2007/10/24 by D. M. Lucas, B. C. Keitch, Lucas, D. M. +13 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #Quantum Physics (quant-ph) #quant-ph
paper · pdf · doi:10.48550/arxiv.0710.4421
4 pages, 4 figures
arxiv created 2007/10/24 · arxiv updated 2009/12/01
We demonstrate long-lived coherence in internal hyperfine states of a single \Ca43 trapped-ion qubit [T2=1.2(2)\s], and in external motional states of a single \Ca40 trapped-ion qubit [T2'=0.18(4)\s], in the same apparatus. The motional decoherence rate is consistent with the heating rate, which was measured to be 3(1) quanta/sec. Long coherence times in the external motional states are essential for performing high-fidelity quantum logic gates between trapped-ion qubits. The internal-state T2 time that we observe in \Ca43, which has not previously been used as a trapped-ion qubit, is about one thousand times longer than that of physical qubits based on \Ca40 ions. Using a single spin-echo pulse to ``re-phase'' the internal state, we can detect no decoherence after 1\s, implying an effective coherence time T2\tiny SE \gtish 45\s. This compares with timescales in this trap for single-qubit operations of \ish 1\us, and for two-qubit operations of \ish 10\us.