This article presents a study on the characteristics of single Cooper-pair transistors when integrated into a Superconducting Quantum Interface Device (SQUID) circuit. SQUID is a highly sensitive magnetometer that uses phase balance checks through single Cooper-pair transistors when Josephson currents flow. The study explores the tuning of the supercurrent of the single Cooper-pair transistors in a circuit with a loop coupled to gate voltage. Understanding the behavior of single Cooper-pair transistors in this loop structure is crucial for integrating them with other superconducting electronic circuits. The research includes simulations of the single Cooper-pair transistor in one branch of a SQUID loop circuit. The simulation results indicate that single Cooper-pair transistors can be used as superconducting current switches.This article presents a study on the characteristics of single Cooper-pair transistors when integrated into a Superconducting Quantum Interface Device (SQUID) circuit. SQUID is a highly sensitive magnetometer that uses phase balance checks through single Cooper-pair transistors when Josephson currents flow. The study explores the tuning of the supercurrent of the single Cooper-pair transistors in a circuit with a loop coupled to gate voltage. Understanding the behavior of single Cooper-pair transistors in this loop structure is crucial for integrating them with other superconducting electronic circuits. The research includes simulations of the single Cooper-pair transistor in one branch of a SQUID loop circuit. The simulation results indicate that single Cooper-pair transistors can be used as superconducting current switches.

Thailand Electrical Engineering Journal (TEEJ)Nov 13, 20240 citations

Switching current of a Cooper pair transistor with tunable Josephson junctions

Peter Ågren, J. Walter, David B. Haviland

We investigate the switching current of a Cooper pair transistor with tunable Josephson energy. The junctions are fabricated in a superconducting quantum interference device (SQUID) geometry which allows for an in situ tunable effective Josephson energy by application of a magnetic field. We find a $2e$ -periodic switching current versus gate charge. As the magnetic field is increased the switching current stays $2e$ -periodic but the magnitude is suppressed. At a magnetic field of half a flux quantum through the SQUID's the switching current is minimum. We can theoretically model the experimental data by assuming a switching current which is proportional to the ideal critical current squarred. We show that such a dependence is expected in the limit where the effect of thermal fluctuations on the system is strong.We investigate the switching current of a Cooper pair transistor with tunable Josephson energy. The junctions are fabricated in a superconducting quantum interference device (SQUID) geometry which allows for an in situ tunable effective Josephson energy by application of a magnetic field. We find a $2e$-periodic switching current versus gate charge. As the magnetic field is increased the switching current stays $2e$-periodic but the magnitude is suppressed. At a magnetic field of half a flux quantum through the SQUID's the switching current is minimum. We can theoretically model the experimental data by assuming a switching current which is proportional to the ideal critical current squarred. We show that such a dependence is expected in the limit where the effect of thermal fluctuations on the system is strong.

Physical review. B, Condensed matterJun 28, 20026 citations

A Quantum Transistor with Superconducting Qubits

Niels Jakob Søe Loft, Lasse Bjørn Kristensen, Christian Kraglund Andersen +1 more

Bulletin of the American Physical SocietyMar 6, 20180 citations

2e

-periodic switching current versus gate charge. As the magnetic field is increased the switching current stays

2e

-periodic but the magnitude is suppressed. At a magnetic field of half a flux quantum through the SQUID's the switching current is minimum. We can theoretically model the experimental data by assuming a switching current which is proportional to the ideal critical current squarred. We show that such a dependence is expected in the limit where the effect of thermal fluctuations on the system is strong.