  We analyze the crosstalk error mechanism in measurement of two capacitively
coupled superconducting flux-biased phase qubits. The damped oscillations of
the superconducting phase after the measurement of the first qubit may
significantly excite the second qubit, leading to its measurement error. The
first qubit, which is highly excited after the measurement, is described
classically. The second qubit is treated both classically and
quantum-mechanically. The results of the analysis are used to find the upper
limit for the coupling capacitance (thus limiting the frequency of two-qubit
operations) for a given tolerable value of the measurement error probability.
