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Quantum Hardware Basics

IntermediateQuantum hardware7 min read

By QuantumO Editorial · Scientific reviewer: not yet assigned · Published · Updated

In short

Quantum hardware turns physical systems into controllable qubits. Superconducting circuits, trapped ions, neutral atoms, photons, and spins each offer different coherence times, gate speeds, and connectivity. All require extreme isolation from noise, and no platform has yet proven decisively superior.

Common platforms

Superconducting qubits are lithographically fabricated circuits operated near absolute zero, with fast gates and shorter coherence times. Trapped ions use individual atoms held by electromagnetic fields, offering long coherence and high fidelity but slower operations.

Neutral atoms allow flexible, reconfigurable arrays. Photonic approaches move quantum information easily and are natural for networking, but deterministic two-qubit gates are difficult.

What the specifications mean

Coherence time indicates how long a qubit holds its state. Gate fidelity measures how accurately operations are applied. Connectivity describes which qubits can interact directly. Read these together — a single headline number rarely tells you what a machine can do.

Common misconceptions

Claim: All quantum computers must be near absolute zero.
More accurately: Superconducting machines do require dilution refrigerators, but photonic and some atomic approaches operate differently.

Important terminology

Qubit
A qubit is the basic unit of quantum information: a two-level quantum system that can hold a combination of the outcomes 0 and 1.
Coherence
Coherence is the property that lets a quantum system maintain well-defined relationships between its amplitudes, making interference possible.
Decoherence
Decoherence is the loss of quantum behaviour that happens when a system becomes correlated with its environment.

Frequently asked questions

What are qubits physically made of?
Superconducting circuits, trapped ions, neutral atoms, photons, and electron or nuclear spins are all used as qubits.

Sources and further reading

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