762 citations · 3.3k across the 87 of their papers we have counts for
36 papers · 1 filter
Electrodynamic Signatures of Bogoliubov Fermi Surfaces in Moiré Graphene
Ke Wang, Qijin Chen, Rufus Boyack +1
Understanding the superfluid stiffness \(D_s\) is a central problem in flat-band superconductivity. It is often interpreted together with spectroscopic probes such as tunneling, si…
Anomalous Superfluid Density in Pair-Density-Wave Superconductors
Ke Wang, Qijin Chen, Rufus Boyack +1
Pair-density-wave (PDW) states are a long-sought-after phase of quantum materials, with the potential to unravel the mysteries of high- cuprates and other strongly correlated…
Universal approach to light driven "superconductivity" via preformed pairs
Ke Wang, Zhiqiang Wang, Qijin Chen +1
While there are many different mechanisms which have been proposed to understand the physics behind light induced ``superconductivity", what seems to be common to the class of mate…
Test for BCS-BEC Crossover in the Cuprate Superconductors
Qijin Chen, Zhiqiang Wang, Rufus Boyack +1
In this paper we address the question of whether high-temperature superconductors have anything in common with BCS-BEC crossover theory. Towards this goal, we present a proposal an…
When Superconductivity Crosses Over: From BCS to BEC
Qijin Chen, Zhiqiang Wang, Rufus Boyack +2
New developments in superconductivity, particularly through unexpected and often astonishing forms of superconducting materials, continue to excite the community and stimulate theo…
Unified approach to electrical and thermal transport in high- superconductors
Rufus Boyack, Zhiqiang Wang, Qijin Chen +1
In this paper we present a consolidated equation for all low-field transport coefficients, based on a reservoir approach developed for non-interacting quasiparticles. This formalis…
Quantum Geometric Contributions to the BKT Transition: Beyond Mean Field Theory
Zhiqiang Wang, Gaurav Chaudhary, Qijin Chen +1
We study quantum geometric contributions to the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature, , in the presence of fluctuations beyond BCS theory.…
Coexistence of nontrivial topological properties and strong ferromagnetic fluctuations in CrAs (=Na, K, Rb and Cs)
Chenchao Xu, Ninghua Wu, Guo-Xiang Zhi +5
Superconductivity in crystals without inversion symmetry has received extensive attention due to its unconventional pairing and possible nontrivial topological properties. Using fi…
Strong pairing in two dimensions: Pseudogaps, domes, and other implications
Xiaoyu Wang, Qijin Chen, K. Levin
This paper addresses the transition from the normal to the superfluid state in strongly correlated two dimensional fermionic superconductors and Fermi gases. We arrive at the Berez…
Electronic structure of Ni-doped EuRbFeAs: Unique crystal field splitting and multiband RKKY interactions
Chenchao Xu, Qijin Chen, Chao Cao
The relationship between magnetism and superconductivity has been one of the most discussed topics in iron-based superconductors. Using the first-principles calculations, we have s…
Combined effects of pairing fluctuations and a pseudogap in the Cuprate Hall effect
Rufus Boyack, Xiaoyu Wang, Qijin Chen +1
The normal-state behavior of the temperature-dependent Hall coefficient in cuprate superconductors is investigated using linear response theory. The Hall conductivity is of paramou…
Generalization of BCS theory to short coherence length superconductors: A BCS--Bose-Einstein crossover scenario
Qijin Chen
The (mean field based) BCS theory is considered one of the most successful theories in condensed matter physics. It is justified in ordinary metal superconductors the coherence len…
Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in three and two dimensions
Jibiao Wang, Yanming Che, Leifeng Zhang +1
The exotic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states have been actively searched for experimentally since the mean-field based FFLO theories were put forward half a century ag…
A Two Energy Gap Preformed-Pair Scenario For the Cuprates: Implications for Angle-Resolved Photoemission Spectroscopy
Chih-Chun Chien, Yan He, Qijin Chen +1
We show how, within a preformed pair scenario for the cuprate pseudogap, the nodal and antinodal responses in angle resolved photoemission spectroscopy necessarily have very differ…
Theory of Radio Frequency Spectroscopy Experiments in Ultracold Fermi Gases and Their Relation to Photoemission Experiments in the Cuprates
Qijin Chen, Yan He, Chih-Chun Chien +1
In this paper we present an overview of radio frequency (RF) spectroscopy in the atomic Fermi superfluids. An ultimate goal is to suggest new directions in the cold gas research ag…
Temperature and final state effects in radio frequency spectroscopy experiments on atomic Fermi gases
Yan He, Chih-Chun Chien, Qijin Chen +1
We present a systematic characterization of the radio frequency (RF) spectra of homogeneous, paired atomic Fermi gases at finite temperatures, , in the presence of final state i…
Understanding the Protected Nodes and Collapse of the Fermi Arcs in Underdoped Cuprate Superconductors
Qijin Chen, K. Levin
We show how recent angle resolved photoemission measurements addressing the Fermi arcs in the cuprates reveal a very natural phenomenological description of the complex superfluid…
What can ultracold Fermi gases teach us about high superconductors and vice versa?
K. Levin, Qijin Chen
We review recent developments in the field of ultracold atomic Fermi gases. As the cold atom system evolves from BCS to Bose-Einstein condensation (BEC), the behavior of the thermo…
Stability conditions and phase diagrams for two component Fermi gases with population imbalance
Qijin Chen, Yan He, Chih-Chun Chien +1
Superfluidity in atomic Fermi gases with population imbalance has recently become an exciting research focus. There is considerable disagreement in the literature about the appropr…
Ground State Description of a Single Vortex in an Atomic Fermi gas: From BCS to Bose-Einstein Condensation
Chih-Chun Chien, Yan He, Qijin Chen +1
We use a Bogoliubov-de Gennes (BdG) formulation to describe a single vortex in a neutral fermionic gas. It is presumed that the attractive pairing interaction can be arbitrarily tu…
Applying BCS-BEC Crossover Theory To High Temperature Superconductors and Ultracold Atomic Fermi Gases
Qijin Chen, Jelena Stajic, K. Levin
This review is written at the time of the twentieth anniversary of the discovery of high temperature superconductors, which, nearly coincides with the important discovery of the su…
Population of closed-channel molecules in trapped Fermi gases with broad Feshbach resonances
Qijin Chen, K. Levin
We compute the fraction of closed-channel molecules in trapped atomic Fermi gases, over the entire range of accessible fields and temperatures. We use a two-channel model of BCS--B…
Thermodynamics of Interacting Fermions in Atomic Traps
Qijin Chen, Jelena Stajic, K. Levin
We calculate the entropy in a trapped, resonantly interacting Fermi gas as a function of temperature for a wide range of magnetic fields between the BCS and Bose-Einstein condensat…
BCS-BEC Crossover: From High Temperature Superconductors to Ultracold Superfluids
Qijin Chen, Jelena Stajic, Shina Tan +1
We review the BCS to Bose Einstein condensation (BEC) crossover scenario which is based on the well known crossover generalization of the BCS ground state wavefunction . While…