425 citations · 1.1k across the 32 of their papers we have counts for
13 papers · 1 filter
Secrecy content of two-qubit states
A. Acín, J. Bae, E. Bagan +3
We analyze the set of two-qubit states from which a secret key can be extracted by single-copy measurements plus classical processing of the outcomes. We introduce a key distillati…
Multiple copy 2-state discrimination with individual measurements
A Acin, E. Bagan, M. Baig +2
We address the problem of non-orthogonal two-state discrimination when multiple copies of the unknown state are available. We give the optimal strategy when only fixed individual m…
Quantum reverse-engineering and reference frame alignment without non-local correlations
E. Bagan, M. Baig, R. Munoz-Tapia
Estimation of unknown qubit elementary gates and alignment of reference frames are formally the same problem. Using quantum states made out of qubits, we show that the theoreti…
Optimal reconstruction of a pure qubit state with local measurements
E. Bagan, M. Baig, A. Monras +1
We analyse the reconstruction of an unknown pure qubit state. We derive the optimal guess that can be inferred from any set of measurements on N identical copies of the system with…
Collective vs local measurements in qubit mixed state estimation
E. Bagan, M. Baig, R. Munoz-Tapia +1
We discuss the problem of estimating a general (mixed) qubit state. We give the optimal guess that can be inferred from any given set of measurements. For collective measurements a…
Entanglement assisted alignment of reference frames using a dense covariant coding
E. Bagan, M. Baig, R. Munoz-Tapia
We present a procedure inspired by dense coding, which enables a highly efficient transmission of information of a continuous nature. The procedure requires the sender and the reci…
Minimal measurements of the gate fidelity of a qudit map
E. Bagan, M. Baig, R. Munoz-Tapia
We obtain a simple formula for the average gate fidelity of a linear map acting on qudits. It is given in terms of minimal sets of pure state preparations alone, which may be inter…
Optimal scheme for estimating a pure qubit state via local measurements
E. Bagan, M. Baig, R. Munoz-Tapia
We present the optimal scheme for estimating a pure qubit state by means of local measurements on N identical copies. We give explicit examples for low N. For large N, we show that…
Communicating a direction using spin states
E. Bagan, M. Baig, R. Munoz-Tapia
The communication of directions using quantum states is a useful laboratory test for some basic facts of quantum information. For a system of spin-1/2 particles there are different…
Aligning Reference Frames Using Quantum States
E. Bagan, M. Baig, R. Munoz-Tapia
We analyze the problem of sending, in a single transmission, the information required to specify an orthogonal trihedron or reference frame through a quantum channel made out of N…
Optimal encoding and decoding of a spin direction
E. Bagan, M. Baig, A. Brey +2
For a system of N spins 1/2 there are quantum states that can encode a direction in an intrinsic way. Information on this direction can later be decoded by means of a quantum measu…
Communication of Spin Directions with Product States and Finite Measurements
E. Bagan, M. Baig, R. Munoz-Tapia
Total spin eigenstates can be used to intrinsically encode a direction, which can later be decoded by means of a quantum measurement. We study the optimal strategy that can be adop…
Optimal strategies for sending information through a quantum channel
E. Bagan, M. Baig, A. Brey +2
Quantum states can be used to encode the information contained in a direction, i.e., in a unit vector. We present the best encoding procedure when the quantum state is made up of $…