Doctoral theses
Current Record: 16 of 2468
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Identifier |
000465254 |
Title |
Extraction and stabilization of quantum many-body states |
Alternative Title |
Απόσπαση και σταθεροποίηση κβαντικών καταστάσεων πολλών σωματιδίων |
Author
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Φραντζεσκάκης, Ραφαήλ Ι
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Thesis advisor
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Γεωργακίλας, Αλέξανδρος
Economou, Sophia
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Reviewer
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Κομίνης, Ιωάννης
Τσιρώνης, Γεώργιος
Νιάρχος, Βασίλειος
Petrosyan, David
Νικολόπουλος, Γεώργιος
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Abstract |
“Graph” states are highly entangled quantum states that are crucial resources in measurement - based quantum computing and quantum
communications. Despite the importance of photonic graph and cluster states for quantum technologies, their generation presents considerable
difficulties and it is a matter of current research.
In this dissertation, we propose two entanglement concentration protocols where we extract graph states from noisy graph states called
weighted graph states. In the first protocol, we initialize an 1D weighted graph state and by measuring the even number of qubits we are able to
extract GHZ states. We also study how single-qubit errors affect the protocol and if the extraction is sufficient in the presence of this type of
error. In the second protocol, we generalize our first result and show that we can extract more general states. In particular, we apply an edge
extraction for every edge of the graph state by replacing it with a weighted graph state and measuring three qubits for each edge. We comment
on the success probability of the protocol and we explore possible adaptive measurements in order to boost the success rate.
In the second part of the thesis, we study non-equilibrium quantum systems. Specifically, we define what a discrete-time-crystal phase is and
how to identify one. We study a central spin system that arises naturally in the different physical platforms and the possibility of observing a
time crystal phase in the presence of Heisenberg interactions. We show that a large Zeeman splitting mismatch between the central spin and the
satellite spins can be beneficial to stabilize computational basis quantum states and observe a time crystal. In the other method, we apply spinlocking pulses to the central spin to decouple the system dynamically from the in-plane interactions and be able to generate a time crystal
phase.
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Language |
English |
Subject |
Discrete time crystals |
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Entanglement concentration |
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Graph states |
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Γράφοι |
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Διακριτοί χρονοκρύσταλλοι |
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Συγκέντρωση σύμπλεξης |
Issue date |
2024-06-10 |
Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
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Type of Work--Doctoral theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/f/7/6/metadata-dlib-1718004867-221712-6548.tkl
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Views |
135 |
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