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Research Fellows Directory

Xavier Rojas

Dr Xavier Rojas

Research Fellow


Royal Holloway, University of London

Research summary

In general, quantum mechanical effects appear at the atomic scale and vanish at larger scale. This explains why we do not see them in our everyday life, where we appear to obey the laws of classical physics. Quantum mechanics theory predictions have been extensively and successfully tested. Still, exploring the frontier between the quantum and the classical world is, more than ever, of fundamental interest. Also, understanding this frontier may underpin the knowledge base to further develop high impact quantum technologies applications, such as quantum computers. In medical research, for example, where computing speed is crucial for delivering diagnosis and drug discovery results, quantum computers much faster than conventional computers would be greatly beneficial.

In quantum optomechanics, we tackle this problem by using photons (i.e. elementary particles of light) interacting many times with a mechanical resonator to detect its motion precisely. At room temperature, we observe a classical motion, but at low temperature we can detect quantum effects. This technique is a promising tool as it allows probing either side of the classical-quantum frontier. Yet, most fabricated resonators have strong limitations due to material losses, which prevents testing theoretical predictions.

The focus of my fellowship is to develop a new platform, to exploit superfluid helium as a mechanical element for quantum optomechanics. Supefluid helium is a very exotic material showing vanishing loss at low temperature. To build our mechanical resonator, we confine superfluid helium into a nanoscale acoustic cavity. We detect its motion via the photons of a superconducting microwave cavity embedded inside the acoustic cavity. This unique architecture offers unprecedented performances for an optomechanical system and high flexibility in design. If successful, this project would help us reveal the hidden secrets of the quantum world, while also driving technological breakthroughs.

Interests and expertise (Subject groups)

Grants awarded

Cavity optomechanics with superfluid 4He in a nanofluidic environment

Scheme: University Research Fellowship

Dates: Oct 2016 - Sep 2021

Value: £486,383.48