14th Central European Quantum Information Processing Workshop
May 31st - June 3d 2017, Smolenice, Slovakia

Wednesday, 31.5.2017
17:30-19:00 EVENING SESSION (chaired by Mario Ziman)
17:30-18:10 I Časlav Brukner: Bell’s theorem for causal order   ΞΞΞ In all our theories it is assumed that the causal order of events is pre-defined. I will derive Bell’s inequalities that are fulfilled under the assumptions of definite causal order, locality and the “freedom of choice”. I will then show that the inequalities can be violated in an experimental scheme that involves both gravitational time dilation and quantum superposition. This implies that definite causal order might not be a fundamental ingredient of nature.
18:10-18:35 C Jedrzej Kaniewski: Self-testing of binary observables based on commutation
18:35-19:00 C Miriam Backens: A new Holant dichotomy inspired by quantum computation

Thursday, 1.6.2017
08:00-08:45 Breakfast
09:00-12:30 MORNING SESSION (chaired by Teiko Heinosaari)
09:00-09:40 I Otfried Guehne: Quantum correlations and the marginal problem   ΞΞΞThe question which properties of a global quantum state can be inferred from restricted information is central for many problems in quantum information processing. Especially the case that only the reduced quantum states (or marginals) are known is of relevance. In my talk, I will present several results on the relation between the marginals and the global quantum state. First, I will discuss for which cases the marginals determine the global state uniquely, either among all pure states or among all mixed states. Second, I will discuss cases, where global entanglement can be proved by considering the marginals only.
09:40-10:05 C Mariami Gachechialdze: Hypergraph states, their entanglement properties, local and nonlocal graphical transformations
10:05-10:30 C Julio de Vicente: Multipartite entanglement transformations with local operations and finite rounds of classical communication
10:30-11:00 Coffee & Refreshment
11:00-11:40 I Antonio Acin: General and projective measurements   ΞΞΞ General non-projective measurements provide an advantage over projective one in several applications. We show how they can also lead to improvement in the context of device-indepednent randomness generation allowing the extraction of more than one random bit from one quantum bit. We then discuss the simulation of general measurements with projective ones and show how these results can be used to improve existing local models on entangled quantum states.
11:40-12:05 C Milan Holzaepfel: Efficient tomography of a quantum many-body system
12:05-12:30 C Min-Hsiu Hsieh: Round Complexity in the Local Transformations of Quantum and Classical States
12:30-13:30 Lunch
14:00-16:20 AFTERNOON SESSION (chaired by Zolán Zimborás)
14:00-14:25 C Aurél Gábris: Demonstrating measurement induced effects in a quantum walk simulator
14:25-14:50 C Daniel Reitzner: Navigating a Maze Using Quantum-Walk Searches
14:50-15:15 C Dominik Hangleiter: Architectures for quantum simulation showing quantum supremacy
15:15-15:40 Coffee & Refreshment
15:40-16:05 C Roope Uola: Probing quantum steering through incompatible quantum measurements
16:05-16:30 C Tomáš Rybár: Incompatibility of qubit observables and unital qubit channels
16:30-18:30 POSTER SESSION
18:30 DINNER
19:00-23:00 CIPHER GAME (18:30 registration)

Friday, 2.6.2017
08:00-08:45 Breakfast
09:00-12:30 MORNING SESSION (chaired by Otfried Guehne)
09:00-09:40 I Sergey N. Filippov: Entangling and disentangling properties of quantum dynamical maps   ΞΞΞ We review general properties of quantum channels related with their action on entanglement. We introduce the class of entanglement-inducing channels whose output is always entangled. The opposite effect is produced by entanglement-annihilating channels that degrade entanglement completely. Entanglement robustness to local non-unital noises is revisited and new classes of maximally robust states are presented. We review criteria for absolutely separating channels, which result in separable states that cannot be made entangled by any unitary operations. The implications for entanglement-based applications are discussed.
09:40-10:05 C Matthias Kleinmann: Testing the structure of quantum theory
10:05-10:30 C Sukhwinder Singh: Entanglement and nonlocality of infinite 1D systems
10:30-11:00 Coffee & Refreshment
11:00-11:40 I Fred Dupuis: Device-independent quantum cryptography via entropy accumulation   ΞΞΞ Proving security of device-independent (DI) cryptographic protocols has been regarded a complex and tedious task. The main difficulty consists in analysing how the eavesdropper's uncertainty "accumulates" through many repetitions of a basic test, or "entropy-generating" block, on which the protocol is based. Previous satisfactory quantitative bounds were restricted to the case where the repetitions are independent, a strong and often unwarranted assumption. Our main contribution is a general information-theoretic result, the "entropy accumulation theorem", which shows that entropy accumulation occurs in quite general settings in which there is no independence assumption. Our theorem is relevant for applications: we give simple and modular security proofs for DI randomness generation and quantum key distribution. For both tasks we establish essentially optimal key rates and noise tolerance. As loophole-free Bell tests are finally being realised, our results considerably decrease the gap between theory and experiments, thereby marking an important step towards practical DI protocols and their implementation.
11:40-12:05 C Michal Sedlák: Perfect probabilistic storing and retrieving of unitary channels
12:05-12:30 C Philippe Guerin: Exponential communication complexity advantage from quantum superposition of the direction of communication
12:30-13:30 Lunch

Saturday, 3.6.2016
09:00-09:30 Breakfast
09:30-10:20 MORNING SESSION (chaired by Daniel Reitzner)
09:30-09:55 C Gael Sentís: Exact Quantum Change Point Detection
09:55-10:20 C Máté Farkas: QRAC strategies and an extension of the MUB condition
10:20-10:30 Take Away Refreshment
10:30-13:30 Conference bus
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