arXiv subjects

T. Farajollahpour

Publications and source records attributed to T. Farajollahpour.

6 recordsLinked to original sources

arXiv2026

Quantum Algorithm Software for Condensed Matter Physics

Realizing the promise of quantum computation for condensed matter many-body problems depends as much on software as on hardware, yet the area is reviewed far more often than it is quantified. We address this gap by pairing a focused survey of quantum algorithm software for condensed matter physics with a compact, fully reproducible benchmark suite that turns qualitative claims into concrete numbers. Each algorithm family, namely the variational quantum eigensolver (VQE), quantum phase estimation (QPE), quantum annealing and the quantum approximate optimization algorithm (QAOA), and quantum machine learning (QML), is demonstrated on a canonical lattice model and validated against an independent classical reference, from exact diagonalization and the Bethe ansatz to matrix-product-state DMRG. Within this suite we quantify two issues usually treated only qualitatively. Mapping the Fermi-Hubbard model to qubits under the Jordan-Wigner and Bravyi-Kitaev encodings, we tabulate qubit counts, operator weights, and gate costs and expose a geometry-dependent trade-off between the two. Simulating the circuits under a depolarizing noise model, we show that zero-noise extrapolation restores ground-state energies and optimization quality across the noise range. Around these results we review the algorithms as applied to strongly correlated systems, topological phases, and quantum magnetism, together with the leading software development kits (Qiskit, Cirq, PennyLane, and Q\#) and the classical and tensor-network methods against which quantum approaches must be benchmarked. All circuits, seeds, and data are released so the benchmarks can be reproduced and extended. We argue that standardized, reproducible benchmarks of this kind are essential to gauge progress and identify genuine quantum advantage in condensed matter physics.

cond-mat.str-el↗

arXiv2026

Three Quantum-Geometric Contributions to Cubic Orbital Magnetization

In noncentrosymmetric metals such as $C_{3v}$ topological-insulator surfaces, moiré heterobilayers, and zincblende crystals, point-group symmetry can forbid the linear and quadratic electric-field-induced orbital magnetization, leaving the cubic response as the leading signal. Using a Ward-complete finite-momentum cubic Kubo kernel with an antisymmetric linear-in-$q$ projection, we show that the dc response separates into three quantum-geometric channels. These are a mixed electric-magnetic positional-shift quadrupole, a quantum-metric drift term, and an orbital-moment octupole. The three contributions share the same point-group symmetry but differ in their lifetime, frequency, and gate fingerprints. For a warped $C_{3v}$ surface the metric channel obeys the cutoff-independent law $\barχ_G \propto μ^{-2}$. We propose third-harmonic magneto-optical Kerr spectroscopy as an experimental route.

cond-mat.mes-hall↗

arXiv2025

Berry curvature-induced transport signature for altermagnetic order

Altermagnetism has been detected in several materials using spin-sensitive probes. These measurements require rather complex setups that make it challenging to track variations in altermagnetic order, e.g., to identify a temperature-tuned altermagnetic phase transition. We propose a simple transport measurement that can probe the order parameter for $d$-wave altermagnetism. We suggest magnetoconductivity anisotropy -- the difference between the two principal values of the magnetoconductivity tensor. This quantity can be easily measured as a function of temperature, without any spin-selective apparatus. It acquires a nonzero value in a $C_4K$ phase, where $C_4$ rotations and time reversal $K$ are not symmetries but their combination is. This effect can be traced to the modification of phase space density due to Berry curvature, which we demonstrate using semiclassical equations of motion for band electrons. As an illustration, we build a minimal tight-binding model with altermagnetic order that breaks $C_4$ and $K$ symmetries while preserving $C_4K$.

cond-mat.mes-hall↗

arXiv2018

Topological phase transiton of anisotropic XY model with Dzyaloshinskii-Moriya interaction

Within the real space renormalization group we obtain the phase portrait of the anisotropic quantum XY model on square lattice in presence of Dzyaloshinskii-Moriya (DM) interaction. The model is characterized by two parameters, $λ$ corresponding to XY anisotropy, and $D$ corresponding to the strength of DM interaction. The flow portrait of the model is governed by two global Ising-Kitaev attractors at $(λ=\pm1,D=0)$ and a repeller line, $λ=0$. Renormalization flow of concurrence suggests that the $λ=0$ line corresponds to a topological phase transition. The gap starts at zero on this repeller line corresponding to super-fluid phase of underlying bosons; and flows towards a finite value at the Ising-Kitaev points. At these two fixed points the spin fields become purely classical, and hence the resulting Ising degeneracy can be interpreted as topological degeneracy of dual degrees of freedom. The state of affairs at the Ising-Kitaev fixed point is consistent with the picture of a p-wave pairing of strength $λ$ of Jordan-Wigner fermions coupled with Chern-Simons gauge fields.

cond-mat.str-el↗

arXiv2017

Anisotropic Friedel oscillations in graphene-like materials: The Dirac point approximation in wave-number dependent quantities revisited

Friedel oscillations of the graphene-like materials are investigated theoretically beyond the Dirac point-approximation. Numerical calculations have been performed within the random phase approximation (RPA). For intra-valley transitions it was demonstrated that the contribution of the different Dirac points in the wave-number dependent quantities, such as dielectric function $ε(q)$, has been determined by the orientation of the wave-number with respect to the Dirac point position vector in $k$-space. Therefore identical contribution of the different Dirac points is not automatically guaranteed by the degeneracy of the Hamiltonian at these points. Meanwhile it was shown that the contribution of the inter-valley transitions is always anisotropic even when the Dirac points coincide with the Fermi level ($E_F=0$). This means that the Dirac point approximation based studies give the correct physics only at high wave length limit. The anisotropy of the static dielectric function reveals different contribution of the each Dirac point. Additionally, the anisotropic $k$-space dielectric function results in anisotropic Friedel oscillations in graphene-like materials. Calculations have also been performed in the presence of the Rashba interaction. It was shown that increasing the Rashba interaction strength slightly modifies the Friedel oscillations in graphene-like materials. Therefore the anisotropic dielectric function in $k$-space is the clear manifestation of band anisotropy in the graphene-like systems.

cond-mat.mes-hall↗

arXiv2016

Emergence of electromotive force in precession-less rigid motion of deformed domain wall

Recently it has been recognized that the electromotive force (emf) can be induced just by the spin precession where the generation of the electromotive force has been considered as a real-space topological pumping effect. It has been shown that the amount of the electromotive force is independent of the functionality of the localized moments. It was also demonstrated that the rigid domain wall (DW) motion cannot generate electromotive force in the system. Based on real-space topological pumping approach in the current study we show that the electromotive force can be induced by rigid motion of a deformed DW. We also demonstrate that the generated electromotive force strongly depends on the DW bulging. Meanwhile results show that the DW bulging leads to generation of the electromotive force both along the axis of the DW motion and normal to the direction of motion.

cond-mat.mes-hall↗