Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Japanese Journal of Applied Physics

Scalability of supercurrent modulable with single Cooper-pair transistors connected in parallel

Jutarat Tanarom, Yoshinao Mizugaki, Hiroshi Shimada

Published Jun 9, 2021• 1 citation
Publisher

Abstract

Abstract A single Cooper-pair transistor (SCPT) can work as a fast supercurrent switch. However, a direct combination of an SCPT with other superconducting-electronics circuits is not easy because of the smallness of the switchable supercurrent with it. In this work, scalability of the supercurrent that can be modulated with an SCPT structure is studied using multiple SCPTs connected in parallel having a common gate electrode. It is found that the magnitude of the maximum supercurrent is scaled up almost linearly with the increase in the number of SCPTs, N , and that it is modulated with the gate voltage as in the case for a single SCPT. The modulability, however, decreases with the increase in N , which is demonstrated to be mostly because of the charge-state fluctuations of either islands of the constituent SCPTs caused by the capacitive coupling among them. A practically possible method of improving the modulability is also discussed.

DOI
10.35848/1347-4065/ac099e

Related papers

The single Cooper pair transistor: a macroscopic quantum system

P. Joyez

In a system where two small-area (100 nm x 100 nm) superconducting tunnel junctions are connected in series, the Josephson effect which tends to impose the phase competes with the charging effects in the central electrode (the of the device) which tend to set the charge of the island. By applying a voltage on an electrode capacitively coupled to the island (the electrode) one can arbitrate this competition in favour of either effect. This is can be seen in particular on the supercurrent which can flow through the junctions : it is modulated periodically by the gate voltage (hence the name of given to the system). This modulation shows sharp peaks when two charge states of the island are degenerate with respect to the electrostatic energy. The system is then in a state which has no classical description : it is in a coherent superposition of states. In this thesis we demonstrate experimentally the behaviour of this transistor and we analyse the theoretical and practical problems which can prevent the observation of the coherent superposition of states through the modulation of the supercurrent. In particular we show that the parity of the electron number in the island must be rigorously controlled and that the impedance connected to the circuit plays a crucial role in setting the magnitude of the measured supercurrent.

•Mar 6, 1995•6 citations

Very High Frequency Spectroscopy and Tuning of a Single-Cooper-Pair Transistor with an On-Chip Generator

P.-M. Billangeon, F. Pierre, Hélène Bouchiat +1 more

A single-Cooper-pair transistor (SCPT) is coupled capacitively to a voltage biased Josephson junction, used as a high-frequency generator. Thanks to the high energy of photons generated by the Josephson junction, transitions between energy levels, not limited to the first two levels, were induced and the effect of this irradiation on the dc Josephson current of the SCPT was measured. The phase and gate bias dependence of energy levels of the SCPT at high energy is probed. Because the energies of photons can be higher than the superconducting gap we can induce not only transfer of Cooper pairs but also transfer of quasiparticles through the island of the SCPT, thus controlling the poisoning of the SCPT. This can both decrease and increase the average Josephson energy of the SCPT: its supercurrent is then controlled by high-frequency irradiation.

arXiv:cond-mat/0607639•Physical Review Letters•Mar 20, 2007•21 citations

The simulation of single cooper pair trasistor for megnetic flux detector

Jutarat Tanarom

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, 2024•0 citations

Le transistor a une paire de cooper : un systeme quantique macroscopique

P. Joyez

In a system where two small-area (100 nm x 100 nm) superconducting tunnel junctions are connected in series, the Josephson effect which tends to impose the phase competes with the charging effects in the central electrode (the "island" of the device) which tend to set the charge of the island. By applying a voltage on an electrode capacitively coupled to the island (the "gate" electrode) one can arbitrate this competition in favour of either effect. This is can be seen in particular on the supercurrent which can flow through the junctions : it is modulated periodically by the gate voltage (hence the name of "transistor" given to the system). This modulation shows sharp peaks when two charge states of the island are degenerate with respect to the electrostatic energy. The system is then in a state which has no classical description : it is in a coherent superposition of states. In this thesis we demonstrate experimentally the behaviour of this transistor and we analyse the theoretical and practical problems which can prevent the observation of the coherent superposition of states through the modulation of the supercurrent. In particular we show that the parity of the electron number in the island must be rigorously controlled and that the impedance connected to the circuit plays a crucial role in setting the magnitude of the measured supercurrent.

•Jan 1, 1995•7 citations

Characteristic of single Cooper pair transistor used as sensitive supercurrent sensor

Jutarat Tanarom, Ploybussara Gomasang

The characteristics of the single Cooper pair transistor, a key component of single-charge electronics that manipulates single or Cooper pair electrons via the Coulomb blockade phenomenon, are discussed in this article. Due to these characteristics, the single Cooper pair transistor plays an important role in metrology such as sensitive electrometry and quantum computing. Electron beam lithography and electron gun evaporation are used to fabricate the single Cooper pair transistor. The measurement is performed at lower temperatures than 100 mK by using a dilution refrigerator. It has been found that only the tunneling of Cooper pairs of electrons is shown by the relationship between the gate voltage and the supercurrent. It indicates that a single Cooper pair transistor can be used as a sensitive sensor when integrated into other devices, exhibiting the tunneling properties of Cooper pairs at 16 GHz.

