Abstract: The present disclosure may include methods, devices, and systems for constructing a routed circuit to allocate information qubits. The routed circuit may comprise at least one two-qubit gate and zero or more one-qubit gates on a quantum chip structure represented by a graph comprising vertices and edges.

Abstract: A method is disclosed for estimating an expectation value of an observable of at least one target Hamiltonian using a base Hamiltonian, the method comprising obtaining an indication of a base Hamiltonian and an indication of an observable; setting a sampling device using the base Hamiltonian; obtaining from the sampling device a plurality of samples from a probability distribution defined by the base Hamiltonian; for each target Hamiltonian of a list of at least one target Hamiltonian: estimating an expectation value of the observable corresponding to the target Hamiltonian using the obtained plurality of samples from the probability distribution defined by the base Hamiltonian, the estimating comprising: computing a sample estimate of a ratio of partition functions of the target Hamiltonian and the base Hamiltonian, computing an unnormalized estimate for an expectation value of the observable with respect to the probability distribution defined by the target Hamiltonian, computing an estimate for an expectat