Quantum of circulation
Atomic & nuclearMeasured
= 3.636 947 5467(11) × 10−4 m2 s−1
- Value
- 3.636 947 5467 × 10−4 m2 s−1
- Standard uncertainty
- 1.1 × 10−13 m2 s−1
- Relative uncertainty
- 3.0 × 10−10 (302 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# quantum of circulation, CODATA 2022 (NIST)
quantum_of_circulation = 3.6369475467e-4 # m^2 s^-1, standard uncertainty 1.1e-13
# SciPy: scipy.constants.physical_constants['quantum of circulation']What it is
h/(2mₑ): the unit in which the circulation of a superconducting current of electron pairs is quantised. Superfluid helium-4 follows the same rule with the helium atom's mass.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 s−1) | 3.636 947 5467 |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 3.636 947 5467(11) × 10−4 | 3.0 × 10−10 | −4.5 σ of 2018 |
| 2018 | 3.636 947 5516(11) × 10−4 | 3.0 × 10−10 | +1.8 σ of 2014 |
| 2014 | 3.636 947 5486(17) × 10−4 | 4.7 × 10−10 | −1.4 σ of 2010 |
| 2010 | 3.636 947 5520(24) × 10−4 | 6.6 × 10−10 | +6.4 σ of 2006 |
| 2006 | 3.636 947 5199(50) × 10−4 | 1.4 × 10−9 | −1.3 σ of 2002 |
| 2002 | 3.636 947 550(24) × 10−4 | 6.6 × 10−9 | +1.3 σ of 1998 |
| 1998 | 3.636 947 516(27) × 10−4 | 7.4 × 10−9 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).