Josephson constant

Josephson constant

[′jō·sef·sən ‚kän·stənt]
(physics)
The quantity KJ = 2 e/h, which appears in the equations for the alternating-current Josephson effect, where e is the magnitude of the charge of the electron and h is Planck's constant.
The conventional value of this quantity adopted by international agreement on January 1, 1990, to establish a standard for the volt, KJ-90= 493,597.9 gigahertz per volt.
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The QVNS generates an accurate synthetic pseudorandom noise signal with mean-square voltage <[V.sup.2.sub.Q]> = [[absolute value of ([v.sub.JJ])].sup.2]/[K.sup.2.sub.J], where JJ indicates the Josephson junction, [absolute value of ([v.sub.JJ])] is a noise power spectral density that is calculable from QVNS implementation details, and [K.sub.J] is the conventional value for the Josephson constant. When the resistance of the thermal noise source is expressed in terms of the conventional value of the von Klitzing constant [R.sub.K-90], the measured ratio <[V.sup.2.sub.R]>/<[V.sup.2.sub.JJ]> will be proportional to k/h, the ratio of the Boltzmann constant to the Planck constant.
Therefore, at frequencies much less than the inverse width of the quantized pulse, the waveform is exactly proportional to the Josephson constant [K.sub.J] and the pulse generator clock.
The last three constants are determined by other means, but are included since they are used in some of the other determinations Constant Symbol Planck constant h Josephson constant (SI) [K.sub.J] = 2e/h Electron mass [m.sub.e] Proton mass [m.sub.p] Avogadro constant [N.sub.A] Elementary charge e Josephson constant [K.sub.J-90] von Klitzing constant [K.sub.K-90] l/(fine-structure constant) l/[alpha] Rydberg constant [R.sub.[infinity]] Electron's atomic mass [m.sub.e]/[m.sub.u] Unc.
Key words: DLC coating; hysteresis; Josephson constant; kilogram artifact; Planck constant; watt balance.
These include the Josephson constant, the charge and mass of the electron, and the Avogadro constant [2].
The widespread use of Josephson junction arrays in national standards laboratories, and better SI determinations of 2e/h, led the CCE to recommend (57) a new exact conventional value for the Josephson constant:
The relationship can be expressed by the equation V = nf/[K.sub.J], where V is the quantized voltage, n is an integer, f is the microwave frequency, and [K.sub.J] = 2e/h is the Josephson constant determined by the Plank constant h and the elementary charge e.
When the CCE recommended international acceptance of the value of the Josephson constant [K.sub.J-90] = 483 597.9 GHz/V beginning Jan.
The Josephson constant [K.sub.J] is based both on its direct measurement by voltage balances and by combining [R.sub.K] with a value of the Planck constant, the latter obtained by realizing the watt in a special way.
where n and i are integers, e is the elementary charge, h is the Planck constant, f is the frequency of the microwave radiation applied to a Josephson device, [K.sub.J] is the Josephson constant, and [R.sub.K] is the von Klitzing constant.