Student Support: Spin Decoherence Measurements for Solid State Qubits
Author | : |
Publisher | : |
Total Pages | : 15 |
Release | : 2005 |
ISBN-10 | : OCLC:227911196 |
ISBN-13 | : |
Rating | : 4/5 (96 Downloads) |
Book excerpt: 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 project's 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.