The general theme of this group is to explore the interface between quantum physics and nanotechnology.

Quantum physics deals with the extremely tiny: photons, electrons, atoms… with researchers continuously pushing the science into larger and larger systems to see if there’s a point at which quantum effects break down. Conversely, nanophysics deals with our continuous miniaturization of technology, and the incredible utility that brings. These two sciences are on a collision course, which we explore here in the Levitated Nanophysics group.

We levitate nanoparticles, and control their motion, looking for quantum effects and inspiring new technology. A summary of our research can be found in the video below:

Rotational Optomechanics

Optomechanics concerns the control of mechanical motion with light. There is surely no tool as flexible as light, and few technologies over which we have so much control. This means that it is possible to control the quantum motion of quite massive objects (micrometres) via light.

It is also possible to levitate nano-scale objects, just as spheres of glass, using focussed light beams. At this point their motional energy can be “cooled”, and hopefully quantum effects can be observed in the motion of objects almost big enough to see!

The Levitated Nanophysics group will exploit the optical control of nanoparticle rotation, to observe new quantum phenomena, and build sensitive devices for detecting particle collisions, gas flows, torque and even gyroscopic effects.

Key publications:
Full Rotational Control of Levitated Silicon Nanorods
Stefan Kuhn, Alon Kosloff, Benjamin A. Stickler, Fernando Patolsky, Klaus Hornberger, Markus Arndt, James Millen
Optica 4, 356-360 (2017)
Optically driven ultra-stable nanomechanical rotor
Stefan Kuhn, Benjamin A. Stickler, Alon Kosloff, Fernando Patolsky, Klaus Hornberger, Markus Arndt, James Millen
Nature Communications 8, 1670 (2017)
Orientational quantum revivals of nanoscale rotors
Benjamin A. Stickler, Birthe Papendell, Stefan Kuhn, James Millen, Markus Arndt, Klaus Hornberger
arXiv:1803.01778 (2018)

Key funding:
ERC Starting Grant 803277
01/02/2019 – 31/07/2024

Royal Society Research Grant RGS\R1\201096
31/03/2020 – 31/03/2021

Key partners:
Markus Arndt @ University of Vienna
Klaus Hornberger @ University of Duisberg-Essen
Stefan Kuhn @ University of Vienna
Fernando Patolsky @ Tel Aviv University
Benjamin Stickler @ University of Duisberg-Essen

Levitated Electromechanics

Electromechanics concerns the control of mechanical motion via its coupling to an electrical circuit. Chip-based electromechanical systems are leading quantum technologies, allowing entanglement between different circuit-signals, quantum squeezing, and the coherent conversion of signals between different frequency regimes.

The Levitated Nanophysics group will pioneer the electromechanical control of charged levitated particles, which are levitated by electric fields. This will exploit the incredible mechanical properties of levitated particles to create new signal processing technologies; a levitated quartz crystal oscillator.

We also study the quantum physics of this system, to explore the potential of building a quantum-mechanical circuit networked device.

Key publications:
Levitated electromechanics: all-electrical cooling of charged nano- and micro-particles
Daniel Goldwater, Benjamin A. Stickler, Lukas Martinetz, Tracy E. Northup, Klaus Hornberger & James Millen
Quantum Science & Technology 4, 024003 (2019)

Key funding:
EPSRC New Investigator Award EP/S004777/1
01/08/2018 – 31/07/2021

Key partners:
Benjamin Stickler @ University of Duisberg-Essen
Tracy Northup @ University of Innsbruck

Nanothermodynamics

Thermodynamics is one of the most surprising and useful theories ever conceived; we can describe the behaviour of a room full of air molecules (>10^26 objects with many degrees of freedom) with three numbers (pressure, volume, temperature).

This theory is fundamentally a theory of averages, which is fine when dealing with countless billions of particles! At the nanoscale, where many technologies are beginning to operate, statistical fluctuations can dominate the dynamics.

In the Levitated Nanophysics group we will study this science in unexplored regimes. We will look at the thermodynamics of rotation, enabling interrogation over unconstrained timescales. We will use our unique electromechanical system to explore thermodynamics in the regime of deep vacuum.

Key publications:
Levitated Nanoparticles for Microscopic Thermodynamics—A Review.
Jan Gieseler and James Millen
Entropy 20, 326 (2018)

Perspective: Quantum Thermodynamics.
James Millen & Andre Xuereb
New J. Phys 18, 011002 (2016)

Nanoscale temperature measurements using non-equilibrium Brownian dynamics of a levitated nanosphere.
J Millen, T Deesuwan, P Barker, J Anders
Nature Nanotechnology 9, 425–429 (2014)

Key funding:
ERC Starting Grant 803277
01/02/2019 – 31/07/2024

Key partners:
Dr. Janet Anders @ University of Exeter

Current Research Funding

LeviTeQ: Levitated Nanoparticles for Technology and Quantum Nanophysics: New frontiers in physics at the nanoscale
ERC Starting Grant 803277
01/02/2019 – 31/07/2024 (£1.35M)

LeviNet: Levitation Network for Advanced Quantum Technologies
EPSRC International Quantum Technologies Network Grant EP/W02683X/1
14/02/2022 – 13/02/2025 (£427,000)

L-MEMS: Development of a Levitated Micro Electro Mechanical Sensor
EPSRC Impact Acceleration Account (IAA)
01/08/2021 – 28/02/2022 (£49,000)

Past Research Funding

LeviTech: Levitated Particles as the heart of miniaturized sensing technologies
ERC Proof of Concept grant 957463
01/08/2020 – 01/02/2022 (£131,000)

LevElectro: Levitated Electromechanics: All-Electrical Nanoscale Control and Cooling
EPSRC New Investigator Award EP/S004777/1
01/08/2018 – 31/07/2021 (£387,989)

Doing more with less: using structured light for low noise sensors
Royal Society Research Grant RGS\R1\201096
31/03/2020 – 31/03/2021 (£20,000)