TY - JOUR
T1 - Unsupervised Classification of Quantum Data
JF - Physical Review X
Y1 - 2019
A1 - Sentís, Gael
A1 - Monras, Alex
A1 - Muñoz-Tapia, Ramon
A1 - Calsamiglia, John
A1 - Bagan, Emilio
VL - 9
UR - https://link.aps.org/doi/10.1103/PhysRevX.9.041029http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevX.9.041029/fulltexthttps://link.aps.org/article/10.1103/PhysRevX.9.041029
JO - Phys. Rev. X
ER -
TY - JOUR
T1 - Duality Games and Operational Duality Relations
JF - Physical Review Letters
Y1 - 2018
A1 - Bagan, Emilio
A1 - Calsamiglia, John
A1 - Bergou, János A.
A1 - Hillery, Mark
VL - 120
UR - https://link.aps.org/doi/10.1103/PhysRevLett.120.050402http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.120.050402/fulltexthttps://link.aps.org/article/10.1103/PhysRevLett.120.050402
JO - Phys. Rev. Lett.
ER -
TY - JOUR
T1 - A generalized wave-particle duality relation for finite groups
JF - Journal of Physics A: Mathematical and Theoretical
Y1 - 2018
A1 - Bagan, Emilio
A1 - Calsamiglia, John
A1 - Bergou, János A
A1 - Hillery, Mark
VL - 51
JO - J. Phys. A: Math. Theor.
ER -
TY - JOUR
T1 - Discrimination Power of a Quantum Detector
JF - Physical Review Letters
Y1 - 2017
A1 - Hirche, Christoph
A1 - Hayashi, Masahito
A1 - Bagan, Emilio
A1 - Calsamiglia, John
VL - 118
UR - http://link.aps.org/doi/10.1103/PhysRevLett.118.160502http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.118.160502/fulltexthttp://link.aps.org/article/10.1103/PhysRevLett.118.160502
JO - Phys. Rev. Lett.
ER -
TY - JOUR
T1 - Quantum Change Point
JF - Physical Review Letters
Y1 - 2016
A1 - Sentís, Gael
A1 - Bagan, Emilio
A1 - Calsamiglia, John
A1 - Chiribella, Giulio
A1 - Muñoz-Tapia, Ramon
VL - 117
UR - http://link.aps.org/doi/10.1103/PhysRevLett.117.150502http://link.aps.org/article/10.1103/PhysRevLett.117.150502
JO - Phys. Rev. Lett.
ER -
TY - JOUR
T1 - Beating noise with abstention in state estimation
JF - New Journal of Physics
Y1 - 2012
A1 - Gendra, Bernat
A1 - Ronco-Bonvehi, Elio
A1 - Calsamiglia, John
A1 - Muñoz-Tapia, Ramon
A1 - Bagan, Emilio
VL - 14
UR - http://iopscience.iop.org/1367-2630/14/10/105015
ER -
TY - JOUR
T1 - Quantum learning without quantum memory
JF - Scientific Reports (Nature Publishing Group)
Y1 - 2012
A1 - Sentís, Gael
A1 - Calsamiglia, John
A1 - Muñoz-Tapia, Ramon
A1 - Bagan, Emilio
AB - A quantum learning machine for binary classification of qubit states that does not require quantum memory is introduced and shown to perform with the minimum error rate allowed by quantum mechanics for any size of the training set. This result is shown to be robust under (an arbitrary amount of) noise and under (statistical) variations in the composition of the training set, provided it is large enough. This machine can be used an arbitrary number of times without retraining. Its required classical memory grows only logarithmically with the number of training qubits, while its excess risk decreases as the inverse of this number, and twice as fast as the excess risk of an “estimate-and-discriminate” machine, which estimates the states of the training qubits and classifies the data qubit with a discrimination protocol tailored to the obtained estimates.
PB - Nature Publishing Group
VL - 2
UR - http://www.nature.com/srep/2012/121005/srep00708/full/srep00708.html
ER -
TY - JOUR
T1 - Estimation of quantum finite mixtures
JF - Physical Review A
Y1 - 2010
A1 - de Vicente, J. I.
A1 - Calsamiglia, John
A1 - Muñoz-Tapia, Ramon
A1 - Bagan, Emilio
AB - We consider the problem of determining the weights of a quantum ensemble. That is to say, given a quantum system that is in a set of possible known states according to an unknown probability law, we give strategies to estimate the individual probabilities, weights, or mixing proportions. Such strategies can be used to estimate the frequencies at which different independent signals are emitted by a source. They can also be used to estimate the weights of particular terms in a canonical decomposition of a quantum channel. The quality of these strategies is quantified by a covariance-type error matrix. According with this cost function, we give optimal strategies in both the single-shot and multiple-copy scenarios. The latter is also analyzed in the asymptotic limit of large number of copies. We give closed expressions of the error matrix for two-component quantum mixtures of qubit systems. The Fisher information plays an unusual role in the problem at hand, providing exact expressions of the minimum covariance matrix for any number of copies.
VL - 81
UR - http://link.aps.org/doi/10.1103/PhysRevA.81.012332
ER -
TY - JOUR
T1 - Recycling of qubits
JF - Physica Scripta
Y1 - 2010
A1 - P Rapcan
A1 - Calsamiglia, John
A1 - Muñoz-Tapia, Ramon
A1 - Bagan, Emilio
A1 - V Buzek
AB - We consider a finite number, N, of qubits that encode a pure single qubit state SU(2) covariantly. Given the N-qubit state has already been measured optimally to estimate the single-qubit state, we analyse the maximum information obtainable by a second, and subsequent observers ignorant of important details of the previous measurements. We quantify the information acquired by each observer as a function of N and of the number of independent observers that in succession have independently measured the same ensemble of qubits before him.
VL - T140
UR - http://iopscience.iop.org/1402-4896/2010/T140/014059?fromSearchPage=true
ER -