Final Report Summary - MICROCOLD (Microscopically designed environments for cold atoms)
The field of ultracold atom research has grown into a mature area of physics very quickly after its initial successes of laser cooling and the seminal achievement of Bose-Einstein condensation in dilute atomic vapors only a few years later. Today, the state of the art in the field is such that applications in a numerous directions are being pursued and/or within reach in many domains. On the one hand, very general questions in physics can be addressed, such as controlled preparation and studies of dynamics of single or few particle quantum systems. On the other hand, technological applications of cold atom systems are being developed, for example in the development of precision measurements based on atomic clocks or atom interferometers.
This project focused on establishing a new laboratory based research programme for the use of microscopic traps based on atom chips for precise and spatially highly resolved control of ultracold degenerate and near degenerate quantum gases. The scope of the experimental proposal includes two main research directions that are closely intertwined from the technical point of view, while aiming at quite different physical goals. The first set of planned experiments will address fundamental questions in general many body physics where the unique possibilities of microscopic trapping and controlling fields near the surface of microchips will be exploited to create specific non-trivial confinement geometries and topologies as well as spatially and temporally varying environments for studies of dynamical phenomena. The second line of experiments will also be based on the precise and flexible control of cold atoms that is possible near surfaces. However, in this case rather than studying the properties of the atomic systems themselves, the roles will be reversed here, and the atoms will be used to measure processes that happen in the near-by surfaces. Specific objectives of the research are:
Many-body physics in non-trivial microscopically tailored environments: This part of the project utilises the unique possibility on atom chips to custom design potentials, topologies, and interaction strengths between atoms constituting a many body system. The main long-term objectives with initial results at the end of the funding period are:
Studies of cold quantum gases in multiply connected traps, such as rings, cylinders and tori, with particular emphasis on low dimensional systems with periodic boundary conditions
Investigations of non-equilibrium dynamics of quantum gases in time-dependent environments.
Research along these lines will provide scientific added value as by providing new experimental generic model systems that provide a direct testing ground for general many-body theories. The fundamental interest in such studies extends beyond the realm of atomic physics to condensed matter and particle physics, even analogies with cosmology are within reach.
Ultracold atoms as magnetic field sensors: In this second part of the project, the aim was to further develop a magnetic and electric field microscope that whose operation we demonstrated in a proof-of-principle fashion in an earlier project. In this work we could show that ultracold degenerate gases are well suited to map minute variations in magnetic and electric fields with high spatial resolution. In our published work we demonstrated that we could reach a sensitivity of a few nT at a few microns resolution. These promising results trigger further interest in the technique and its development as well as a drive towards applying the microscope in order to study surface processes with unprecedented precision and accuracy. Specific objectives with demonstration experiments as a final result of this project include:
Further development of cold atom field microscopy with the goal of even higher sensitivity and spatial resolution
High resolution measurements of transport phenomena in two-dimensional electron gases
Magnetic field measurements in the vicinity of magnetic semiconductor materials
This part of the project adds technological interest to the fundamental studies. Here, details of microfabrication technology can be tested as well as knowledge on details of processes in semiconductors of various kinds can be gained. The interdisciplinary character of this research on the boundary between atomic, semiconductor, condensed matter physics and microfabrication technology is apparent.
This research programme is set within the newly founded Midlands Ultracold Research Centre (MUARC). During the last year of the funding period, all activities were centered around completing the infrastructure necessary and to begin the experiments outlined above. After the full completion of laboratory refurbishment work including a number of repairs, the conditions for experimental work including appropriate air conditioning units are fulfilled. The construction of three independent cold atom setups has been concluded, one of which will be of particular relevance for the long-term scientific goals outlined in this project. A fourth setup has now been constructed in order to more efficiently carry out the ongoing measurements by distributing them over two apparatus. In the original setup laser cooled cold samples of rubidium-87 are routinely produced and stored magnetically in a subsequent step. Together with our collaborators, in particular at Ben-Gurion University in Israel, we have fabricated a series of atom chips, one of which has been integrated to the setup, and experiments with it have begun
This project focused on establishing a new laboratory based research programme for the use of microscopic traps based on atom chips for precise and spatially highly resolved control of ultracold degenerate and near degenerate quantum gases. The scope of the experimental proposal includes two main research directions that are closely intertwined from the technical point of view, while aiming at quite different physical goals. The first set of planned experiments will address fundamental questions in general many body physics where the unique possibilities of microscopic trapping and controlling fields near the surface of microchips will be exploited to create specific non-trivial confinement geometries and topologies as well as spatially and temporally varying environments for studies of dynamical phenomena. The second line of experiments will also be based on the precise and flexible control of cold atoms that is possible near surfaces. However, in this case rather than studying the properties of the atomic systems themselves, the roles will be reversed here, and the atoms will be used to measure processes that happen in the near-by surfaces. Specific objectives of the research are:
Many-body physics in non-trivial microscopically tailored environments: This part of the project utilises the unique possibility on atom chips to custom design potentials, topologies, and interaction strengths between atoms constituting a many body system. The main long-term objectives with initial results at the end of the funding period are:
Studies of cold quantum gases in multiply connected traps, such as rings, cylinders and tori, with particular emphasis on low dimensional systems with periodic boundary conditions
Investigations of non-equilibrium dynamics of quantum gases in time-dependent environments.
Research along these lines will provide scientific added value as by providing new experimental generic model systems that provide a direct testing ground for general many-body theories. The fundamental interest in such studies extends beyond the realm of atomic physics to condensed matter and particle physics, even analogies with cosmology are within reach.
Ultracold atoms as magnetic field sensors: In this second part of the project, the aim was to further develop a magnetic and electric field microscope that whose operation we demonstrated in a proof-of-principle fashion in an earlier project. In this work we could show that ultracold degenerate gases are well suited to map minute variations in magnetic and electric fields with high spatial resolution. In our published work we demonstrated that we could reach a sensitivity of a few nT at a few microns resolution. These promising results trigger further interest in the technique and its development as well as a drive towards applying the microscope in order to study surface processes with unprecedented precision and accuracy. Specific objectives with demonstration experiments as a final result of this project include:
Further development of cold atom field microscopy with the goal of even higher sensitivity and spatial resolution
High resolution measurements of transport phenomena in two-dimensional electron gases
Magnetic field measurements in the vicinity of magnetic semiconductor materials
This part of the project adds technological interest to the fundamental studies. Here, details of microfabrication technology can be tested as well as knowledge on details of processes in semiconductors of various kinds can be gained. The interdisciplinary character of this research on the boundary between atomic, semiconductor, condensed matter physics and microfabrication technology is apparent.
This research programme is set within the newly founded Midlands Ultracold Research Centre (MUARC). During the last year of the funding period, all activities were centered around completing the infrastructure necessary and to begin the experiments outlined above. After the full completion of laboratory refurbishment work including a number of repairs, the conditions for experimental work including appropriate air conditioning units are fulfilled. The construction of three independent cold atom setups has been concluded, one of which will be of particular relevance for the long-term scientific goals outlined in this project. A fourth setup has now been constructed in order to more efficiently carry out the ongoing measurements by distributing them over two apparatus. In the original setup laser cooled cold samples of rubidium-87 are routinely produced and stored magnetically in a subsequent step. Together with our collaborators, in particular at Ben-Gurion University in Israel, we have fabricated a series of atom chips, one of which has been integrated to the setup, and experiments with it have begun