arXiv subjects

Kian Maleki

Publications and source records attributed to Kian Maleki.

3 recordsLinked to original sources

arXiv2026

Calculations of current in the cotunneling regime using Lindblad equations

Transport through zero-dimensional states in a tunneling barrier can occur via co-tunneling, wherein a carrier occupying a state outside the range of energies between the chemical potentials of the two leads hops to a lead, and within the brief time permitted by the energy-time uncertainty relationship the occupancy is replenished from the other lead. Here, we calculate the current in such junctions using a Lindblad formalism within the Markovian approximation. We consider transport in the Coulomb blockade regime with spin-polarized leads and a magnetic field smaller than the coercive field of either lead. Dependences on magnetic field and lead spin polarization of the spin blockade, decoherence, and spin lifetime of the subsystems of this model are calculated.

cond-mat.mes-hall↗

arXiv2025

Crystal fields, exchange, and dipolar interactions and noncollinear magnons of erbium oxide

We simulate the properties of magnons in erbium oxide, a noncollinear antiferromagnet, from an effective single-ion Hamiltonian, including exchange and long-range dipolar interactions. We parametrize the crystal field splitting of Er$_2$O$_3$ using Steven's operators and obtain the effective symmetry-dependent exchange constants between different erbium ions quenched by the crystal field at different symmetry sites. We apply the Holstein-Primakoff transformation to the noncollinear spin system and employ paraunitary diagonalization for the effective spin Hamiltonian. The addition of the dipolar interaction to the exchange magnon dispersion changes the magnon bands drastically. The long-range nature of the dipolar interaction provides challenges to convergence, however we find that the averaged and normalized difference in the magnon dispersion is less than an averaged factor of $10^{-6}$ if the dipolar interaction is included out to the fortieth nearest neighbor.

cond-mat.mes-hall↗

arXiv2025

A general and modular approach to solid-state integration and readout of zero-dimensional quantum systems

Here, we present an all-electrical readout mechanism for quasi-0D quantum states (0D-QS) such as point defects, adatoms and molecules, that is modular and general, providing an approach that is amenable to scaling and integration with other solid-state quantum technologies. Our approach relies on the crea-tion of high-quality tunnel junctions via the mechanical exfoliation and stacking of multi-layer gra-phene (MLG) and hexagonal boron nitride (hBN) to encapsulate the target system in an MLG/hBN/0D-QS/hBN/MLG heterostructure. This structure allows for all-electronic spectroscopy and readout of candidate systems through a combination of coulomb and spin-blockade. As a proof of principle, we demonstrate electronic tunneling spectroscopy of point defects in hBN and the molecular qubit vanadyl phthalocyanine (VOPc). Our approach demonstrates a new pathway for the incorporation of molecules and atomic defects into solid-state quantum devices and circuits along with a readout scheme that does not rely on highly-constrained optical processes for photonic readout.

cond-mat.mtrl-sci↗