The DiVincenzo Criteria
The DiVincenzo criteria are five requirements a physical system must meet to serve as a quantum computer, plus two for communication.
A checklist for hardware
In 2000 David DiVincenzo listed the conditions any physical platform must satisfy to be a viable quantum computer. The five criteria remain the standard framework for comparing technologies like superconducting circuits, trapped ions, and spin qubits.
The five criteria
- Scalable qubits: a well-characterised two-level system that can be replicated in large numbers
- Initialisation: the ability to reliably prepare a known starting state such as |000...0>
- Long coherence: coherence times much longer than gate operation times
- Universal gates: a universal set of controllable gates
- Measurement: the ability to read out individual qubits reliably
Tension between criteria
The criteria pull against each other. Strong coupling for fast gates and readout also couples qubits to noise, shortening coherence. Good isolation preserves coherence but makes control harder. Every platform is an engineering compromise across these five, and no technology yet dominates on all of them.
The two networkability criteria
DiVincenzo added two more for quantum communication: the ability to convert stationary qubits into flying qubits (usually photons), and the ability to transmit those flying qubits faithfully between locations. These matter for distributed quantum computing and quantum networks rather than a single processor.
Using the framework
When assessing any quantum hardware claim, the criteria are the questions to ask: How many qubits, and does the design scale? What are the fidelities and coherence times relative to gate speed? Is the gate set universal, and how good is readout? A platform strong on qubit count but weak on fidelity may compute less than a smaller, cleaner one.