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Magnetic Resonance Force Microscopy with spin noise

Shesha Raghunathan, University of Southern California

(Session 5 : Friday from 5:00-7:00)

Abstract. A promising technique for measuring single electron spins is magnetic resonance force microscopy (MRFM), in which a micro-cantilever with a permanent magnetic tip is resonantly driven by a single oscillating spin. If the quality factor of the cantilever is high enough, this signal will be amplified over time to the point that it can be detected by optical or other techniques. An important requirement, however, is that this measurement process occur on a time scale short compared to any noise which disturbs the orientation of the measured spin. We describe a model of spin noise for the MRFM system, and show how this noise is transformed to become time-dependent by going to the usual rotating frame. We simplify the description of the spin-cantilever system by approximating the cantilever wavefunction as a gaussian wavepacket, and show that the resulting approximation closely matches the full quantum behavior. We then examine the problem of detecting the signal for a cantilever with thermal noise and spin with spin noise, deriving a condition for this to be a useful measurement.