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 |
  24.07.2014 Research publication
Fault-ignorant quantum search
We investigate the problem of quantum searching on a noisy quantum computer. Taking a fault-ignorant approach, we analyze quantum algorithms that solve the task for various different noise strengths, which are possibly unknown beforehand. We prove lower bounds on the runtime of such algorithms and thereby find that the quadratic speedup is necessarily lost (in our noise models). However, for low but constant noise levels the algorithms we provide (based on Grover's algorithm) still outperform the best noiseless classical search algorithm.
by Péter Vrana, David Reeb, Daniel Reitzner and Michael M Wolf
New J. Phys. 16, 073033 (2014) |+++|
NONE
  02.07.2014 Research publication (PRA Editor's suggestion)
Entanglement sensitivity to signal attenuation and amplification
We analyze general laws of continuous-variable entanglement dynamics during the deterministic attenuation and amplification of the physical signal carrying the entanglement. These processes are inevitably accompanied by noises, so we find fundamental limitations on noise intensities that destroy entanglement of Gaussian and non-Gaussian input states. The phase-insensitive amplification Φ1⊗Φ2⊗⋯ΦN with the power gain ki≥2 (≈3 dB, i=1,...,N) is shown to destroy entanglement of any N-mode Gaussian state even in the case of quantum-limited performance. In contrast, we demonstrate non-Gaussian states with the energy of a few photons such that their entanglement survives within a wide range of noises beyond quantum-limited performance for any degree of attenuation or gain. We detect entanglement preservation properties of the channel Φ1⊗Φ2, where each mode is deterministically attenuated or amplified. Gaussian states of high energy are shown to be robust to very asymmetric attenuations, whereas non-Gaussian states are at an advantage in the case of symmetric attenuation and general amplification. If Φ1=Φ2, the total noise should not exceed 0.5(1+k2)1/2 to guarantee entanglement preservation.
by Sergey N. Filippov and Mário Ziman
Phys. Rev. A 90, 010301(R) (2014) |+++|
QIMABOS (APVV-0808-12)
  15.03.2014 Summer school
Qute-Europe Summer School 2014 (QESS 2014)
Starting your graduate in quantum information science and looking for right move for your PhD study? Come to our school on current challenges and elementary paradigms of quantum information processing. The school is organized from 18-28 August in charming Smolenice castle (Slovakia). To learn more details visit the school website http://quantum.physics.sk/conf/qess2014/. Support (provided by QUTE-EUROPE Coordination Action) is available and early deadline is 15/04/2014.
  21.02.2014 Conference
CEQIP 2014
This year in Znojmo (Czech republic), 5-8 June. Traditionally, excellent speakers, unforgettable athmosphere, delicious food and wine testing, unbreakable cipher game, adrenalyn underground experience, etc. Check more details on workshop website http://ceqip.eu/. Deadline for submission is April, 1st, seriously :-)
S E M I N A R S | more |
30/05 10:30
Peter Šiffalovič (Bratislava)
Novel materials based on nanoparticles and thin films

02/06 10:30
Errka Haapasalo (Turku)
Boundariness

03/06 13:00
Mikko Tukiainen (Turku)
Programmable Quantum Multimeters
V I S I T O R S | history |


28.05-14.06 Erkka Haapasalo
(University of Turku, Finland)

28.05-14.06 Mikko Tukiainen
(University of Turku, Finland) 08.06-12.06 Daniel Burgarth
(Aberystwyth University, Aberystwyth, United Kingdom)

09.06-12.06 Marcus Cramer
(University of Ulm, Germany)

27.06-03.07 Teiko Heinosaari
(University of Turku, Finland)






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