Nearly Optimal Measurement Scheduling for Partial Tomography of Quantum States

Many applications of quantum simulation require one to prepare and then characterize quantum states by efficiently estimating k-body reduced density matrices (k-RDMs), from which observables of interest may be obtained. For instance, the fermionic 2-RDM contains the energy, charge density, and energy gradients of an electronic system, while...

Calculating energy derivatives for quantum chemistry on a quantum computer

Modeling chemical reactions and complicated molecular systems has been proposed as the“killer application”of a future quantumcomputer. Accurate calculations of derivatives of molecular eigenenergies are essential toward this end, allowing for geometryoptimization, transition state searches, predictions of the response to an applied electric or...

Experimental error mitigation via symmetry verification in a variational quantum eigensolver

Variational quantum eigensolvers offer a small-scale testbed to demonstrate the performance of error mitigation techniques with low experimental overhead. We present successful error mitigation by applying the recently proposed symmetry verification technique to the experimental estimation of the ground-state energy and ground state of the...

Low-cost error mitigation by symmetry verification

We investigate the performance of error mitigation via measurement of conserved symmetries on near-term devices. We present two protocols to measure conserved symmetries during the bulk of an experiment, and develop a third, zero-cost, post-processing protocol which is equivalent to a variant of the quantum subspace expansion. We develop...