Zobrazeno 1 - 10
of 216
pro vyhledávání: '"Siudzińska, A."'
Autor:
Siudzińska, Katarzyna
We use operators from generalized equiangular measurements to construct positive maps. Their positivity follows from the inequality for indices of coincidence corresponding to few equiangular tight frames. These maps give rise to entanglement witness
Externí odkaz:
http://arxiv.org/abs/2411.07065
We explore a notion of decomposably divisible (D-divisible) quantum evolution families, recently introduced in J. Phys. A: Math. Theor. 56, 485202 (2023). Both necessary and sufficient conditions are presented for highly-symmetric qubit and qudit dyn
Externí odkaz:
http://arxiv.org/abs/2411.01712
Autor:
Rutkowski, Adam, Siudzińska, Katarzyna
This paper explores geometric aspects of the inverse Choi-Jamio{\l}kowski isomorphism. It focuses on qubit channels corresponding to two-qubit circulant states that satisfy Bell's nonlocality condition. The main part is devoted to a characterization
Externí odkaz:
http://arxiv.org/abs/2407.16035
Autor:
Siudzińska, Katarzyna
Publikováno v:
J. Phys. A: Math. Theor. 57 335302 (2024)
Informationally overcomplete measurements find important applications in quantum tomography and quantum state estimation. The most popular are maximal sets of mutually unbiased bases, for which trace relations between measurement operators are well k
Externí odkaz:
http://arxiv.org/abs/2405.00560
Autor:
Siudzińska, Katarzyna
Publikováno v:
J. Phys. A: Math. Theor. 57 355301 (2024)
We introduce a generalization of symmetric measurements to collections of unequinumerous positive, operator-valued measures (POVMs). For informationally complete sets, we propose construction methods from orthonormal Hermitian operator bases. The cor
Externí odkaz:
http://arxiv.org/abs/2404.02034
Autor:
Siudzińska, Katarzyna
Publikováno v:
Phys. Rev. A 110, 012440 (2024)
We use symmetric measurement operators to construct quantum channels that provide a further generalization of generalized Pauli channels. The resulting maps are bistochastic but in general no longer mixed unitary. We analyze their important propertie
Externí odkaz:
http://arxiv.org/abs/2402.04415
Autor:
Siudzińska, Katarzyna
We analyze the evolution of Holevo and entanglement-assisted classical capacities for a special class of phase-covariant channels. In particular, we show that these capacities can be improved by changing the stationary state of the channel, which is
Externí odkaz:
http://arxiv.org/abs/2302.11519
Publikováno v:
J. Phys. A: Math. Theor. 56, 205301 (2023)
We analyze quantum communication properties of phase-covariant channels depending on their degree of non-unitality. In particular, we derive analytical formulas for minimal and maximal channel fidelity on pure states and maximal output purity. Next,
Externí odkaz:
http://arxiv.org/abs/2212.04876
Autor:
Siudzińska, Katarzyna
We analyze the geometry on the space of non-unital phase-covariant qubit maps. Using the corresponding Choi-Jamio{\l}kowski states, we derive the Hilbert-Schmidt line and volume elements using the channel eigenvalues together with the parameter that
Externí odkaz:
http://arxiv.org/abs/2210.17448
Autor:
Siudzińska, Katarzyna
We analyze convex combinations of non-unital qubit maps that are phase-covariant. In particular, we consider the behavior of maps that combine amplitude damping, inverse amplitude damping, and pure dephasing. We show that mixing non-unital channels c
Externí odkaz:
http://arxiv.org/abs/2206.10742