What is the magnetic flux quantum?

The magnetic flux quantum is Φ_0 = 2.067833848e-15 Wb, exact by SI definition. It equals h/(2e).

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Key facts

Value2.067833848e-15 Wb
SymbolΦ_0
RelationΦ_0 = h/(2e)
ExactnessExact by SI definition (uncertainty 0)
SourceCODATA 2018

Frequently asked questions

What is the value of the magnetic flux quantum?

Φ_0 = 2.067833848e-15 Wb, the smallest unit of magnetic flux through a superconducting loop.

Where is the flux quantum used?

In superconductivity and SQUID magnetometers, where flux through a loop is quantized in units of Φ_0.

How is Φ_0 defined?

Φ_0 = h/(2e), where the factor of 2 reflects Cooper pairs in superconductors.

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