542 citations · 2.8k across the 71 of their papers we have counts for
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Separable Measurement Estimation of Density Matrices and its Fidelity Gap with Collective Protocols
E. Bagan, M. A. Ballester, R. D. Gill +2
We show that there exists a gap between the performance of separable and collective measurements in qubit mixed-state estimation that persists in the large sample limit. We charact…
Anti-Screening by Quarks and the Structure of the Inter-Quark Potential
E. Bagan, M. Lavelle, D. McMullan
The inter-quark potential is dominated by anti-screening effects which underly asymptotic freedom. We calculate the order g^6 anti-screening contribution from light fermions and de…
Optimal full estimation of qubit mixed states
E. Bagan, M. A. Ballester, R. D. Gill +2
We obtain the optimal scheme for estimating unknown qubit mixed states when an arbitrary number N of identically prepared copies is available. We discuss the case of states in the…
Purity estimation with separable measurements
E. Bagan, M. A. Ballester, R. Munoz-Tapia +1
Given a large number N of copies of a qubit state of which we wish to estimate its purity, we prove that separable-measurement protocols can be as efficient as the optimal joint-me…
A Quantum Field Theory Twist to Photon Angular Momentum
G. F. Calvo, A. Picon, E. Bagan
A quantum field theory approach is put forward to generalize the concept of classical spatial light beams carrying orbital angular momentum to the single-photon level. This quantiz…
Relative states, quantum axes and quantum references
E. Bagan, S. Iblisdir, R. Munoz-Tapia
We address the problem of measuring the relative angle between two "quantum axes" made out of N1 and N2 spins. Closed forms of our fidelity-like figure of merit are obtained for an…