arXiv subjects

Elif Yunt

Publications and source records attributed to Elif Yunt.

5 recordsLinked to original sources

arXiv2026

Distribution of Bell State Entanglement in Qubit Networks via Collision Models

We investigate the selective generation of Bell-pair entanglement in three qubit networks using a standard quantum collision model. By varying the network geometry, the node contacted by the ancilla, and the interaction Hamiltonians, we identify configurations in which high pairwise concurrence and Bell state fidelity are generated between different target qubits, including nonadjacent qubits and qubits not directly coupled to the ancilla. For comparison, we also consider the continuous time unitary evolution of the complete ancilla network system, sampled at the same discrete time intervals. This reference calculation clarifies how discarding each outgoing ancilla and removing its correlations from subsequent dynamics modifies the attainable entanglement and preparation time. Our results provide a proof of principle demonstration of geometry dependent Bell pair generation and routing in small qubit networks.

quant-ph↗

arXiv2020

Internal Geometric Friction in a Kitaev Chain Heat Engine

We investigate a heat engine with a finite-length Kitaev chain in an ideal Otto cycle. It is found that the critical point of the topological phase transition coincides with the maxima of the efficiency and work output of the total Otto engine. Finite-size effects are taken into account using the method of Hill's nanothermodynamics, as well as using the method of temperature-dependent energy levels. We identify the bulk and boundary thermal cycles of the Kitaev chain engine and find that they are non-ideal Otto cycles. The physics of deviation from ideal Otto cycle is identified as a finite size effect, which we dub as "internal geometric friction", leading to heat transfer from the bulk to the boundary during adiabatic transformation of the whole system. Besides, we determine the regimes allowing for independently running an ideal Otto refrigerator at the boundary and an ideal Otto engines in the bulk and in the whole system. Furthermore, we show that the first-order phase transition in the boundary and the second-order phase transition in the bulk can be identified through their respective contributions to the engine work output.

cond-mat.stat-mech↗

arXiv2019

Topological and Finite Size Effects in a Kitaev Chain Heat Engine

We investigate a heat engine with a finite length Kitaev chain in an Otto cycle. Finite size effects are taken into account using method of Hill's nano-thermodynamics as well as using the method of temperature dependent energy levels. We distinguish the bulk and boundary contributions to the efficiency and the work output of Kitaev chain engine and identify them as non-Otto heat engine and refrigerator cycles, respectively. Possibility of separately running Otto engine cycles associated with the bulk and the whole system, and an Otto refrigerator at the boundary is pointed out. It is found that the critical point of the topological phase coincides with the extremum of the efficiency and the work output of the bulk and the total Otto engine.

cond-mat.stat-mech↗

arXiv2018

Topological Phase Transition in Quantum Heat Engine Cycles

We explore signatures of a topological phase transition (TPT) in the work and efficiency of a quantum heat engine, which uses a single layer topological insulator, stanene, in an external electric field as a working substance. The magnitude of the electric field controls the trivial and topological insulator phases of the stanene. We investigate the effects of TPT in two types of thermodynamic cycles, with and without adiabatic stages. For the adiabatic case, we examine a quantum Otto cycle. We find that at the critical point of TPT both work and efficiency plots with respect to the strength of the electric field exhibit a kink. For a non-adiabatic case, we consider an idealized Stirling type cycle with two isothermal and two isoelectric processes. We find no signatures of the TPT unless a voltage bias is introduced to restrict the involved energy bands to the electronic manifold above the Fermi level. In this case, either above or below the critical point, both work and efficiency become zero depending on the relative magnitudes of the electric fields in the isoelectric stages.

quant-ph↗

arXiv2016

Relation Between the Spin Hall Conductivity and the Spin Chern Number for Dirac-like Systems

A semiclassical formulation of the spin Hall effect for physical systems satisfying Dirac-like equation is introduced. We demonstrated that the main contribution to the spin Hall conductivity is given by the spin Chern number whether the spin is conserved or not at the quantum level. We illustrated the formulation within the Kane-Mele model of graphene in the absence and in the presence of the Rashba spin-orbit coupling term.

math-ph↗