Fig. 2: Device and optimized quantum circuit.
From: Variational preparation of finite-temperature states on a quantum computer
a Optical image of the transmon processor was used in this experiment, with false color highlighting the four transmons employed and the dedicated bus resonators providing their nearest-neighbor coupling. Scale bar corresponds to 1 mm. b Optimized circuit equivalent to that in Fig. 1(b) and conforming to the native gate set in our architecture. All variational parameters are mapped onto rotation axes and angles of single-qubit gates. Tomographic pre-rotations R1–R4 are added to reconstruct the terms in the cost function \({{{\mathcal{C}}}}\) and to perform two-qubit state tomography of each system following optimization.
