W E L C O M E | learn more |
Research Center for Quantum Information
Institute of Physics, Slovak Academy of Sciences
Dúbravská cesta 9, 84511 Bratislava, Slovakia
Tel: (+421 +2) 20910701
Fax: (+421 +2) 5477-6085
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N E W S | old news |
  20.05.2019 Publication
Divisibility of qubit channels and dynamical maps
The concept of divisibility of dynamical maps is used to introduce an analogous concept for quantum channels by analyzing the simulability of channels by means of dynamical maps. In particular, this is addressed for Lindblad divisible, completely positive divisible and positive divisible dynamical maps. The corresponding L-divisible, CP-divisible and P-divisible subsets of channels are characterized (exploiting the results by Wolf et al. and visualized for the case of qubit channels. We discuss the general inclusions among divisibility sets and show several equivalences for qubit channels. To this end we study the conditions of L-divisibility for finite dimensional channels, especially the cases with negative eigenvalues, extending and completing the known results. Furthermore we show that transitions between every two of the defined divisibility sets are allowed. We explore particular examples of dynamical maps to compare these concepts. Finally, we show that every divisible but not infinitesimal divisible qubit channel (in positive maps) is entanglement-breaking, and open the question if something similar occurs for higher dimensions.
by David Davalos, Mario Ziman, and Carlos Pineda
Quantum 3, 144 (2019) | +++ |
HiPhoP (Quantera), MAXAP (VEGA 2/0173/17), QETWORK (APVV-14-0878), GACR GA16-22211S
  03.05.2019 Publication
Optimal Probabilistic Storage and Retrieval of Unitary Channels
We address the question of quantum memory storage for quantum dynamics. In particular, we design an optimal protocol for N -> 1 probabilistic storage and retrieval of unitary channels on D-dimensional quantum systems. If we access the unknown unitary gate only N times, the optimal success probability of perfect single-use retrieval is N/(N−1+d2). The derived size of the memory system exponentially improves the known upper bound on the size of the program register needed for probabilistic programmable quantum processors. Our results are closely related to probabilistic perfect alignment of reference frames and probabilistic port-based teleportation.
by Michal Sedlák, Alessandro Bisio, and Mário Ziman
Phys. Rev. Lett. 122, 170502 (2019) | +++ |
HiPhoP (Quantera), MAXAP (VEGA 2/0173/17), QETWORK (APVV-14-0878), GACR GA16-22211S
  03.06.2019 Conference
CEQIP 2019
We are happy to announce that 16th CEQIP workshop will be held in June (3-6) and this year we will explore a completely new venue - kings town Skalica (Vitriol). We expect the registration and the submission will be open in February and closed in mid March. Looking forward to see you there.
S E M I N A R S | more |
14/08 11:00
Harry Miller (Exeter)
Work fluctuations in slow processes: quantum signatures and optimal control
V I S I T O R S | history |

12.06-16.08 Harry Miller
(University of Exeter, Exeter, United Kingdom)