8 papers · 1 filter
Counterexamples to the fractional coloring conjecture for triply efficient shadow tomography
Jędrzej Stempin, Santiago Llorens, Felix Huber
Fractional graph colorings are useful for the Shadow tomography of Pauli observables. In practice, it is desirable that any experimentally interesting set of Pauli operators has a…
Combining moment matrices, symmetric extension, and Lovász theta: is entangled
Jȩdrzej Stempin, Gerard Anglès Munné, Santiago Llorens +1
We solve an open problem in entanglement theory posed by Yu et al., {\it Nature Communications 12, 1012 (2021)}. The problem is to show, via an entanglement witness, that the -…
Exact identification of unknown unitary processes
Santiago Llorens, Arnau Diebra, Michal Sedlák +1
The accurate identification of faulty hardware is a fundamental requirement for reliable quantum information processing. We address this problem in a quantum setting, where a serie…
Quantum Advantage in Identifying the Parity of Permutations with Certainty
Arnau Diebra, Santiago Llorens, David González-Lociga +4
We establish a sharp quantum advantage in determining the parity (even/odd) of an unknown permutation applied to any number of particles. Classically, this is impossible…
Quantum state exclusion for group-generated ensembles of pure states
Arnau Diebra, Santiago Llorens, Emili Bagan +2
Quantum state exclusion is the task of determining which states from a given set a system was not prepared in. We provide a complete solution to optimal quantum state exclusion for…
Quantum Edge Detection
Santiago Llorens, Walther González, Gael Sentís +3
This paper introduces quantum edge detection, aimed at locating boundaries of quantum domains where all particles share the same pure state. Focusing on the 1D scenario of a string…