For an isolated generic quantum system out of equilibrium, the long time average observables is given by diagonal ensemble, i.e. mixed state with same probability for energy eigenstates as initial but without coherences between different energies. In this work we present a method to approximate ensemble using tensor networks. Instead simulating real evolution, adapt filtering scheme introduced ...

We tackle the problem of estimating spatial distribution mobile phones from Mobile Network Operator (MNO) data, namely Call Detail Record (CDR) or signalling data. The process transforming MNO data to a density map requires geolocating radio cells determine their footprint. Traditional geolocation solutions rely on Voronoi tes sellations and approximate cell footprints by mutually disjoint regi...

We develop the gapped-filtering method, whereby a short Chebyshev expansion accurately represents density-matrix operator. The method optimizes coefficients to give correct density matrix at all energies except within gapped region where there are no eigenstates. Gapped filtering reduces number of required terms in compared traditional methods, as long one knows or can determine efficiently HOM...

A quantum measurement is logically reversible if the premeasurement density operator of the measured system can be calculated from the postmeasurement density operator and from the outcome of the measurement. This paper analyzes why many quantum measurements are logically irreversible, shows how to make them logically reversible, and discusses reversing measurement that returns the postmeasurem...

We develop priors for Bayes estimation of quantum states that provide minimax state estimation. The relative entropy from the true density operator to a predictive density operator is adopted as a loss function. The proposed prior maximizes the conditional Holevo mutual information, and it is a quantum version of the latent information prior in classical statistics. For one qubit system, we pro...

We examine the relationship between the decoherence of quantummechanical histories of a closed system (as discussed by Gell-Mann and Hartle) and environmentally-induced diagonalization of the density operator for an open system. We study a definition of decoherence which incorporates both of these ideas, and show that it leads to a consistent probabilistic interpretation of the reduced density ...