Abstract: Inflationary cosmology postulates that the Universe underwent a period of accelerated expansion in the first $10^{-30}$,s after the Big Bang. Inflationary models are attractive because they solve outstanding problems in cosmology: the origin of structure, the absence of monopoles, and the horizon and flatness problems. Although inflation is consistent with existing data, the fundamental physics responsible for it is unknown. Cosmic Microwave Background (CMB) measurements promise to verify one of the predictions of inflation: odd-parity polarization modes (B modes). CMB B modes have not yet been detected. I will describe the QUIET instrument, how it mitigates systematic contamination, and results from the first season of observation at 43 GHz. QUIET sets one of the best limits to date on inflationary B modes (r < 2.2). Moreover the unique QUIET design leads to the lowest levels of systematic contamination in the inflationary signal reported by any CMB polarization experiment. This suppression of systematic errors demonstrates the technology for a next-generation experiment. I will also report the status of analysis of the QUIET second-season 95-GHz data.

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