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Dispersive magnetometry with a quantum limited SQUID parametric amplifier

M. Hatridge, R. Vijay, D. H. Slichter, John Clarke, and I. Siddiqi
Phys. Rev. B 83, 134501 – Published 4 April 2011
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Abstract

There is currently fundamental and technological interest in measuring and manipulating nanoscale magnets, particularly in the quantum coherent regime. To observe the dynamics of such systems one requires a magnetometer with not only exceptional sensitivity but also high gain, wide bandwidth, and low backaction. We demonstrate a dispersive magnetometer consisting of a two-junction superconducting quantum interference device (SQUID) in parallel with an integrated, lumped-element capacitor. Input flux signals are encoded as a phase modulation of the microwave drive tone applied to the magnetometer, resulting in a single quadrature voltage signal. For strong drive power, the nonlinearity of the resonator results in quantum limited, phase sensitive parametric amplification of this signal, which improves flux sensitivity at the expense of bandwidth. Depending on the drive parameters, the device performance ranges from an effective flux noise of 0.29 μΦ0Hz1/2 and 20 MHz of signal bandwidth to a noise of 0.14 μΦ0Hz1/2 and a bandwidth of 0.6 MHz. These results are in excellent agreement with our theoretical model.

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  • Received 11 November 2010

DOI:https://doi.org/10.1103/PhysRevB.83.134501

©2011 American Physical Society

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Harnessing nonlinearity for linear measurements

Published 4 April 2011

Researchers develop a new type of superconducting quantum interference device (SQUID) with significantly enhanced sensitivity and bandwidth, which can function as a general-purpose magnetic sensor.

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Authors & Affiliations

M. Hatridge1, R. Vijay2, D. H. Slichter2, John Clarke1, and I. Siddiqi2

  • 1Department of Physics, University of California, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 2Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA

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Issue

Vol. 83, Iss. 13 — 1 April 2011

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