International Conference on Photonics Solutions (ICPS)•Feb 19, 2025•0 citations

ac Josephson Effect and Resonant Cooper Pair Tunneling Emission of a Single Cooper Pair Transistor

P.-M. Billangeon, F. Pierre, Hélène Bouchiat +1 more

We measure the high-frequency emission of a single Cooper pair transistor (SCPT) in the regime where transport is only due to tunneling of Cooper pairs. This is achieved by coupling on chip the SCPT to a superconductor-insulator-superconductor junction and by measuring the photon assisted tunneling current of quasiparticles across the junction. This technique allows a direct detection of the ac Josephson effect of the SCPT and provides evidence of Landau-Zener transitions for proper gate voltage. The emission in the regime of resonant Cooper pair tunneling is also investigated. It is interpreted in terms of transitions between charge states coupled by the Josephson effect.

arXiv:cond-mat/0609755•Physical Review Letters•May 21, 2007•47 citations
Abstract A single Cooper-pair transistor (SCPT) can work as a fast supercurrent switch. However, a direct combination of an SCPT with other superconducting-electronics circuits is not easy because of the smallness of the switchable supercurrent with it. In this work, scalability of the supercurrent that can be modulated with an SCPT structure is studied using multiple SCPTs connected in parallel having a common gate electrode. It is found that the magnitude of the maximum supercurrent is scaled up almost linearly with the increase in the number of SCPTs, N , and that it is modulated with the gate voltage as in the case for a single SCPT. The modulability, however, decreases with the increase in N , which is demonstrated to be mostly because of the charge-state fluctuations of either islands of the constituent SCPTs caused by the capacitive coupling among them. A practically possible method of improving the modulability is also discussed.
In a system where two small-area (100 nm x 100 nm) superconducting tunnel junctions are connected in series, the Josephson effect which tends to impose the phase competes with the charging effects in the central electrode (the of the device) which tend to set the charge of the island. By applying a voltage on an electrode capacitively coupled to the island (the electrode) one can arbitrate this competition in favour of either effect. This is can be seen in particular on the supercurrent which can flow through the junctions : it is modulated periodically by the gate voltage (hence the name of given to the system). This modulation shows sharp peaks when two charge states of the island are degenerate with respect to the electrostatic energy. The system is then in a state which has no classical description : it is in a coherent superposition of states. In this thesis we demonstrate experimentally the behaviour of this transistor and we analyse the theoretical and practical problems which can prevent the observation of the coherent superposition of states through the modulation of the supercurrent. In particular we show that the parity of the electron number in the island must be rigorously controlled and that the impedance connected to the circuit plays a crucial role in setting the magnitude of the measured supercurrent.
A single-Cooper-pair transistor (SCPT) is coupled capacitively to a voltage biased Josephson junction, used as a high-frequency generator. Thanks to the high energy of photons generated by the Josephson junction, transitions between energy levels, not limited to the first two levels, were induced and the effect of this irradiation on the dc Josephson current of the SCPT was measured. The phase and gate bias dependence of energy levels of the SCPT at high energy is probed. Because the energies of photons can be higher than the superconducting gap we can induce not only transfer of Cooper pairs but also transfer of quasiparticles through the island of the SCPT, thus controlling the poisoning of the SCPT. This can both decrease and increase the average Josephson energy of the SCPT: its supercurrent is then controlled by high-frequency irradiation.
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.
In a system where two small-area (100 nm x 100 nm) superconducting tunnel junctions are connected in series, the Josephson effect which tends to impose the phase competes with the charging effects in the central electrode (the "island" of the device) which tend to set the charge of the island. By applying a voltage on an electrode capacitively coupled to the island (the "gate" electrode) one can arbitrate this competition in favour of either effect. This is can be seen in particular on the supercurrent which can flow through the junctions : it is modulated periodically by the gate voltage (hence the name of "transistor" given to the system). This modulation shows sharp peaks when two charge states of the island are degenerate with respect to the electrostatic energy. The system is then in a state which has no classical description : it is in a coherent superposition of states. In this thesis we demonstrate experimentally the behaviour of this transistor and we analyse the theoretical and practical problems which can prevent the observation of the coherent superposition of states through the modulation of the supercurrent. In particular we show that the parity of the electron number in the island must be rigorously controlled and that the impedance connected to the circuit plays a crucial role in setting the magnitude of the measured supercurrent.
The characteristics of the single Cooper pair transistor, a key component of single-charge electronics that manipulates single or Cooper pair electrons via the Coulomb blockade phenomenon, are discussed in this article. Due to these characteristics, the single Cooper pair transistor plays an important role in metrology such as sensitive electrometry and quantum computing. Electron beam lithography and electron gun evaporation are used to fabricate the single Cooper pair transistor. The measurement is performed at lower temperatures than 100 mK by using a dilution refrigerator. It has been found that only the tunneling of Cooper pairs of electrons is shown by the relationship between the gate voltage and the supercurrent. It indicates that a single Cooper pair transistor can be used as a sensitive sensor when integrated into other devices, exhibiting the tunneling properties of Cooper pairs at 16 GHz.
We measure the high-frequency emission of a single Cooper pair transistor (SCPT) in the regime where transport is only due to tunneling of Cooper pairs. This is achieved by coupling on chip the SCPT to a superconductor-insulator-superconductor junction and by measuring the photon assisted tunneling current of quasiparticles across the junction. This technique allows a direct detection of the ac Josephson effect of the SCPT and provides evidence of Landau-Zener transitions for proper gate voltage. The emission in the regime of resonant Cooper pair tunneling is also investigated. It is interpreted in terms of transitions between charge states coupled by the Josephson effect.