Catalog — Metric definitions
What hardware metrics actually mean
Every metric page defines the figure, explains how it is measured, and — the part most spec sheets omit — states when two values of it are not comparable. That caveat is the difference between reading a spec sheet and being misled by one.
Definitions5 metrics
dimensionlessTwo-qubit gate fidelityTwo-qubit gate fidelity is the chance that a gate acting on two qubits does exactly what it should. A fidelity of 99.5% means an error rate of about 0.5% per gate. It is µs / ms / sCoherence times (T1 and T2)T1 and T2 are coherence times: how long a qubit keeps its information before noise wears it away. T1 is how long a qubit holds its energy (a stored 1). T2 is how long it dimensionlessReadout fidelityReadout fidelity is the chance that measuring a qubit reports the state it was really in. A readout fidelity of 99% means about 1 wrong answer per 100 qubit reads. Every layersCircuit depthCircuit depth is the number of steps a quantum circuit needs when every gate that can run at the same time does. It is the length of the longest chain of gates that must qubitsQubit countQubit count is how many qubits a processor has. On its own it ranks nothing. How much a machine can really do depends on how good its gates are, how its qubits are connec