Efficient pulsed gates for an oscillator stabilized Josephson qubit IBM Watson In arXiv 0709.1478 and New J. Phys. 10 033027 (2008), Koch, DiVincenzo, Brito and Steffen derive operational specifications for high-fidelity one and two-qubit pulsed gates for a superconducting flux qubit, calculating the Hamiltonian with tunable interaction from initialization to readout.
"The quantitative fact that the values of gate inﬁdelity are at the 1% level – and below – is the major result of this paper."
So, can a "debugged" IBM qubit be used soon for universal quantum computation?
"The short answer is, in our opinion, ultimately yes."
"The answer would certainly be no if the noise threshold for fault-tolerant quantum computation were in the neighborhood of the oft-quoted value of 10−5. It is not inconceivable for the experiment to get to these values someday, since we ﬁnd that the inﬁdelities decrease much faster than linearly with the assumed noise levels."
"To get to 10−5, we would need to get to the very daunting levels of 100nΦ0 at 1Hz for the 1/f noise amplitudes and 100 f s for timing accuracies; there is optimism that both of these numbers are ultimately attainable. Fortunately, while 10−5 was the threshold as it was understood ten years ago, much recent work shows that with good designs, much higher thresholds are possible. According to Terhal and Burkard – 1% is, in fact, on the high end of the noise levels for which fault tolerance may be possible."