What it is and the problem it solves
Quantum computing is a computational paradigm that uses quantum states to represent and process information. It solves problems intractable for classical machines—specifically integer factorisation, unstructured search, and quantum simulation—but only in theory or narrow demonstration.
How it works
Quantum computing processes information using qubits, which exist in quantum superposition—unlike classical bits. It exploits superposition, interference, and entanglement. Wave interference amplifies the probability of desired measurement outcomes. Measuring a qubit yields one of two states probabilistically.
What works
Small-scale quantum algorithms work in controlled settings: Shor’s algorithm factors integers; Grover’s algorithm searches unstructured data. Google’s 2019 Sycamore experiment achieved quantum supremacy—a milestone confirming quantum speedup on a contrived task—but not practical utility.
What does not
Quantum computers do not run general-purpose software. They do not replace classical computers. They cannot execute everyday tasks like web browsing or document editing. Error correction remains unsolved. Decoherence limits computation time. Scalability is unproven.
What it changes
It changes how we model physical systems at quantum scale—and threatens public-key cryptography. A large-scale quantum computer could break widely used encryption schemes and aid physicists in performing physical simulations. That threat drives post-quantum cryptography research now.
Is it worth your time
Not yet for applied work. No quantum computer solves real-world problems faster than classical alternatives. Current systems are experimental, noisy, and require cryogenic cooling. They deliver scientific milestones—not production tools.
