Periodic Reporting for period 3 - MesoPhone (Vibrating carbon nanotubes for probing quantum systems at the mesoscale)
Reporting period: 2022-03-01 to 2023-08-31
Many fascinating quantum behaviours occur on a scale that is intermediate between individual particles and large ensembles. It is on this mesoscopic scale that collective properties, including quantum decoherence, start to emerge.
This project will use vibrating carbon nanotubes – like guitar strings just a micrometre long – as mechanical probes in this intermediate regime. Nanotubes are ideal to explore this region experimentally, because they can be isolated from thermal noise; they are deflected by tiny forces; and they are small enough that quantum jitter significantly affects their behaviour. To take advantage of these properties, I will integrate nanotube resonators into electromechanical circuits that allow sensitive measurements at very low temperature.
This project will use vibrating carbon nanotubes – like guitar strings just a micrometre long – as mechanical probes in this intermediate regime. Nanotubes are ideal to explore this region experimentally, because they can be isolated from thermal noise; they are deflected by tiny forces; and they are small enough that quantum jitter significantly affects their behaviour. To take advantage of these properties, I will integrate nanotube resonators into electromechanical circuits that allow sensitive measurements at very low temperature.
We have installed two new refrigerators that can reach the very low temperatures required for this project, and instrumented them with sensitive electronic amplifiers to detect nanotube vibrations. Our main scientific discoveries so far have been:
- We have shown how to use a superconducting amplifier to measure very small radio-frequency signals.
- This enabled us to measure self-generated oscillations of a vibrating nanotube, work that was covered in newspapers including the i, Spiegel, and Guitar World.
- We have shown how an artificially intelligent machine can learn the behaviour of a nanoscale electronic device and use this information to optimise it for a purpose determined by the human experimenter.
- We have used a nanomechanical resonator (in this case a silicon nitride drum) to study the thermodynamic cost of timekeeping.
- We have used a single-electron transistor as an electronic refrigerator operating inside a cryostat.
- We have shown how to use a superconducting amplifier to measure very small radio-frequency signals.
- This enabled us to measure self-generated oscillations of a vibrating nanotube, work that was covered in newspapers including the i, Spiegel, and Guitar World.
- We have shown how an artificially intelligent machine can learn the behaviour of a nanoscale electronic device and use this information to optimise it for a purpose determined by the human experimenter.
- We have used a nanomechanical resonator (in this case a silicon nitride drum) to study the thermodynamic cost of timekeeping.
- We have used a single-electron transistor as an electronic refrigerator operating inside a cryostat.
Our self-excited carbon nanotube resonator constitutes a mechanical analogue of a laser and has allowed us to study several non-trivial effects of feedback, quantum tunneling. and non-linearity.
The expected results until the end of the project are:
- A new kind of quantum interferometer, based on a virating carbon nanotube integrated into a superconducting circuits. This will address a longstanding question of physics: can a moving object, containing millions of particles, exist in a superposition of states?
- A new viscometer to study superfluid helium 3 – the mysterious state of matter that may emulate the interacting quantum fields of the early universe. By measuring an immersed nanotube viscometer, I will be able to measure the behaviour of superfluid excitations on a scale where bulk superfluidity begins to break down.
- An ultra-sensitive magnetic force sensor. This offers a way to perform nuclear magnetic resonance on a chip, ultimately creating a microscopy tool that could image for example single viruses.
The expected results until the end of the project are:
- A new kind of quantum interferometer, based on a virating carbon nanotube integrated into a superconducting circuits. This will address a longstanding question of physics: can a moving object, containing millions of particles, exist in a superposition of states?
- A new viscometer to study superfluid helium 3 – the mysterious state of matter that may emulate the interacting quantum fields of the early universe. By measuring an immersed nanotube viscometer, I will be able to measure the behaviour of superfluid excitations on a scale where bulk superfluidity begins to break down.
- An ultra-sensitive magnetic force sensor. This offers a way to perform nuclear magnetic resonance on a chip, ultimately creating a microscopy tool that could image for example single viruses.