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Identifier 000436573
Title Spin noise correlations in multispecies hot atomic vapors
Alternative Title Συσχετίσεις θορύβου σπιν σε πολυατομικά θερμά ατομικά αέρια
Author Μουλουδάκης, Κωνσταντίνος Β
Thesis advisor Κομίνης, Ιωάννης
Abstract Spin-exchange collisions in alkali-metal vapors underlie several fundamental and applied investigations such as nuclear structure studies and tests of fundamental symmetries, ultrasensitive atomic magnetometers, magnetic resonance, and biomagnetic imaging. The effect of spin-exchange collisions on the atomic system is very rich and it can vary depending on the conditions: it can cause decoherence and produce spin noise, or it can transfer spin-polarization and coherences without contributing to spin relaxation. Recently, with the development of quantum measurements and quantum technology in general, spin-exchange collisions have attracted a lot of interest as a resource for quantum metrology and as a potential source of quantum noise. We have performed a precision experiment regarding spin-noise correlations in multispecies hot alkali vapors. In particular, we observe non-zero spin-noise correlations and coherence transfer effects in equilibrium between overlapping 133Cs and 87Rb spin ensembles, having different gyromagnetic ratios. Both observations stem from the spontaneous and incessant spin-exchange collisions that tend to couple the two atomic species through the coherent exchange of spin-polarization. We investigate the behaviour of the spontaneous spin-noise correlations both in a strong coupling regime at low magnetic fields where the spin-exchange rate is larger than the difference of the Larmor frequencies and in a weak coupling regime, at higher fields, where the fast Larmor precession tends to rapidly contract the formatted correlations. On theoretical grounds, we develop a quantum-trajectory picture of spin-exchange collisions, consistent with their long-standing ensemble description using density matrices. We then use quantum trajectories to reveal the nature of spin-noise correlations that spontaneously build up in multispecies atomic vapors, frequently utilized in the most sensitive spin measurements. Finally, we show that spin-exchange collisions in hot alkali vapors naturally produce strong bipartite entanglement, which we explicitly quantify using the tools of quantum information science. This entanglement is shown to have a lifetime at least as long as the spin-exchange relaxation time, and to directly affect measurable spin noise observables. We present a formal theoretical demonstration that a hot and dense atomic vapor can support longlived bipartite and possibly higher-order entanglement. Deeper understanding of spin-noise exchange in dual-species hot alkali vapors may advance the operation of atomic devices like for example atomic magnetometers and atomic gradiometers and it may also contribute to the development of new quantum protocols and devices.
Language English
Subject Alkali vapors
Atomic magnetometry
Atomic physics
Dual-species
Entanglement in spin exchange collisions
Precision measurements
Quantum metrology
Quantum physics
Quantum sensing
Quantum trajectories
Spin measurement
Αλκαλικά αέρια
Ατομική Μαγνητομετρία
Ατομική φυσική
Θόρυβος σπιν
Κβαντικές τροχές
Κβαντική μέτρηση
Κβαντική μετρολογία
Κβαντική φυσική
Μετρήσεις ακριβείας
Μετρήσεις σπιν
Σύμπλεξη στις συγκρούσεις ανταλλαγής σπιν
Issue date 2021-02-08
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/b/c/c/metadata-dlib-1610710723-689220-18581.tkl Bookmark and Share
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