@article { ISI:000562002100002,
title = {Two-dimensional electron self-energy: Long-range Coulomb interaction},
journal = {Phys. Rev. B},
volume = {102},
number = {8},
year = {2020},
month = {AUG 24},
pages = {085145},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {The electron self-energy for long-range Coulomb interactions plays a crucial role in understanding the many-body physics of interacting electron systems (e.g., in metals and semiconductors) and has been studied extensively for decades. In fact, it is among the oldest and the most-investigated many-body problems in physics. However, there is a lack of an analytical expression for the self-energy Re Sigma((R)) (epsilon, T) when energy epsilon and temperature k(B)T are arbitrary with respect to each other (while both being still small compared with the Fermi energy). We revisit this problem and calculate analytically the self-energy on the mass shell for a two-dimensional electron system with Coulomb interactions in the high density limit r(s)<< 1, for temperature r(s)(3/2) << k(B)T/E-F << r(s) and energy r(s)(3/2) << vertical bar epsilon vertical bar << r(s). We provide the exact high-density analytical expressions for the real and imaginary parts of the electron self-energy with arbitrary value of epsilon/KBT, to the leading order in the dimensionless Coulomb coupling constant r(s), and to several higher than leading orders in k(B)T/r(s)E(F) and epsilon/r(s)E(F) . We also obtain the asymptotic behavior of the self-energy in the regimes vertical bar epsilon vertical bar << k(B)T and vertical bar epsilon vertical bar >> k(B)T. The higher-order terms have subtle and highly nontrivial compound logarithmic contributions from both epsilon and T, explaining why they have never before been calculated in spite of the importance of the subject matter.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.102.085145},
author = {Liao, Yunxiang and Buterakos, Donovan and Schecter, Mike and Das Sarma, Sankar}
}
@article { ISI:000504862300005,
title = {Coupled electron-impurity and electron-phonon systems as trivial non-Fermi liquids},
journal = {Phys. Rev. B},
volume = {100},
number = {23},
year = {2019},
month = {DEC 30},
pages = {235149},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We consider an electron gas, both in two (2D) and three (3D) dimensions, interacting with quenched impurities and phonons within leading order finite-temperature many-body perturbation theories, calculating the electron self-energies, spectral functions, and momentum distribution functions at finite temperatures. The resultant spectral function is in general highly non-Lorentzian, indicating that the system is not a Fermi liquid in the usual sense. The calculated momentum distribution function cannot be approximated by a Fermi function at any temperature, providing a rather simple example of a non-Fermi liquid with well-understood properties.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.100.235149},
author = {Buterakos, Donovan and Das Sarma, Sankar}
}
@article { ISI:000504435500005,
title = {Ferromagnetism in quantum dot plaquettes},
journal = {Phys. Rev. B},
volume = {100},
number = {22},
year = {2019},
month = {DEC 23},
pages = {224421},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Following recent experimental progress concerning Nagaoka ferromagnetism in finite-size quantum dot plaquettes, a general theoretical analysis is warranted in order to ascertain in rather generic terms which arrangements of a small number of quantum dots can produce saturated ferromagnetic ground states and under which constraints on interaction and interdot tunneling in the plaquette. This is particularly necessary since Nagaoka ferromagnetism is fragile and arises only under rather special conditions. We test the robustness of ground state ferromagnetism in the presence of a long-range Coulomb interaction and long-range as well as short-range interdot hopping by modeling a wide range of different plaquette geometries accessible by arranging a few (similar to 4) quantum dots in a controlled manner. We find that ferromagnetism is robust to the presence of long-range Coulomb interactions, and we develop conditions constraining the tunneling strength such that the ground state is ferromagnetic. Additionally, we predict the presence of a partially spin-polarized ferromagnetic state for 4 electrons in a Y-shaped 4-quantum-dot plaquette. Finally, we consider 4 electrons in a ring of 5 dots. This does not satisfy the Nagaoka condition; however, we show that the ground state is spin 1 for strong, but not infinite, on-site interaction. Thus, even though Nagaoka{\textquoteright}s theorem does not apply, the ground state for the finite system with one hole in a ring of 5 dots is partially ferromagnetic. We provide detailed fully analytical results for the existence or not of ferromagnetic ground states in several quantum dot geometries which can be studied in currently available coupled quantum dot systems.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.100.224421},
author = {Buterakos, Donovan and Das Sarma, Sankar}
}
@article {ISI:000478993000006,
title = {Simulation of the coupling strength of capacitively coupled singlet-triplet qubits},
journal = {Phys. Rev. B},
volume = {100},
number = {7},
year = {2019},
month = {AUG 6},
pages = {075411},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We consider a system of two purely capacitively coupled singlet-triplet qubits and numerically simulate the energy structure of four electrons in two double quantum dots with a large potential barrier between them. We calculate the interqubit coupling strength using an extended Hund-Mulliken approach which includes excited orbitals in addition to the lowest-energy orbital for each quantum dot. We show the coupling strength as a function of the qubit separation as well as plotting it against the detunings of the two double quantum dots and show that the general qualitative features of our results can be captured by a potential-independent toy model of the system.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.100.075411},
author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma}
}
@article { ISI:000423433700007,
title = {Crosstalk error correction through dynamical decoupling of single-qubit gates in capacitively coupled singlet-triplet semiconductor spin qubits},
journal = {PHYSICAL REVIEW B},
volume = {97},
number = {4},
year = {2018},
month = {JAN 29},
pages = {045431},
issn = {2469-9950},
doi = {10.1103/PhysRevB.97.045431},
author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma}
}
@article { ISI:000437110200003,
title = {Error correction for gate operations in systems of exchange-coupled singlet-triplet qubits in double quantum dots},
journal = {PHYSICAL REVIEW B},
volume = {98},
number = {3},
year = {2018},
month = {JUL 3},
pages = {035406},
issn = {2469-9950},
doi = {10.1103/PhysRevB.98.035406},
author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma}
}