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Thailand Electrical Engineering Journal (TEEJ)

The simulation of single cooper pair trasistor for megnetic flux detector

Jutarat Tanarom

Published Nov 13, 2024• 0 citations
OpenAlex

Abstract

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.

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The single Cooper pair josephson transistor is a device that exhibits at the same time charge quantization and phase coherence. Coherent quantum phase slip phenomenon is “dual” the Josephson phase coherence, while the charge quantization is dual to the flux quantization. We present the experimental demonstration and the theoretical description of a new superconducting device–single flux transistor, which is dual to the single Cooper pair transistor. Our transport measurements show the periodic modulation of the critical voltage by the external magnetic field. The obtained current-voltage characteristics show the hysteretic behavior, which we attribute to the intrinsic self-heating of charge carriers.

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

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A. O. Niskanen, Jani M. Kivioja, Heikki Seppä +1 more

We have experimentally demonstrated pumping of Cooper pairs in a single-island mesoscopic structure. The island was connected to leads through SQUID (superconducting quantum interference device) loops. Synchronized flux and voltage signals were applied whereby the Josephson energies of the SQUIDs and the gate charge were tuned adiabatically. From the current-voltage characteristics one can see that the pumped current increases in $1e$ steps which is due to quasiparticle poisoning on the measurement time scale, but we argue that the transport of charge is due to Cooper pairs.

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Carbon nanotube based magnetic flux detector for molecular spintronics

Jean-Pierre Cleuziou, Wolfgang Wernsdorfer, Vincent Bouchiat +2 more

Abstract This work describes the study of a superconducting quantum interference device (SQUID) with single‐walled carbon nanotube (CNT) Josephson junctions. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of the switching current with magnetic flux is achieved when both QD junctions are in the ‘on’ or ‘off’ state. In particular, the SQUID design establishes that these CNT Josephson junctions can be used as gate‐controlled π junctions. Besides, the CNT‐SQUIDs are sensitive local magnetometers, which are very promising for the study of magnetization reversal of an individual magnetic particle or molecule placed on one of the two CNT Josephson junctions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

physica status solidi (b)•Oct 1, 2007•4 citations
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.
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.
The single Cooper pair josephson transistor is a device that exhibits at the same time charge quantization and phase coherence. Coherent quantum phase slip phenomenon is “dual” the Josephson phase coherence, while the charge quantization is dual to the flux quantization. We present the experimental demonstration and the theoretical description of a new superconducting device–single flux transistor, which is dual to the single Cooper pair transistor. Our transport measurements show the periodic modulation of the critical voltage by the external magnetic field. The obtained current-voltage characteristics show the hysteretic behavior, which we attribute to the intrinsic self-heating of charge carriers.
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.
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 2e2e2e-periodic switching current versus gate charge. As the magnetic field is increased the switching current stays 2e2e2e-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 have experimentally demonstrated pumping of Cooper pairs in a single-island mesoscopic structure. The island was connected to leads through SQUID (superconducting quantum interference device) loops. Synchronized flux and voltage signals were applied whereby the Josephson energies of the SQUIDs and the gate charge were tuned adiabatically. From the current-voltage characteristics one can see that the pumped current increases in 1e1e1e steps which is due to quasiparticle poisoning on the measurement time scale, but we argue that the transport of charge is due to Cooper pairs.
Abstract This work describes the study of a superconducting quantum interference device (SQUID) with single‐walled carbon nanotube (CNT) Josephson junctions. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of the switching current with magnetic flux is achieved when both QD junctions are in the ‘on’ or ‘off’ state. In particular, the SQUID design establishes that these CNT Josephson junctions can be used as gate‐controlled π junctions. Besides, the CNT‐SQUIDs are sensitive local magnetometers, which are very promising for the study of magnetization reversal of an individual magnetic particle or molecule placed on one of the two CNT Josephson junctions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)