Publications (11)
Encoding many qubits in a rotor
Amir Kalev, Philippe Raynal, Jun Suzuki +1
We propose a scheme for encoding many qubits in a single rotor, that is, a continuous and periodic degree of freedom. A key feature of this scheme is its ability to manipulate and…
Mutually unbiased bases in dimension six: The four most distant bases
Philippe Raynal, Xin Lü, Berthold-Georg Englert
We consider the average distance between four bases in dimension six. The distance between two orthonormal bases vanishes when the bases are the same, and the distance reaches its…
Simple derivation of the Weyl and Dirac quantum cellular automata
Philippe Raynal
We consider quantum cellular automata on a body-centred cubic lattice and provide a simple derivation of the only two homogenous, local, isotropic, and unitary two-dimensional auto…
Reduction Theorems for Optimal Unambiguous State Discrimination of Density Matrices
Philippe Raynal, Norbert Lütkenhaus, Steven J. van Enk
We present reduction theorems for the problem of optimal unambiguous state discrimination (USD) of two general density matrices. We show that this problem can be reduced to that of…
Implementing Non-Projective Measurements via Linear Optics: an Approach Based on Optimal Quantum State Discrimination
Peter van Loock, Kae Nemoto, William J. Munro +2
We discuss the problem of implementing generalized measurements (POVMs) with linear optics, either based upon a static linear array or including conditional dynamics. In our approa…
Optimal Lewenstein-Sanpera decomposition of two-qubit states using Semidefinite Programming
Guo Chuan Thiang, Philippe Raynal, Berthold-Georg Englert
We use the language of semidefinite programming and duality to derive necessary and sufficient conditions for the optimal Lewenstein-Sanpera Decomposition (LSD) of 2-qubit states.…
Unambiguous State Discrimination of two density matrices in Quantum Information Theory
Philippe Raynal
In this thesis we study the problem of unambiguously discriminating two mixed quantum states. We first present reduction theorems for optimal unambiguous discrimination of two gene…
Optimal Unambiguous State Discrimination of two density matrices and its link with the Fidelity
Philippe Raynal, Norbert Lütkenhaus
Recently the problem of Unambiguous State Discrimination (USD) of mixed quantum states has attracted much attention. So far, bounds on the optimum success probability have been der…
Optimal unambiguous state discrimination of two density matrices: A second class of exact solutions
Philippe Raynal, Norbert Lütkenhaus
We consider the Unambiguous State Discrimination (USD) of two mixed quantum states. We study the rank and the spectrum of the elements of an optimal USD measurement. This naturally…
Mutually unbiased bases for the rotor degree of freedom
Xin Lü, Philippe Raynal, Berthold-Georg Englert
We consider the existence of a continuous set of mutually unbiased bases for the continuous and periodic degree of freedom that describes motion on a circle (rotor degree of freedo…
Optimality of entropic uncertainty relations
Kais Abdelkhalek, René Schwonnek, Hans Maassen +5
The entropic uncertainty relation proven by Maassen and Uffink for arbitrary pairs of two observables is known to be non-optimal. Here, we call an uncertainty relation optimal, if…