Parallel-channel nanocryotrons in magnetic fields

Superconductors can carry large electrical currents without any resistance. One situation where they don’t carry currents without resistance is when there is too much current. By designing microscopic electronic components made from very thin superconductors, researchers can use this effect to create a switch, like a transistor.

A scanning electron microscope image of the superconducting nanowire switch. Large electric output currents in the green channel can be switched on and off by small input currents in the red gate terminal. Blue is the superconducting ground plane. Source: Argonne National Laboratory

Nanowire superconducting switching devices (called nanocryotrons, or nTrons for short) show promise for future superconducting electronics or particle detectors. For example, they may be ideal for future electron-ion colliders. Now, a team of scientists has showed 1 that small changes in the geometry of a switch can increase the currents at which these switches can reliably operate. The research also showed these switches perform in magnetic fields, a key step for many applications.

The nTron technology has seen significant research interest, as it allows the development of basic logic elements that can be used in complex superconducting electronics, such as readout or data-processing circuits attached to superconducting detectors of light and charged particles such as electrons. This operation is achieved by injecting small gate currents through a small gate terminal, which launches an electro-thermal cascade in a connected large current-carrying channel that temporarily destroys superconductivity in the channel. Because many experiments where these devices would operate, including particle collider experiments and quantum communication networks, have magnetic fields, researchers must show that these devices can operate and perform well in these fields.

The results of this research show that changes to the geometry of the thin film device can lead to increased performance in multiple aspects, such as electric current gain and reset times. Furthermore, a first-of-its-kind test in a magnetic field showed that these devices can already operate in moderately strong magnetic fields, albeit with degrading performance.

Based on these findings, researchers can develop future devices that harness geometric modifications to endure much stronger magnetic fields. They can also begin to develop integrated superconducting nanowire sensors and electronic systems. These innovations will serve as the foundation for a wide spectrum of experiments, spanning a range of applications from particle tracking systems within colliders to quantum communication network repeaters.


  1. Timothy Draher, Tomas Polakovic, Yi Li, John Pearson, Alan Dibos, Zein-Eddine Meziani, Zhili Xiao, Valentine Novosad (2023) Design and performance of parallel-channel nanocryotrons in magnetic fields. Appl. Phys. Lett. doi:10.1063/5.0180709

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