(a) Circuit diagram of a current biased JJ in the RCSJ model. Damping of the JJ due to the environment and due to intrinsic effects is described by an admittance, Y. (b) Energy levels in the potential of the current biased JJ. Microwave radiation induces a transition from the ground state to the first excited state having a larger escape rate than the ground state.
(Color online) (a) Circuit diagram of an LC shunted JJ. (b) Two-dimensional potential, U (for details, see Ref. 7), of an LC shunted JJ for a bias current of , , and . Here, denotes the Josephson coupling energy.
(Color online) Plasma frequency, , for a single junction, upper normal mode, , of the LCJJ system, and lower normal mode, , of the LCJJ system. The insets show a magnification of the lower mode close to . (a) For and . (b) For and .
(Color online) (a) Photo of an LCJJ8-type sample. The capacitor is situated on the left while the JJ can be found on the right. The two meander lines connecting these elements act as inductors. The bottom electrode is shown on the upper part of the picture and has changed color due to the anodic oxidation. (b) SEM image of the Josephson junction. The SiO insulation layer can be seen as the dark circle.
(Color online) IV curve of a single junction having a diameter of d = 3 μm without the shell circuit. The high I c R N and V gap values show that a very high quality was reached. The inset shows a magnification of the subgap branch, as measured with a voltage bias configuration.
(Color online) Measurements of shell circuits without the JJ. We found clear resonances at the expected frequencies with high loaded quality factors (see Table I).
(Color online) Spectroscopy data (gray points) of sample LCJJ2 without an applied magnetic field. An excellent agreement between the experiment on one side and design values and theory on the other side is observed.
(Color online) Spectroscopy data (gray points) of sample LCJJ2 with an applied magnetic field, suppressing the critical current to I c = 3.82 μA. The agreement between theory and experiment is excellent.
Measurement results for four investigated shell circuits without junctions. The experimentally determined resonance frequencies are within 3% of the ones calculated from the L s and C s design values. Additionally, high loaded quality factors Q L were obtained.
Design parameters of an LC shunted Josephson junction.
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