Periodic Reporting for period 4 - TOPODY (Exploring topological matter with atomic Dysprosium)
Reporting period: 2022-07-01 to 2024-06-30
Topology has stepped into an increasing number of areas in physics, particularly through the concept of topological phases of matter. These states of matter are characterized by the robustness of certain physical quantities under small perturbations of the system. They also exhibit specific transport properties located at the boundary of the system, which are protected by the underlying topology. These unique characteristics are expected to trigger various applications, from the definition of physical standards to the development of robust quantum computing.
In condensed matter physics, electronic systems exhibiting a quantized Hall conductivity constitute the most famous example of topological systems. A wide variety of topological systems have been discovered, from integer and fractional Hall states to topological insulators and superconductors. However, condensed matter systems are often plagued by undesired effects due to disorder or difficulties in accessing and manipulating single electrons. This motivates the need for developing alternative platforms, such as atomic gases or photonic systems.
In the TOPODY project, researchers have developed a new approach using a platform of ultracold dysprosium atoms. The key development was the use of synthetic dimensions encoded in the giant spin of dysprosium atoms, which gave them flexibility to create artificial gauge fields. This allowed them to reproduce the equivalent of a two-dimensional quantum Hall system with local control. They have also generalized the quantum Hall effect to more exotic geometries, including a cylinder and a system effectively evolving in four dimensions, which do not have equivalents in solid-state materials. Additionally, the flexibility of the light-spin coupling used to generate the gauge fields has enabled them to probe entanglement properties, which play a fundamental role in topological quantum systems.
The researchers have also made important steps towards the realization of strongly-correlated topological systems, which involve more complex correlations between particles. These achievements demonstrate the importance of ultracold atomic systems for exploring fundamental questions in condensed matter physics. They may lead to the realization of even more complex systems, such as those exhibiting the emergence of low-energy excitations with anyonic character, which could serve as a starting point for developing new types of quantum computation protocols.
In condensed matter physics, electronic systems exhibiting a quantized Hall conductivity constitute the most famous example of topological systems. A wide variety of topological systems have been discovered, from integer and fractional Hall states to topological insulators and superconductors. However, condensed matter systems are often plagued by undesired effects due to disorder or difficulties in accessing and manipulating single electrons. This motivates the need for developing alternative platforms, such as atomic gases or photonic systems.
In the TOPODY project, researchers have developed a new approach using a platform of ultracold dysprosium atoms. The key development was the use of synthetic dimensions encoded in the giant spin of dysprosium atoms, which gave them flexibility to create artificial gauge fields. This allowed them to reproduce the equivalent of a two-dimensional quantum Hall system with local control. They have also generalized the quantum Hall effect to more exotic geometries, including a cylinder and a system effectively evolving in four dimensions, which do not have equivalents in solid-state materials. Additionally, the flexibility of the light-spin coupling used to generate the gauge fields has enabled them to probe entanglement properties, which play a fundamental role in topological quantum systems.
The researchers have also made important steps towards the realization of strongly-correlated topological systems, which involve more complex correlations between particles. These achievements demonstrate the importance of ultracold atomic systems for exploring fundamental questions in condensed matter physics. They may lead to the realization of even more complex systems, such as those exhibiting the emergence of low-energy excitations with anyonic character, which could serve as a starting point for developing new types of quantum computation protocols.
The first objective of the research was the production of quantum degenerate gases, which is a prerequisite for further scientific projects. The researchers developed a novel laser cooling scheme for dysprosium atoms held in an optical dipole trap, which allowed them to produce Bose-Einstein condensates of dysprosium atoms.
The realization of topological quantum matter is based on the simulation of gauge fields using suitable light-spin interaction. The researchers subjected the atoms to light fields close to a narrow optical transition, which led to a non-linear spin dynamics. This allowed them to generate non-classical spin states and demonstrate an increased sensitivity to external magnetic fields compared to classical counterparts.
The researchers then extended the light-spin interaction to induce a coupling between the atomic motion and its electronic spin state, known as spin-orbit coupling. They used the large spin of dysprosium (J = 8) as a synthetic dimension, effectively creating a two-dimensional system with one spatial dimension and a synthetic dimension featuring sharp edges. This system is analogous to a quantum Hall system in a finite geometry, exhibiting chiral edge modes and a quantized Hall response in the bulk.
