Towards the study of quantum engines in 41K-87Rb Bose-Bose Mixtures

Lead Research Organisation: University of Birmingham
Department Name: School of Physics and Astronomy


The particular questions this project aims to address can be summarised in the following four points:

1. Understanding the thermalization of the single particle with a bath - Thermalization and equilibration are usually treated following two different approaches, one originating from quantum optics and the other from quantum information theory. The provision of a (currently lacking) unified understanding of such fundamental phenomena is the core of this objective.

2. Realisation of simple quantum thermo-machines - Realizing quantum engines requires to realize quantum thermodynamic transformations and combine them in cycles that can be run repeatedly. Our experiment will be able to realize Quantum Carnot, Otto and Diesel engines.

3. Quantum engineering of working medium - Quantum states are "richer" than classical ones. They feature quantum coherences from which one can extract work. Work can also be extracted from quantum correlations.

4. Exploration of prototype many-particle quantum engines - Many-body effects can also be exploited to build more efficient engines. A working fluid of interacting quantum particles has been proven to produce more power than the sum of single-particle engines.

Ultra cold atoms mixtures will be used in order to achieve the required low temperatures and degree of control over the system. In particular, the chosen atomic species for this experiment are 41K, which will be our single atom quantum engine, and 87Rb, which will act as a thermal bath. These two alkali metal can be cooled via laser cooling and a posterior evaporative cooling to the ultra cold regime. Furthermore, these two species present a very convenient interspecies Feshbach resonance that allows us to tune the interaction between them. In the current state, we are able to reach the ultra cold regime of 87Rb and the near ultra cold regime of 41K. After this, we will have to work in the novel methods to manipulate the atoms which are summarised in the following points:

1. Fibre-atom interfaces and fibre-based technology - Quantum systems integrated with optical fibres offer unprecedented flexibility and reconfiguration opportunities. A large number of quantum experiments have pursued such direction to interface quantum systems with micro-fabricated fibres, including atoms, mechanical resonators, ions, carbon nanotubes, quantum dots and wells and NV-centres in diamonds. Such versatility is promoting fibre-based systems as very exciting technological platforms.

2. Realizing optical tweezers for single-atom manipulations - This is currently one of the hottest topics in the area of ultra-cold atoms. This technique is promising to realize arbitrary atom arrays atom by atom, and has also proven to be very effective in understanding few body physics and building quantum sensing devices. One of the most challenging yet tantalising directions is to realize optical tweezers for atoms of different species. This will demonstrate the first species-selective optical tweezer, thus contributing to this exciting quest.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509590/1 01/10/2016 30/09/2021
1843543 Studentship EP/N509590/1 01/10/2016 31/03/2020 Jorge Mellado Munoz
Description We are developing an experimental setup for the research of quantum thermodynamics. This means that we are aiming to study the thermodynamic properties of systems in which the quantum effects are not negligible. In our case, our setup is able to bring two atomic species (87Rb and 41K) to the ultra-cold regime in which the quantum effects become dominant. In order to cold down both species we are using the usual laser cooling (using the D2 line of both species) and a posterior evaporative cooling process in a far red-detuned crossed dipole trap.

Our plan is to use an ultra-cold cloud of 87Rb as our thermal reservoir and one atom of 41K as our engine. The chosen atomic species possess low field hetero nuclear Feshbach resonances which means that the interaction between them can be easily tuned with low magnetic fields from repulsive to attractive or even no interaction at all. Together with this we will have to design an species-selective optical tweezer using a wavelength that will allow us to trap and manipulate a single 41K atom without affecting the 87Rb.

It is important to mention that one of the milestones of this project is the achievement of the first dual-species all-optical Bose-Einstein condensate.
Exploitation Route The findings will be very fundamental, however the fact of being able to extend the thermodynamics from the classic world to the quantum world will have implications. This is because nowadays the main part of the technological research tends towards smaller length scales. Consequently, some fields in which this research will impact are the computing industry, biological research and any area in the nano-scale domain.
Sectors Digital/Communication/Information Technologies (including Software),Manufacturing, including Industrial Biotechology