@article { WOS:000704419000003,
title = {Fragile versus stable two-dimensional fermionic quasiparticles},
journal = {Phys. Rev. B},
volume = {104},
number = {12},
year = {2021},
month = {SEP 13},
publisher = {AMER PHYSICAL SOC},
type = {Editorial Material},
abstract = {We provide a comprehensive theoretical investigation of the Fermi liquid quasiparticle description in two-dimensional electron gas interacting via the long-range Coulomb interaction by calculating the electron self-energy within the leading-order approximation, which is exact in the high-density limit. We find that the quasiparticle energy is larger than the imaginary part of the self-energy up to very high energies, implying that the basic Landau quasiparticle picture is robust up to far above the Fermi energy. We find, however, that the quasiparticle picture becomes fragile in a small discrete region around a critical wave vector where the quasiparticle spectral function strongly deviates from the expected quasiparticle Lorentzian line shape with a vanishing renormalization factor. We show that such a non-Fermi liquid behavior arises due to the coupling of quasiparticles with the collective plasmon mode. This situation is somewhat intermediate between the one-dimensional interacting electron gas (i.e., Luttinger liquid), where the Landau Fermi liquid theory completely breaks down since only bosonic collective excitations exist, and three-dimensional electron gas, where quasiparticles are well-defined and more stable against interactions than in one and two dimensions. We use a number of complementary definitions for a quasiparticle to examine the interacting spectral function, contrasting two-dimensional and three-dimensional situations critically.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.104.125118},
author = {Ahn, Seongjin and Das Sarma, Sankar}
}
@article { ISI:000529804100001,
title = {Ferromagnetism and superconductivity in twisted double bilayer graphene},
journal = {Phys. Rev. B},
volume = {101},
number = {15},
year = {2020},
month = {APR 30},
pages = {155149},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We present a theory of competing ferromagnetic and superconducting orders in twisted double bilayer graphene. In our theory, ferromagnetism is induced by Coulomb repulsion, while superconductivity with intervalley equal-spin pairing can be mediated by electron-acoustic phonon interactions. We calculate the transition temperatures for ferromagnetism and superconductivity as a function of moire band filling factor, and find that superconducting domes can appear on both the electron and hole sides of the ferromagnetic insulator at half filling. We show that the ferromagnetic insulating gap has a dome shape dependence on the layer potential difference, which provides an explanation to the experimental observation that the ferromagnetic insulator only develops over a finite range of external displacement field. We also verify the stability of the half filled ferromagnetic insulator against two types of collective excitations, i.e., spin magnons and valley magnons.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.101.155149},
author = {Wu, Fengcheng 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:000457058500007,
title = {Fractional Josephson effect with and without Majorana zero modes},
journal = {Phys. Rev. B},
volume = {99},
number = {3},
year = {2019},
month = {JAN 29},
pages = {035312},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {It is known that the low-energy physics of the Josephson effect in the presence of Majorana zero modes exhibits a 4 pi periodicity as the Aharonov-Bohm flux varies in contrast to the 2 pi Josephson periodicity in usual superconducting junctions. We study this fractional Josephson effect in one-dimensional topological superconductors in Majorana nanowire systems by focusing on the features of the phase-energy relations in a superconducting semiconductor nanowire with spin-orbital coupling by including different factors operational in experimental systems, such as short wire length, suppression of superconducting gap, and the presence of an Andreev bound state. We show that even in the absence of the Majorana zero modes, some nontopological physical effects can manifest a 4 pi periodicity of the phase-energy relation in the Josephson junction, thus providing an alternative physics for fractional Josephson effect with no underlying Majorana zero modes. Furthermore, we consider several scenarios of inhomogeneous chemical potential distributions in the superconducting