Thesis and Dissertation Defenses
Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins
Presented by Leigh M. Norris
Spin squeezed states have applications in metrology and quantum information processing. While there has been significant progress in producing spin squeezed states and understanding their properties, most spin squeezing research to date has focused on ensembles of two-level systems or qubits. We explore squeezed state production in an ensemble of spin f>1/2 alkali atoms (qudits). The Faraday effect, which couples the collective spin of the atomic ensemble and the polarization modes of an optical field, can be used to mediate entangling interactions between the atoms that generate spin squeezing. This process can be enhanced with further control of the atomic qudits. Initial state preparation increases the collective squeezing through enhancement of resolvable quantum fluctuations, but comes at a price of increased decoherence. We find an optimal state preparation, achieving increased squeezing while remaining robust to decoherence. After the collective interaction, qudit control maps the generated entanglement to different pseudo-spin subspaces where it is metrologically useful, e.g., the clock transition or the stretched state for magnetometry. In the latter case, additional internal control can be used to squeeze the individual atoms, further enhancing the total squeezing in a multiplicative manner. These considerations highlight the unique capabilities of our platform: we are able to transfer coherences and correlations between subspaces and integrate control tools to explore a wider variety of nonclassical states, with ultimate application in sensors or other quantum information processors.
2:00 pm, Monday, July 14, 2014
PAIS-2540, PAIS
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