Summary form only given. The hydrogen atom played an illustrious role in the development of quantum mechanics and quantum electrodynamics. Hydrogen spectroscopy relentlessly advanced the frontiers of metrology and ultraprecise measurements. Hydrogen also helped launch the search for Bose-Einstein condensation in an atomic gas. Today, these paths are converging to a new focus: the physics of ultracold hydrogen.
Summary form only given. The hydrogen atom played an illustrious role in the development of quantum mechanics and quantum electrodynamics. Hydrogen spectroscopy relentlessly advanced the frontiers of metrology and ultraprecise measurements. Hydrogen also helped launch the search for Bose-Einstein condensation in an atomic gas. Today, these paths are converging to a new focus: the physics of ultracold hydrogen.
The realization of Bose-Einstein Condensation (BEC) in dilute gases of ultracold atoms has revolutionized quantum physics by offering an unprecedented platform to study quantum phenomena on macroscopic scales. Ultracold atomic systems, cooled to temperatures near absolute zero, exhibit collective behaviors governed by quantum statistics, coherence, and interactions. This article discusses the theoretical and experimental frameworks underpinning the formation of BECs, focusing on the trapping, cooling, and coherence properties of ultracold bosonic gases. Further, we delve into the role of quantum phase transitions, atom-atom interactions, and external field manipulation in controlling condensate dynamics. The implications of BECs extend into precision measurements, quantum simulation, and quantum computing, positioning them as a cornerstone in modern atomic and condensed matter physics.
We report observation of Bose-Einstein condensation (BEC) of a trapped, dilute gas of atomic hydrogen. The condensate and normal gas are studied by two-photon spectroscopy of the 1S- 2S transition. Interactions among the atoms produce a shift of the resonance frequency proportional to density. The condensate is clearly distinguished by its large frequency shift. The peak condensate density is $4.8\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{cm}}^{\ensuremath{-}3}$, corresponding to a condensate population of 109 atoms. The BEC transition occurs at about $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}50\ensuremath{\mu}\mathrm{K}$ and $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\ifmmode\times\else\texttimes\fi{}{10}^{14}{\mathrm{cm}}^{\ensuremath{-}3}$.
The field of ultracold atomic physics has developed rapidly during the last two decades, and currently encompasses a broad range of topics in physics, with a variety of important applications in topics ranging from quantum computing and simulation to quantum metrology, and can be used to probe fundamental many-body effects such as superconductivity and superfluidity. Beginning with the underlying and including the most cutting-edge experimental developments, this textbook covers essential topics such as Bose-Einstein condensation of alkali atoms, studies of BEC-BCS crossover in degenerate Fermi gas, synthetic gauge fields and Hubbard models, and many-body localization and dynamical gauge fields. Key physical concepts, such as symmetry and universality highlight the connections between different systems, and theory is developed with plain derivations supported by experimental results. This self-contained and modern text will be invaluable for researchers, graduate students and advanced undergraduates studying cold atom physics, from both a theoretical and experimental perspective.
The recent report of the observation of Bose-Einstein condensation in atomic Hydrogen, characterized by an anomalous density spectrum, is shown to be in agreement with the prediction of the existence of two condensates for temperatures lower than a well defined temperature (which for Hydrogen is $ 105~ \mu K $), based on the QED coherent interaction in a gas of ultracold atoms at a density n>n0(n0=(1/λ)3,λ being the wave-length of the e.m. modes resonantly coupled to the Hydrogen atoms)
Spin-polarized atomic hydrogen continues to be one of the most promising candidates for Bose condensation of an atomic system. In contrast to liquid helium, hydrogen is gaseous and therefore its density can be changed to vary its behavior from the weakly to the strongly interacting Bose gas. Until now, efforts to Bose condense hydrogen have been thwarted by recombination and relaxation phenomena. After a long introduction to the subject, two promising approaches to observe quantum degenerate behavior are discussed: the microwave trap and a two-dimensional gas of hydrogen. Introduction Since the stabilization of atomic hydrogen as a spin-polarized gas (H↓), reported in 1980 [1], there has been a continuous effort to observe Bose–Einstein condensation (BEC) or other effects of quantum degeneracy in this Bose gas. This challenge has not yet been realized due to the instability of H↓ towards recombination to H 2 or relaxation among hyperfine states as the conditions for BEC are approached. Although this difficulty is formidable, hydrogen presents a unique opportunity to study BEC and the related superfluidity, as it remains a gas to T = 0 [2]. By comparison, 4 He, the only experimentally observed boson fluid, is a strongly interacting superfluid Bose liquid, with little flexibility for varying its density. As a result of the gaseous nature of hydrogen, its density, n , can be varied over several orders of magnitude with the possibility of studying BEC and its relationship to superfluidity, ranging from the weakly to the strongly interacting boson gas.
The experimental observation of Bose-Einstein condensation in gas of rubidium atoms in 1995 had huge impact on the physics community with reports of a new state of matter making newspaper headlines all over the world. By comparison, it was in relative obscurity that Simo Jaakkola and his group at the University of Turku in Finland, in collaboration with researchers at the Kurchatov Institute in Moscow, recently observed the two-dimensional analogue of the effect (A I Safonov et al. 1998 Phys. Rev. Lett. 81 4545). Jaakkola observed two-dimensional Bose-Einstein condensation (2D BEG) in gas of specially prepared hydrogen atoms adsorbed on the surface of liquid helium. In Bose-Einstein condensation all the particles in system collapse into single quantum state that has many unusual and novel properties.