Intrinsic noise properties of atomic point contact displacement detectors

Abstract

We measure the noise added by an atomic point contact operated as a displacement detector. With a microwave technique, we increase the measurement speed of atomic point contacts by a factor of 500. The measurement is then fast enough to detect the resonant motion of a nanomechanical beam at frequencies up to 60 MHz and sensitive enough to observe the random thermal motion of the beam at 250 mK. We demonstrate a shot-noise limited imprecision of $2.3\pm 0.1fm/\sqrt{\mathrm{Hz}}$ and observe a $78\pm 20aN/\sqrt{\mathrm{Hz}}$ backaction force, yielding a total uncertainty in the beam's displacement that is $42\pm 9$ times the standard quantum limit.

5 pages, 4 figures, to appear in Physical Review Letters

References in corpus (2)

• A tunable carbon nanotube electromechanical oscillator
• Quantum-Limited Position Detection and Amplification: A Linear Response Perspective

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