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**Harvard**

Sundqvist, K. och Delsing, P. (2014) *Negative-resistance models for parametrically flux-pumped superconducting quantum interference devices*.

** BibTeX **

@article{

Sundqvist2014,

author={Sundqvist, K.M. and Delsing, Per},

title={Negative-resistance models for parametrically flux-pumped superconducting quantum interference devices},

journal={EPJ Quantum Technology},

issn={2196-0763},

volume={1},

issue={6},

abstract={
A Superconducting QUantum Interference Device (SQUID) modulated by a fast oscillating magnetic flux can be used as a parametric amplifier, providing gain with very little added noise. Here, we develop linearized models to describe the parametrically flux-pumped SQUID in terms of an impedance. An unpumped SQUID acts as an inductance, the Josephson inductance, whereas a flux-pumped SQUID develops an additional, parallel element which we have coined the “pumpistor.” Parametric gain can be understood as a result of a negative resistance of the pumpistor. In the degenerate case, the gain is sensitive to the relative phase between the pump and signal. In the nondegenerate case, gain is independent of this phase.
We develop our models first for degenerate parametric pumping in the three-wave and four-wave cases, where the pump frequency is either twice or equal to the signal frequency, respectively. We then derive expressions for the nondegenerate case where the pump frequency is not a multiple of the signal frequency, for which it becomes necessary to consider idler tones that occur. For the nondegenerate three-wave case, we present an intuitive picture for a parametric amplifier containing a flux-pumped SQUID where current at the signal frequency depends upon the load impedance at an idler frequency. This understanding provides insight and readily testable predictions of circuits containing flux-pumped SQUIDs.},

year={2014},

keywords={parametric amplifiers, SQUIDs, Josephson devices},

}

** RefWorks **

RT Journal Article

SR Electronic

ID 202189

A1 Sundqvist, K.M.

A1 Delsing, Per

T1 Negative-resistance models for parametrically flux-pumped superconducting quantum interference devices

YR 2014

JF EPJ Quantum Technology

SN 2196-0763

VO 1

IS 6

AB
A Superconducting QUantum Interference Device (SQUID) modulated by a fast oscillating magnetic flux can be used as a parametric amplifier, providing gain with very little added noise. Here, we develop linearized models to describe the parametrically flux-pumped SQUID in terms of an impedance. An unpumped SQUID acts as an inductance, the Josephson inductance, whereas a flux-pumped SQUID develops an additional, parallel element which we have coined the “pumpistor.” Parametric gain can be understood as a result of a negative resistance of the pumpistor. In the degenerate case, the gain is sensitive to the relative phase between the pump and signal. In the nondegenerate case, gain is independent of this phase.
We develop our models first for degenerate parametric pumping in the three-wave and four-wave cases, where the pump frequency is either twice or equal to the signal frequency, respectively. We then derive expressions for the nondegenerate case where the pump frequency is not a multiple of the signal frequency, for which it becomes necessary to consider idler tones that occur. For the nondegenerate three-wave case, we present an intuitive picture for a parametric amplifier containing a flux-pumped SQUID where current at the signal frequency depends upon the load impedance at an idler frequency. This understanding provides insight and readily testable predictions of circuits containing flux-pumped SQUIDs.

LA eng

DO 10.1140/epjqt6

LK http://dx.doi.org/10.1140/epjqt6

LK http://publications.lib.chalmers.se/records/fulltext/202189/local_202189.pdf

OL 30