nanowire leading to four Majorana bound states and construct the effective four-Majorana model to correctly describe the low-energy theory of the Josephson effect. In this setup, multiple Majorana zero modes can also have the 4 pi fractional Josephson effect, although the underlying physics arises from Andreev bound states since two close-by Majorana bound states effectively form Andreev bound states. Our work demonstrates that the mere observation of a fractional Josephson effect simulating 4 pi periodicity might not, by itself, be taken as the definitive evidence for topological superconductivity. This finding has important implications for the ongoing search for non-Abelian Majorana zero modes and efforts for developing topological qubits.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.99.035312},
author = {Chiu, Ching-Kai and S. Das Sarma}
}
@article { ISI:000446554000001,
title = {Failure of Kohn{\textquoteright}s theorem and the apparent failure of the f-sum rule in intrinsic Dirac-Weyl materials in the presence of a filled Fermi sea},
journal = {PHYSICAL REVIEW B},
volume = {98},
number = {15},
year = {2018},
month = {OCT 5},
pages = {155112},
issn = {2469-9950},
doi = {10.1103/PhysRevB.98.155112},
author = {Throckmorton, Robert E. and S. Das Sarma}
}
@article { ISI:000415568700001,
title = {Fast pulse sequences for dynamically corrected gates in singlet-triplet qubits},
journal = {PHYSICAL REVIEW B},
volume = {96},
number = {19},
year = {2017},
month = {NOV 17},
issn = {2469-9950},
doi = {10.1103/PhysRevB.96.195424},
author = {Throckmorton, Robert E. and Zhang, Chengxian and Yang, Xu-Chen and Wang, Xin and Barnes, Edwin and S. Das Sarma}
}
@article { ISI:000379647900004,
title = {Fast control of semiconductor qubits beyond the rotating-wave approximation},
journal = {PHYSICAL REVIEW A},
volume = {94},
number = {1},
year = {2016},
month = {JUL 14},
issn = {2469-9926},
doi = {10.1103/PhysRevA.94.012321},
author = {Song, Yang and Kestner, J. P. and Wang, Xin and S. Das Sarma}
}
@article { ISI:000333559400002,
title = {Ferromagnetic response of a {\textquoteleft}{\textquoteleft}high-temperature{{\textquoteright}{\textquoteright}} quantum antiferromagnet},
journal = {PHYSICAL REVIEW B},
volume = {89},
number = {12},
year = {2014},
month = {MAR 31},
pages = {121118},
issn = {1098-0121},
doi = {10.1103/PhysRevB.89.121118},
author = {Wang, Xin and Sensarma, Rajdeep and S. Das Sarma}
}
@article { ISI:000314683100005,
title = {Finite temperature inelastic mean free path and quasiparticle lifetime in graphene},
journal = {Phys. Rev. B},
volume = {87},
number = {8},
year = {2013},
month = {FEB 5},
issn = {1098-0121},
doi = {10.1103/PhysRevB.87.085406},
author = {Li, Qiuzi and S. Das Sarma}
}
@article { ISI:000286768100007,
title = {Fractional quantum Hall effects in bilayers in the presence of interlayer tunneling and charge imbalance},
journal = {PHYSICAL REVIEW B},
volume = {82},
number = {23},
year = {2010},
month = {DEC 9},
issn = {1098-0121},
doi = {10.1103/PhysRevB.82.235312},
author = {Peterson, Michael R. and Papic, Z. and S. Das Sarma}
}
@article { ISI:000274664500043,
title = {Fractional Quantum Hall State at nu=5/2 and the Moore-Read Pfaffian},
journal = {PHYSICAL REVIEW LETTERS},
volume = {104},
number = {7},
year = {2010},
month = {FEB 19},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.104.076803},
author = {Storni, M. and Morf, R. H. and S. Das Sarma}
}
@article {Lee2010,
title = {F-wave pairing of cold atoms in optical lattices},
journal = {Phys. Rev. A},
volume = {82},
number = {5},
year = {2010},
month = {nov},
keywords = {2010, Single Fellow},
issn = {1050-2947},
url = {http://pra.aps.org/abstract/PRA/v82/i5/e053611},
author = {Lee, Wei-Cheng and Wu, Congjun and S. Das Sarma}
}
@article { ISI:000257424700054,
title = {Finite-layer thickness stabilizes the Pfaffian state for the 5/2 fractional quantum Hall effect: Wave function overlap and topological degeneracy},
journal = {PHYSICAL REVIEW LETTERS},
volume = {101},
number = {1},
year = {2008},
month = {JUL 4},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.101.016807},
author = {Peterson, Michael. R. and Jolicoeur, Th. and S. Das Sarma}
}
@article {Wu2007,
title = {Flat Bands and Wigner Crystallization in the Honeycomb Optical Lattice},
journal = {Phys. Rev. Lett.},
volume = {99},
number = {7},
year = {2007},
month = {aug},
keywords = {2007, Single Fellow},
issn = {0031-9007},
url = {http://prl.aps.org/abstract/PRL/v99/i7/e070401},
author = {Wu, Congjun and Doron L. Bergman and Balents, Leon and S. Das Sarma}
}