O L D   N E W S
: 2017 : 2016 : 2015 : 2014 : 2013 : 2012 : 2011 : 2010 : 2009 : 2008 : 2007 :
  14.09.2017 Research publication
Divisibility of quantum dynamical maps and collision models
The divisibility of dynamical maps is visualized by trajectories in the parameter space and analyzed within the framework of collision models. We introduce ultimate completely positive (CP) divisible processes, which lose CP divisibility under infinitesimal perturbations, and characterize Pauli dynamical semigroups exhibiting such a property. We construct collision models with factorized environment particles, which realize additivity and multiplicativity of generators of CP divisible maps. A mixture of dynamical maps is obtained with the help of correlated environment. The mixture of ultimate CP divisible processes is shown to result in a class of eternal CP indivisible evolutions. We explicitly find collision models leading to weakly and essentially non-Markovian Pauli dynamical maps.
by S. N. Filippov, J. Piilo, S. Maniscalco, and M. Ziman
Phys. Rev. A 96, 032111 (2017) |+++|
APVV-14-0878 (QETWORK), VEGA 2/0173/17 (MAXAP), GACR GA16-22211S
  13.09.2017 Research publication
Finding paths with quantum walks or quantum walking through a maze
We show that it is possible to use a quantum walk to find a path from one marked vertex to another. In the specific case of M stars connected in a chain, one can find the path from the first star to the last one in O(M√N) steps, where N is the number of spokes of each star. First we provide an analytical result showing that by starting in a phase-modulated highly superposed initial state we can find the path in O(M√N logM) steps. Next, we improve this efficiency by showing that the recovery of the path can also be performed by a series of successive searches when we start at the last known position and search for the next connection in O(√N) steps leading to the overall efficiency of O(M√N). For this result we use the analytical solution that can be obtained for a ring of stars of double the length of the chain.
by Daniel Reitzner, Mark Hillery, and Daniel Koch
Phys. Rev. A 96, 032323 (2017) |+++|
SASPRO, APVV-14-0878 (QETWORK), VEGA 2/0151/15 (QWIN)
  12.07.2017 popularisation
Vedci po prvý raz teleportovali fotón zo Zeme do vesmíru. Presunuli len informáciu, nie hmotu ako v Star Treku
Expert opinion of Daniel Nagaj for Dennik N in newspapers article. :: Ξ Dennik N Ξ ::
  31.05.2017 workshop
Central European Quantum Information Processing 2017
CEQIP workshop is traditionally focused on current challenges and paradigms of mathematical and computational aspects of emerging quantum technologies. Thanks all for coming and looking forward to see you next year. :: CEQIP website ::
  11.04.2017 seminar
In connection with the preparation of European Commission project "Quantum Flagship" the Presidum of Slovak Academy of Sciences is organizing an informal seminar aiming to introduce this project for Slovak researchers, to formulate our national priorities within the area of quantum technologies and to outline Slovak-wide supporting innitiative in the area of quantum technologies.

11:00 – 11:10 E. Majková (Presidum SAS): Opening
11:10 – 12:00 V. Bužek (Institute of Physics SAS, Bratislava): Introducing Quantum Flagship
Predstavenie výskumných skupín v oblasti kvantových technológií
12:00 – 12:20 M. Grajcar (Comenius University and Institute of Physics SAS Bratislava)
12:20 – 12:40 P. Samuely (Institute of Experimental Physics SAS, Košice)
12:40 – 13:40 obedňajšia prestávka
13:40 – 14:00 V. Cambel (Electrotechnical Institute SAS, Bratislava)
14:00 – 14:20 M. Ziman (Institute of Physics SAS, Bratislava)
14:20 – 15:50 discussion - National Project QUTE SLOVAKIA
15:50 – 16:00 Closing
Date: 11/04/2017 (Tuesday), 11:00-16:00
Place: QUTE Auditorium, Institute of Physics, Bratislava
  26.01.2017 seminar
NONLOCAL SEMINAR :: http://nlseminar.weebly.com ::
13:15-14:00 Siddharth Karumanchi (Brno): Conferencing encoders
14:30-15:15 Michal Sedlák (Bratislava): Storing and retrieving quantum channels
15:45-16:30 Matej Pivoluska (Vienna): On layered quantum key distribution

Date: 26/01/2017 (Thursday), 12:00-18:00
Place: RCQI, Bratislava
  17.01.2017 research paper
Exact quantum query complexity of EXACTk,ln
In the exact quantum query model a successful algorithm must always output the correct function value. We investigate the function that is true if exactly k or l of the n input bits given by an oracle are 1. We find an optimal algorithm (for some cases), and a nontrivial general lower and upper bound on the minimum number of queries to the black box.

by Andris Ambainis, Jānis Iraids, and Daniel Nagaj
in Lecture Notes in Computer Science 10139, SOFSEM 2017 (Springer, Cham 2017) | +++ |
APVV-14-0878 (QETWORK)
  12.01.2017 PhD defense
Public defense of our PhD student Michal Daniška of his thesis

     Study of classical and quantum phase transitions on non-euclidean
     geometries in higher dimensions

Supervisor: Dr. Andrej Gendiar
- doc. RNDr. Igor Medveď, PhD (Faculty of natural sciences UKF, Nitra)
- RNDr. Hana Čenčariková, PhD. (Ústav experimentálnej fyziky SAV, Košice)
- doc. RNDr. Martin Moško, DrSc. (Elektrotechnický ústav SAV, Bratislava)