Frequency Pulling in Josephson Junctions

B. T. Ulrich

D. E. McCumber

Thilo Bauch, Edoardo Trabaldo, Floriana Lombardi

D. E. McCumber

Contrary to recent suggestions, cavity detuning per se does not modify the Josephson relation ${\ensuremath{\omega}}_{J}(V)=2e\frac{V}{\ensuremath{\hbar}}$, although it can produce measurable differences between the electrostatic and electrochemical potentials in a Josephson junction.

Marlan O. Scully, Patrick A. Lee

Using techniques developed in the quantum theory of the laser, we show that the frequency of the radiation emitted from a superconducting tunnel junction may be pulled slightly from $\frac{2eV}{\ensuremath{\hbar}}$ and present a physical discussion and numerical estimate of the effect.

Q. Geng, Eiichi Goto

A novel Josephson junction magnetometry scheme is proposed in which magnetic flux is applied to Josephson junctions with a modulation flux +or-z( Phi /sub 0//2 pi ) cos omega t. Two Josephson junctions are used in a push-pull mode to perform amplification through two mechanisms: negative inductance amplification of DC (low frequency) components and parametric amplification of the second harmonic. The second harmonic component of the Josephson currents, which is directly proportional to the strength of the input flux, is then selected and amplified by a phase-sensitive detector. Computer simulations show that the device behaves very well as a magnetic flux sensor with a DC offset free feature. The device's parameters and noise problems are also discussed. A preliminary analysis indicates that it is likely to have a better sensitivity than superconducting quantum interference devices.>