**The research in context**
Technology is continuously miniaturizing, and as it reaches the nanoscale we face unique challenges. How do we control such small objects? What happens when temperature fluctuations have the same energy scale as our devices? From the other direction, advances in the quantum physics of a few atoms, ions, and solid-state qubits mean that we increasingly wish to scale up quantum systems, or interface them with nanoscale technology.
Nano- and micro-mechanical devices have been controlled at the quantum level in recent years, an amazing advance allowing even entanglement between light and mechanical motion. However, all such small systems are limited by unavoidable environmental effects, such as thermal contact with the surroundings and energy dissipation through strain. This limits the participation of mechanical devices in both classical and quantum technologies.
By using a levitated nanoparticle as the mechanical device, these problems are overcome. LEVELECTRO will pioneer the integration of levitated nano-objects with electronic circuits, allowing electrical cooling and networking. This ultra-low dissipation system offers exquisite force sensitivity.
LEVELECTRO will explore new regimes of physics, by working in extreme vacuum, elucidating thermodynamics on the nanoscale. This unique research will enable levitated nano-objects to participate in quantum technologies as long-lived quantum storage devices, and as high-fidelity transducers between optical and electronic quantum signals.
**Aims and Applications**
*Aim 1 - All-electrical nanoparticle control platform: LEVELECTRO introduces a new platform, where a levitated nanoparticle is coupled to an electrical circuit, founding the field levitated electromechanics (LE). LE will allow fully electronic control and cooling of the motion of nanoparticles, avoiding the detrimental scattering and absorption encountered in optical levitation. Electrical cooling removes thermal energy which masks the sensitivity of the levitated particles to their environment, hence cooling boosts the ability for the LE platform to behave as a sensor.
*Aim 2 - Ultra-low dissipation networked device: Nanoparticles levitated in vacuum are predicted to have the highest mechanical quality factor of any mechanical object. Such a levitated nanoparticle acts like a little pendulum clock, and in principle if you give it a kick it would take months for it to ring-down. Such behaviour hasn't been realised in optical systems, due to the instability of nanoparticles in optical traps at low pressures, and the fact that the fundamental noise on the light field leads to some additional damping.
The LE system doesn't suffer from these limitations. The potential to provide an electrically networked, ultra-high quality factor oscillator, promises to challenge quartz crystal oscillator technology, which is ubiquitous in communications, navigation, and signal processing, and enable the detection of tiny forces.
*Aim 3 - Ultra-low dissipation quantum device: LEVELECTRO will explore Levitated Cavity Quantum Electromechanics (LCQE) theory, where a levitated charged particle is coupled to quantum microwave cavities. Regular cavity quantum electromechanical systems are at the forefront of quantum technologies, but are limited by a loss of energy (dissipation) from the mechanical element to the environment. LCQE overcomes this problem, promising ultra-low dissipation operation, deep quantum cooling, and the storage of quantum information for tens of seconds.
It is also possible to combine the LCQE system with a levitated cavity quantum optomechanical one, enable the conversion of quantum states of light, to quantum electrical signals. One can foresee the conversion of freely propagating quantum states of light into highly accessible and controllable quantum electrical signals, a much-needed quantum transducer acting as a node in a quantum information network.
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