Dysprosium Atoms Gain Laser Control with UV Light

Optically populating the first excited state in dysprosium is now achievable in cold atom experiments. A pathway to access this state using ultraviolet ground state transitions has been realised, achieving decay strengths comparable to the strongest transitions in dipolar atoms. Key to this is the investigation of transitions around 4134cm−1, offering a more accessible method than previously available wavelengths exceeding 1800nm. Kevin S. H. Ng of The University of Stuttgart and colleagues have found a method to excite dysprosium atoms using ultraviolet light, potentially simplifying quantum experiments.

The research reveals that certain ultraviolet transitions are as effective as those using longer wavelengths for stimulating atomic change, offering a more practical approach to atom control. Accessing this excited state with ultraviolet light may enable improvements in atomic clocks, high-resolution imaging and investigations into the fundamental properties of matter. Kevin S. H. Ng and colleagues have unlocked a pathway to manipulate dysprosium atoms, a key step towards advancements in quantum technology. Lanthanides, possessing large magnetic moments due to their open inner-shell electronic structure, present a rich landscape of transitions suitable for laser cooling, trapping, and coherent control. However, the exploitation of ultraviolet (UV) transitions below 400nm has been historically limited in dipolar atom experiments, creating a significant gap in experimental capabilities. This work addresses this limitation by systematically investigating multiple UV ground state transitions in dysprosium, a particularly promising lanthanide for quantum applications.

Until now, exciting these atoms to the first excited state proved difficult using standard methods. Ultraviolet light can efficiently drive transitions to this state, with strengths comparable to those achieved with previously used, longer wavelengths. This is akin to using a highly sensitive method for detecting faint signals. Understanding these transitions is vital for building more precise atomic clocks, improving high-resolution imaging techniques, and probing the fundamental structure of matter. Specifically, Kevin S. H. Ng and colleagues measured isotope shifts, slight variations in atomic energy levels based on neutron count. Isotope shifts provide crucial information about the nuclear structure and the interactions between the nucleus and the electrons, offering a sensitive probe of fundamental physics. The ability to accurately measure these shifts is paramount for precise spectroscopic studies and the development of advanced quantum technologies.

Ultraviolet transitions enable high-precision spectroscopy and manipulation of dysprosium atoms

Decay strengths to the first excited state in dysprosium now reach 81×10⁶ s⁻¹, comparable to the strongest transitions in dipolar atoms. This represents a sharp increase from previously accessible methods limited to wavelengths exceeding 1800nm. Unlocking access to this ultralong-lived, low-lying first excited state, previously elusive in cold atom experiments, expands the set of tools for manipulating lanthanide atoms. Two-dimensional shelving spectroscopy, a technique enhancing detection sensitivity, proved instrumental in measuring isotope shifts and hyperfine coefficients with unprecedented precision, effectively isolating faint signals akin to discerning a quiet whisper amidst noise. Shelving spectroscopy works by selectively exciting atoms to a long-lived excited state, effectively removing them from the detection pathway for unwanted transitions, thereby enhancing the signal-to-noise ratio. This technique is particularly valuable when studying weak transitions or resolving closely spaced energy levels.

Dr. Benjamin Bloom and colleagues identified these ultraviolet ground state transitions, offering a pathway towards creating more precise optical clocks, improving high-resolution imaging, and probing fundamental physics beyond the standard model. Spanning wavelengths from 359.0nm to 372.5nm, the newly measured transitions exhibit large decay rates to the ultralong-lived first excited state. Shelving spectroscopy confirmed five transitions decaying via a single channel to this state. The ultralong-lived nature of the first excited state is crucial for several applications. Its extended lifetime allows for more precise measurements of atomic properties and facilitates the implementation of coherent control schemes, where the quantum state of the atom is manipulated with high fidelity. The identification of a single decay channel simplifies the analysis and interpretation of experimental data.

The relative decay ratio to the first excited state and ground state varied between approximately 1000:1 and 0.3:1 across the studied transitions, enhancing signal amplification by a factor of around 180. Detailed modelling of dysprosium’s energy levels will be enabled by this precise measurement of isotope shifts and hyperfine coefficients, vital for understanding the electronic structure of these transitions. Hyperfine coefficients, which describe the interaction between the electron and the nuclear spin, are essential parameters for understanding the atomic structure and for controlling the atom’s quantum state. Initial scepticism surrounding the practical application of ultraviolet transitions in lanthanide experiments has been overcome, as these findings demonstrate a viable pathway for enhanced control and manipulation of these atoms. The challenges associated with generating and controlling UV light, coupled with the relatively low absorption cross-sections of lanthanides at these wavelengths, previously hindered the development of UV-based experiments. This work demonstrates that these challenges can be overcome with careful experimental design and optimisation.

Dysprosium’s strong decay strengths validate the use of UV light for accessing previously untapped quantum states, opening avenues for improved optical clocks, enhanced quantum gas microscopy, and probing fundamental physics; further investigation into analogous transitions within other magnetic atoms will likely broaden these advancements. Quantum gas microscopy, a technique allowing the observation of individual atoms in a cold atomic gas, benefits from the ability to manipulate atoms with high precision. The use of UV transitions could enable the creation of novel quantum states and the exploration of new quantum phenomena. The exploration of similar transitions in other lanthanides, such as holmium or thulium, could lead to the development of even more powerful quantum technologies and a deeper understanding of the fundamental laws of nature. The potential for extending these findings to other magnetic atoms suggests a broader impact on the field of quantum science and technology.

The research successfully demonstrated strong decay strengths in ultraviolet transitions within dysprosium, overcoming previous limitations in utilising these wavelengths for lanthanide experiments. This finding means researchers now have a viable method for better control and manipulation of these atoms, potentially improving optical clocks and high-resolution imaging with quantum gas microscopy. Detailed measurements of isotope shifts and hyperfine coefficients provide crucial information about the electronic structure of these transitions, which also exists in other magnetic atoms. The authors suggest further investigation into these analogous transitions could broaden these advancements across the field.