New manuscripts: An oscillating nanotube, a radio-frequency drum, and a machine to run experiments

Our recent experiments have led to three new papers on the arXiv:

  • A coherent nanomechanical oscillator driven by single-electron tunnelling by Yutian Wen describes a carbon nanotube oscillator driven by an electrical current. When we measure a tiny moving object, for example by detecting changes in its conductance, we know the measurement must also disturb its state. Usually this disturbance is incoherent, i.e. without any regularity in time. This paper measures a vibrating carbon nanotube and shows that measurement backaction can make it oscillate coherently. We show that the device behaves in many ways like a laser, but using sound instead of light.
  • Radio-frequency optomechanical characterization of a silicon nitride drum by Anna Pearson from the Ares group measures a different kind of nanomechanical device, a vibrating silicon nitride membrane. These “nano-drums” are workhorses of optomechanics, especially at low temperatures and in optical interferometers. This paper shows how to use them for optomechanics at room temperature in a radio-frequency circuit.
  • Efficiently measuring a quantum device using machine learning by Dominic Lennon and Hyungil Moon applies neural networks to the challenge of running experiments in real time. Future quantum computers will contain millions of qubits. In current experiments, every qubit is optimised by hand. This paper puts a machine in control of the experiment, and shows that it can quickly characterise a quantum dot by efficiently selecting what to measure.

    A coherent nanomechanical oscillator driven by single-electron tunnelling (a) Oscillator schematic. (b) Realisation in a vibrating carbon nanotube. (c) Radio-frequency emission for device configurations below and above threshold, showing the onset of self-excited oscillations.