# Bolometric technique for high-resolution broadband microwave spectroscopy of ultra-low-loss samples Academic Article

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### abstract

• A novel low temperature bolometric method has been devised and implemented for high-precision measurements of the microwave surface resistance of small single-crystal platelet samples having very low absorption, as a continuous function of frequency. The key to the success of this non-resonant method is the in-situ use of a normal metal reference sample that calibrates the absolute rf field strength. The sample temperature can be controlled independently of the 1.2 K liquid helium bath, allowing for measurements of the temperature evolution of the absorption. However, the instrument's sensitivity decreases at higher temperatures, placing a limit on the useful temperature range. Using this method, the minimum detectable power at 1.3 K is 1.5 pW, corresponding to a surface resistance sensitivity of $\approx$1 $\mu\Omega$ for a typical 1 mm$\times$1 mm platelet sample.

### authors

• Turner, PJ
• Broun, DM
• Kamal, Saeid
• Hayden, ME
• Bobowski, JS
• Harris, R
• Morgan, DC
• Preston, John Stewart
• Bonn, DA
• Hardy, WN

• January 2004