Quantum Computing
Last Updated: July 29, 2026 | By Mihail Sebastian | AI Dictionary
Computing that uses qubits, which hold multiple states at once, to solve certain problems like molecular simulation far faster than classical machines.
What is Quantum Computing?
Quantum computing performs calculations with qubits, units of information that hold multiple states at once, where a classical bit is either 0 or 1. That property lets a quantum computer work through certain problems, such as simulating molecules, that would take classical machines an impractical amount of time.
The key word is “certain”: quantum computers are not faster general-purpose machines. They promise speedups only for specific problem classes, and today’s hardware is still small and error-prone.
How Quantum Computing Works
- Superposition: A qubit represents 0 and 1 at the same time, so a register of qubits encodes many candidate answers in parallel.
- Entanglement: Entangled qubits share a linked state; measuring one constrains the other, which lets an algorithm coordinate information across the whole register.
- Interference: Quantum algorithms are designed so that wrong answers cancel out and right answers reinforce before the result is measured.
Applications of Quantum Computing
- Cryptography: Shor’s algorithm would let a large quantum computer factor the numbers behind widely used public-key encryption, which is why post-quantum encryption standards are being rolled out now.
- Chemistry and materials: Molecules are quantum systems, so qubits represent them directly; classical computers hit a wall because the number of possible states grows exponentially with molecule size.
- Optimization: Routing, scheduling, and portfolio problems are candidates for quantum speedups, though practical advantage over classical methods remains unproven.
Example of Quantum Computing
Simulating a battery electrolyte molecule shows the gap. To predict how the molecule behaves, a classical computer must track every possible configuration of its electrons, and that number doubles with each electron added; past a few dozen, no supercomputer holds the state.
A quantum computer sidesteps the explosion because its qubits are quantum objects themselves: the molecule’s state maps onto the hardware’s state. Chemistry simulations like this are widely expected to be among the first commercially useful quantum workloads once machines have enough reliable qubits.
For AI specifically, quantum machine learning is an active research field, but no quantum computer today trains or runs practical models better than ordinary hardware.
Related AI terms: Machine Learning · Optimization · Security · Edge Computing
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Mihail Sebastian — Writes about AI governance, regulation, and the technology behind them. Placeholder bio — replace with a real credential line. About