@article{bartkiewicz_synergic_2023,
title = {Synergic quantum generative machine learning},
author = {Karol Bartkiewicz and Patrycja Tulewicz and Jan Roik and Karel Lemr},
url = {https://www.nature.com/articles/s41598-023-40137-1},
doi = {10.1038/s41598-023-40137-1},
issn = {2045-2322},
year = {2023},
date = {2023-08-09},
urldate = {2023-10-18},
journal = {Scientific Reports},
volume = {13},
number = {1},
pages = {12893},
abstract = {We introduce a new approach towards generative quantum machine learning significantly reducing the number of hyperparameters and report on a proof-of-principle experiment demonstrating our approach. Our proposal depends on collaboration between the generators and discriminator, thus, we call it quantum synergic generative learning. We present numerical evidence that the synergic approach, in some cases, compares favorably to recently proposed quantum generative adversarial learning. In addition to the results obtained with quantum simulators, we also present experimental results obtained with an actual programmable quantum computer. We investigate how a quantum computer implementing generative learning algorithm could learn the concept of a maximally-entangled state. After completing the learning process, the network is able both to recognize and to generate an entangled state. Our approach can be treated as one possible preliminary step to understanding how the concept of quantum entanglement can be learned and demonstrated by a quantum computer.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Tulewicz2022,
title = {Spintronic transport through a double quantum dot-based spin valve with noncollinear magnetizations},
author = {Patrycja Tulewicz and Kacper Wrześniewski and Ireneusz Weymann},
url = {https://www.sciencedirect.com/science/article/pii/S0304885321010118},
doi = {10.1016/j.jmmm.2021.168788},
year = {2022},
date = {2022-03-15},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {546},
pages = {168788},
abstract = {We study the magnetoresistive properties of a spin valve based on a double quantum dot attached to ferromagnetic leads with noncollinear alignment of magnetic moments. It is assumed that each dot is strongly coupled to its own ferromagnetic electrode, while the hopping between the dots is relatively weak. The calculations are performed by using the perturbation theory in the coupling between the dots, while the local density of states of a quantum dot attached to a given external lead is determined with the aid of the numerical renormalization group method. We demonstrate that the examined device can exhibit considerable positive or inverse tunnel magnetoresistance. It can be also a source of highly spin-polarized current. Importantly, the spin-resolved transport properties can be controlled by gate and bias voltages and depend on the angle between the magnetizations of the ferromagnets.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Tulewicz2021,
title = {Large Voltage-Tunable Spin Valve Based on a Double Quantum Dot},
author = {Patrycja Tulewicz and Kacper Wrześniewski and Szabolcs Csonka and Ireneusz Weymann},
url = {https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.16.014029},
doi = {https://doi.org/10.1103/PhysRevApplied.16.014029},
year = {2021},
date = {2021-07-12},
journal = {Phys. Rev. Applied},
volume = {16},
pages = {014029},
abstract = {We study the spin-dependent transport properties of a spin valve based on a double quantum dot. Each quantum dot is assumed to be strongly coupled to its own ferromagnetic lead, while the coupling between the dots is relatively weak. The current flowing through the system is determined within perturbation theory in the hopping between the dots, whereas the spectrum of a quantum-dot–ferromagnetic-lead subsystem is determined by means of the numerical renormalization group method. The spin-dependent charge fluctuations between ferromagnets and quantum dots generate an effective exchange field, which splits the double-dot levels. Such a field can be controlled, separately for each quantum dot, by the gate voltages or by changing the magnetic configuration of the external leads. We demonstrate that the considered double-quantum-dot spin-valve setup exhibits enhanced magnetoresistive properties, including both normal and inverse tunnel magnetoresistance. We also show that this system allows for the generation of highly spin-polarized currents, which can be controlled by purely electrical means. The considered double quantum dot with ferromagnetic contacts can thus serve as an efficient voltage-tunable spin valve characterized by high output parameters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}