Voltage oscillation mechanism for a superconducting quantum interferometer

V. A. Khlus, I. O. Kulik

A study is made of the effects of quantum interference in weakly coupled superconducting systems in an external magnetic field, allowance being made for fluctuations. The circulating supercurrent is found as a function of the applied magnetic field for a weakly coupled ring when the coupling is comparable in magnitude with the thermal energy. The current--voltage characteristic for a superconducting quantum interferometer is found and it is shown that the amplitude of the steps formed in the current--voltage characteristic under the influence of external irradiation is an oscillating function of the flux of the applied magnetic field with a period equal to the flux quantum. (AIP)

E. Altshuler, Alexandre Satrapinski

Gely F. Zharkov, Andrei D. Zaikin

Junliang Jiang, Jiazheng Pan, Yongchao Li +7 more

Mechanical oscillators can be implemented to store and transfer information or to build hybrid systems. In order to couple a mechanical oscillator to a superconducting qubit, we fabricate a superconducting capacitor, in which diluted photoresist or electron beam photoresist is used as sacrificial layers. The upper plate of the capacitor, a suspended membrane, acts as a mechanical oscillator. We obtain its mechanical resonant frequency and response to the input microwave. Such mechanical oscillators can be used as the capacitor of a superconducting qubit to form a coupled system. In order to control the resonant frequency of the mechanical oscillator and the microwave resonator, we introduce a dc voltage bias between the upper and lower plates of the capacitor. We analyze the electromechanical coupling such as pull-in effect and experimentally demonstrate the dependence of the resonant frequency on the applied dc voltage. These results will contribute to the design and fabrication of hybrid systems comprising voltage-controlled mechanical oscillators and other systems.

J. M. V. Verschueren, A. A. Uiterwaal, Rob W. van der Heijden +1 more

A current controlled voltage across a resistive section in a double Josephson junction interferometer (dc resistive superconducting quantum interference device) maintains a difference voltage between the junctions to generate a narrowband oscillatory signal at the beat frequency νq of the individual junction frequencies. This internal oscillation was used to directly down-convert a signal at 246 GHz to a very low (<1 MHz) intermediate frequency.

K. B. Lobanov, С. И. Бондаренко, A. G. Davydova +1 more