current bias leads by an auxiliary junction $J2$ (with $I_{02}$ and $C_2$) and geometrical inductances $L_1$ and $L_2$. The device is controlled with a current bias $I_b$ and a flux current $I_f$ which generates flux $\Phi_a$ through mutual inductance $M$. Transitions can be induced by a microwave current [$I_{r\!f}$]{}, which is coupled to $J1$ via [$C_{r\!f}$]{}. (b) When biased appropriately, the dynamics of the phase difference $\gamma_1$ across the qubit junction are analogous to those of a ball in a one-dimensional tilted washboard potential $U$. The metastable state [$\left| n \right>$]{} differs in energy from [$\left| m \right>$]{} by $\hbar {\ensuremath{\omega_{n m}}}$ and tunnels to the voltage state with a rate [$\Gamma_{n}$]{}. (c) The photograph shows a Nb/AlO$_\text{x}$/Nb device. Not seen is an identical SQUID coupled to this device intended for two-qubit experiments; the second SQUID was kept unbiased throughout the course of this work.](Devicev3.eps){width="3.0in"}

Figure \[FDevice\](a) shows the circuit schematic for our dc SQUID phase qubit.[@Palomaki06a] The qubit junction $J1$ (with critical current $I_{01}$ and capacitance $C_1$) is shown on the left. It is isolated from the current bias source $I_b$ by geometrical inductances $L_1$ and $L_2$ and the second junction $J2$ (with $I_{02}$ and $C_2$). In order to 