a million noisy qubits, arXiv:2505.15917
This page is educational. It is not investment advice.
Frequently asked questions
What is a qubit?
A qubit is the basic unit of quantum information. Unlike a bit, which is 0 or 1, a qubit can be in a combination of both until it is measured. See what is a qubit.
What can quantum computers do today?
Today's machines are small and noisy. They are used for research, for demonstrations and to test algorithms. They cannot yet do large useful calculations, and large scale error corrected machines are still being built.
Will quantum computers break Bitcoin and Solana?
Not with any machine that exists today. A large, error corrected quantum computer could break the elliptic curve signatures these chains use, which is why post-quantum upgrades are being studied. See the full answer.
Is QNT a quantum computing cryptocurrency?
No. QNT only borrows the quantum computing theme. It is an ordinary token on Solana, not a quantum computer, not a quantum resistant blockchain and not a project that builds quantum technology. Solana uses Ed25519 signatures, the same kind of elliptic curve cryptography that a future large quantum computer could threaten, as NIST explains in its post-quantum cryptography project. See will quantum computers break Bitcoin and Solana.
Keep reading
- What Is QNT?
QUANTUM (QNT) is a quantum themed community memecoin on Solana. What it is, what it is not, who is behind it, its purpose and risks, and its links to no company. - QNT Frequently Asked Questions
Short, sourced answers about QNT on Solana: what it is, the official contract address, how to buy, whether it is affiliated with Quantinuum or Quant Network, its purpose and its risks. - QNT Token Information
The official QNT contract address on Solana, token standard, supply, burnt supply, revoked authorities, trading pool and official links, with how to verify each fact on Solscan.