Figure 2

(a) Parameterized quantum circuit ansatz \({|\psi (\boldsymbol{\theta })\rangle}\) and (b) connectivity of the ibmq_casablanca quantum processor used for the 5-qubit VQE, VarQITE and F-VQE results. Each \(R_{y}\) in (a) is a single-qubit rotation gate rotating the qubit around the Y axis by an individual angle θ per gate, \(R_{y}=R_{y}(\theta )=\exp (-i\theta Y/2)\). Gates in the dashed box are repeated p times, where p is the number of layers. In (b) each circle is a physical qubit and lines indicate their physical connectivity