Enter the quasiparticle trapping transistor

21 September 2000


A new device that can operate in close proximity to highly sensitive superconducting sensors could open up new detector possibilities. For years a superconducting three-terminal device with transistor-like properties has been the missing link in the development and utilization of superconducting electronics.

A superconducting computer was the major goal of Josephson junction technology in the 1980s. Since then the field of superconducting electronics has broadened tremendously. There are extensive developments with superconducting quantum interference devices, logic circuits and passive microwave components with many applications to telecommunications.

Now a Naples-Oxford collaboration has fabricated a superconducting device that behaves in a similar way to a transistor – the “quasiparticle trapping transistor”, or quatratran – and it demonstrates large current- and power amplifying capability at liquid-helium temperature (Pepe et al. 2000).

Quatratrans can operate in close proximity to the sensitive superconducting sensor arrays that are increasingly being used in astronomy, X-ray microanalysis and time-of-flight mass spectrometry. They can also be fabricated to act as radiation detectors with internal amplification. Conventional semiconductor transistor-like devices do not work well at low temperatures and dissipate too much power.

The idea of quasiparticle trapping (Booth 1987) grew out of attempts to develop a solar neutrino detector based on superconducting indium. Extensions of the idea are being applied to cryogenic detectors, which are being used to search for possible weakly interacting massive particles that may constitute the dark matter of the universe (Irwin et al. 1995), and to superconducting tunnel junction detectors being used in arrays of single-photon counting spectrometers in astronomy (Peacock 2000; Peacock et al. 1996).

Another idea by a Harvard-Oxford collaboration led to the concept of a superconducting transistor (Booth et al. 1999; 2000). A collaboration between Oxford and the Naples group, which has a long tradition in superconductive device fabrication and studies of Josephson effects and non-equilibrium superconductivity (Barone and Paterno 1982), has produced devices that have very interesting properties.

Possible applications of the device are in the area of the preamplification and read-out of multipixel arrays of superconducting sensors and detectors.

Further reading

A Barone and G Paterno 1982 Physics and Applications of the Josephson Effect (Wiley-Interscience).
N E Booth 1987 Quasiparticle trapping and the quasiparticle multiplier Appl. Phys. Lett. 50 293.
N E Booth et al. 1999 A superconducting transistor based on quasiparticle trapping Supercond. Sci. Technol. 12 538.
N E Booth et al. 2000 The Quatratran Nucl. Instrum. Methods A 444 33.
K D Irwin et al. 1995 A quasiparticle-trap-assisted transition-edge sensor for phonon-mediated particle detection Rev. Sci. Instrum. 66 5322.
A Peacock 2000 Physics in space CERN Courier 40(2) 22.
A Peacock et al. 1996 Single optical photon detection with a superconducting tunnel junction Nature 381 135.
G P Pepe et al. July 2000 A superconducting device with transistor-like properties including large current amplification Appl. Phys. Lett.

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