The researchers further extended the protocol to generate quantum Hall systems in exotic geometries, including a cylinder and a system effectively evolving in four dimensions. These systems exhibit specific properties that do not have equivalents in solid-state materials. Additionally, the flexibility of the light-spin coupling was used to probe entanglement properties, which play a fundamental role in topological quantum systems.
Finally, the researchers performed important steps towards the realization of strongly-correlated topological systems, which could exhibit even more complex behavior.
The scientific results obtained in TOPODY have led to the publication of 11 scientific articles and two pre-prints. The results have also been presented in many scietific workshops and conferences.
The realization of topological quantum matter is based on the simulation of gauge fields using suitable light-spin interaction. The researchers subjected the atoms to light fields close to a narrow optical transition, which led to a non-linear spin dynamics. This allowed them to generate non-classical spin states and demonstrate an increased sensitivity to external magnetic fields compared to classical counterparts.
The researchers then extended the light-spin interaction to induce a coupling between the atomic motion and its electronic spin state, known as spin-orbit coupling. They used the large spin of dysprosium (J = 8) as a synthetic dimension, effectively creating a two-dimensional system with one spatial dimension and a synthetic dimension featuring sharp edges. This system is analogous to a quantum Hall system in a finite geometry, exhibiting chiral edge modes and a quantized Hall response in the bulk.
The researchers further extended the protocol to generate quantum Hall systems in exotic geometries, including a cylinder and a system effectively evolving in four dimensions. These systems exhibit specific properties that do not have equivalents in solid-state materials. Additionally, the flexibility of the light-spin coupling was used to probe entanglement properties, which play a fundamental role in topological quantum systems.
Finally, the researchers performed important steps towards the realization of strongly-correlated topological systems, which could exhibit even more complex behavior.
The scientific results obtained in TOPODY have led to the publication of 11 scientific articles and two pre-prints. The results have also been presented in many scietific workshops and conferences.
The research conducted in the TOPODY project has led to significant progress beyond the state of the art in several key areas:
(1) Development of Synthetic Dimensions: Previous work in cold atomic gases had only used very small synthetic dimensions. The TOPODY project's extension of synthetic dimensions to the large spin of dysprosium atoms opens up the possibility to simulate systems closer to the thermodynamic limit.
(2) Extensive Use of Light-Spin Interaction: The researchers extensively utilized the light-spin interaction based on the proximity to a narrow optical transition of dysprosium. This technique could serve as a foundation for various types of developments in cold atomic gas systems.
(3) Generation of Non-Classical Spin States: The light-spin interaction was used to generate highly non-classical spin states, which are relevant for quantum metrology applications.
(4) Realization of Complex Topological Systems: The researchers were able to realize topological systems with no equivalent in condensed matter systems or other platforms, demonstrating the flexibility and power of their approach.
(5) Realization of Quantum Systems in Higher Dimensions: The project culminated in the realization of quantum systems effectively evolving in dimensions above 3, pushing the boundaries of what is possible in the exploration of topological quantum matter.
(1) Development of Synthetic Dimensions: Previous work in cold atomic gases had only used very small synthetic dimensions. The TOPODY project's extension of synthetic dimensions to the large spin of dysprosium atoms opens up the possibility to simulate systems closer to the thermodynamic limit.
(2) Extensive Use of Light-Spin Interaction: The researchers extensively utilized the light-spin interaction based on the proximity to a narrow optical transition of dysprosium. This technique could serve as a foundation for various types of developments in cold atomic gas systems.
(3) Generation of Non-Classical Spin States: The light-spin interaction was used to generate highly non-classical spin states, which are relevant for quantum metrology applications.
(4) Realization of Complex Topological Systems: The researchers were able to realize topological systems with no equivalent in condensed matter systems or other platforms, demonstrating the flexibility and power of their approach.
(5) Realization of Quantum Systems in Higher Dimensions: The project culminated in the realization of quantum systems effectively evolving in dimensions above 3, pushing the boundaries of what is possible in the exploration of topological quantum matter.