Download ATOMIC QUANTUM ENGINES IN OPTICAL TWEEZERS Prof. E. A.

ATOMIC QUANTUM ENGINES IN OPTICAL TWEEZERS
Prof. E. A. Hinds, Imperial College London
Dr G. Barontini, University of Birmingham
Background. Thermodynamics is fundamental to our understanding of many topics in science
and technology, including the operation of most machines and engines. As research pushes
towards ever smaller devices new quantum technology is increasingly about machines with
only one or a few atoms, and on this scale, standard thermodynamics fails because it has been
developed to describe large ensembles of particles. In addition, quantum effects become
important and the competition between quantum and thermal fluctuations plays a major role.
In this regime, then, even the most basic quantities such as "heat" and "work" need to be redefined, and thermodynamics itself must be reformulated on the basis of quantum mechanical
laws [1]. This brings exciting new opportunities for exploiting quantum-mechanical effects,
such as coherence and entanglement, to devise quantum engines that may outperform the best
classical engines [2].
The PhD project (at the University of Birmingham) is to build, characterize and develop the
first atomic quantum engines and to exploit the laws of quantum mechanics to push their
performance beyond the limits of classical machines. You will create an experiment using cold
atoms to test thermodynamic transformations and to develop engines at the single atom
quantum level. A single two-level atom will be trapped in an optical tweezer and will be
immersed in a heat bath of many atoms of a different species. All the parameters will be
completely controlled - the temperature and dimensionality of the bath, the interaction between
the single atom and the bath, and the internal and external degrees of freedom of the single
atom. With this exceptional control, it will be possible to make cyclic thermodynamic
transformations that realise quantum heat engines. This project aims to produce new results,
including realisations of the quantum Carnot, Otto and Diesel engines. These experiments will
help to develop an understanding of thermodynamics in the quantum realm and its practical
applications.
The MRes project is to design and build an optical system that can produce compact, robust
and versatile optical tweezers. Compactness is desirable for future practical applications, and
also because the tweezers must be integrated into an existing apparatus. To achieve this, the tip
of an optical fibre will be fused to create a microscopic lens. This will focus laser light to a
waist of about 1 μm at a distance of about 1 mm from the tip, where atoms will be trapped in a
very small volume by the optical dipole force. Because of a well-known blockade mechanism
[3], the trap will not hold more than one atom. Machining directly on the tip guarantees nearperfect alignment of the trap, an advantage over conventional optics susceptible to small
misalignments. Additionally, the fibre is broad-band, so can be used to overlap light of several
different wavelengths on the trapped atom, and to collect fluorescence, exploiting the high
numerical aperture subtended by the tip. The candidate will work at the University of
Birmingham to develop a method to produce a lensed fibre using an advanced arc fusion fibre
splicer. The candidate will then test and characterize the beam produced by the lensed fibre to
ensure that it meets the requirements outlined above.
[1] S. Vinjanampathy and J. Anders, Contemp. Phys., 57, 1 (2016)
[2] Raam Uzdin, Amikam Levy, and Ronnie Kosloff, Phys. Rev. X 5, 031044 (2015); Marlan O. Scully,
M. Suhail Zubairy, Girish S. Agarwal, Herbert Walther, Science 299, 862 (2003); J Jaramillo, M Beau
and A del Campo, New J. Phys. 18 075019 (2016)
[3] A. M. Kaufman, B. J. Lester, and C. A. Regal, Phys. Rev. X 2, 041014 (2012)