Student Support: Spin Decoherence Measurements for Solid State Qubits
Final rept. 1 Jun 2002-31 Oct 2005
YALE UNIV NEW HAVEN CT
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This project supported Mr. Dale Li with a Quantum Computation Graduate Research QuaCGR Fellowship. Dale played a key role as the most senior student in our group, during our work on the research grant DAAD19-01-1-0507 Spin Decoherence Measurements for Solid State Qubits . That projects initial goal was to measure decoherence times for solid-state qubits. We unexpectedly found a clear discrepancy between two different standard measurements of T2 . Specifically, well-known multiple Pi-pulse spin echo experiments had the ability either to freeze out or to accelerate the signal decay expected due to the spin-spin dipolar coupling, reminiscent of the quantum Zeno effect. Dale implemented a series of careful experiments that identified the essential spin Hamiltonian. In addition, he worked on the theoretical description using both analytical techniques and numerical simulation. Dale s work revealed a novel many-body effect, arising from the tiny spin-spin interactions acting during strong, but finite, control pulses. Similar effects should be expected for most physical qubits not just spins driven by bang-bang control sequences, or other pulse control sequences.
- Quantum Theory and Relativity
- Solid State Physics