Vacuum Tunneling Probe: A Nonreciprocal, Reduced-Back-Action Transducer

Abstract

The vacuum tunneling probe used in the scanning tunneling microscope represents a new class of nonreciprocal electromechanical transducers. Nonreciprocity implies reduced back action and consequently increased sensitivity over conventional, reciprocal transducers. A vacuum tunneling probe may reach the quantum limit for a measurement of the position of a macroscopic mechanical oscillator even with use of a non-quantum-limited amplifier. The quantum limit is enforced by the momentum shot noise associated with the tunneling current.

Suppression of the stochastic fluctuations of suspended nanowires by temperature-induced single-electron tunneling

“…Regarding this point, it has been argued since a long time ago that the STM (combined with a current amplifier) can provide the basic building block for a quantumlimited position displacement sensor. The tunneling current that can be measured at the output of such a device contains information about the displacement of the mechanical system under investigation but, at the same time, perturbs it with a very small back-action force, this being mainly due to the random momentum transfer associated with the tunneling electrons [15].…”

Introduction to Microwave Cavity Optomechanics

“…These schemes include transducing motion into a changing capacitance or inductance [19], which would then result in a changing current or voltage. A related scheme envisioned coupling motion to a nanometer-sized gap between electrodes, modulating a tunneling current [20]. Rather than detect directly the current or voltage created by a time varying capacitance, several groups pursue schemes where mechanical motion alters the resonance frequency of a literal microwave cavity [21,22] (also see Ref.…”

Super-rolloff electron tunneling transduction of nanomechanical motion using frequency downmixing

“…Numerous methods for displacement detection in NEMS have been developed, such as optical interferometry, 6-9 magnetomotive, 10 capacitive, 11 and piezoresistive 12 techniques. Scanning tunneling microscopy ͑STM͒ based on electron tunneling is also a promising method to measure small displacement because the tunneling current is very sensitive to the change in distance [13][14][15] between the tip of a STM and the sample surface. Its fundamental frequency limit, I T / e ͑where e is the electron charge͒, can reach the gigahertz range.…”