J. H. Pixley
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View article: Separate Surface and Bulk Topological Anderson Localization Transitions in Disordered Axion Insulators
Separate Surface and Bulk Topological Anderson Localization Transitions in Disordered Axion Insulators Open
In topological phases of matter for which the bulk and boundary support distinct electronic gaps, there exists the possibility of decoupled mobility gaps in the presence of disorder. This is in analogy with the well-studied problem of real…
View article: Quantum criticality and tunable Griffiths phase in superconducting twisted trilayer graphene
Quantum criticality and tunable Griffiths phase in superconducting twisted trilayer graphene Open
When dimensionality is reduced, enhanced quantum fluctuations can destroy long-range phase coherence, driving a superconductor–insulator transition (SIT), where disorder and electronic correlations give rise to novel many-body states. Here…
View article: Spectrally sharp magnetic excitations above the critical temperature in a frustrated Weyl semimetal
Spectrally sharp magnetic excitations above the critical temperature in a frustrated Weyl semimetal Open
The rare-earth α-pyrochlore iridates are a prospective class of conducting frustrated magnets where electronic correlations, large spin-orbit coupling, and geometrical frustration interplay, leading to a rich set of magnetic and electronic…
View article: Complete Boundary Phase Diagram of the Spin-$\frac{1}{2}$ XXZ Chain with Boundary Fields in the Anti-Ferromagnetic Gapped Regime
Complete Boundary Phase Diagram of the Spin-$\frac{1}{2}$ XXZ Chain with Boundary Fields in the Anti-Ferromagnetic Gapped Regime Open
We consider the spin $\frac{1}{2}$ XXZ chain with diagonal boundary fields and solve it exactly using Bethe ansatz in the gapped anti-ferromagnetic regime and obtain the complete phase boundary diagram. Depending on the values of the bound…
View article: Electronic anisotropy and rotational symmetry breaking at a Weyl semimetal/spin ice interface
Electronic anisotropy and rotational symmetry breaking at a Weyl semimetal/spin ice interface Open
In magnetic pyrochlore materials, the interplay of spin-orbit coupling, electronic correlations, and geometrical frustration gives rise to exotic quantum phases, including topological semimetals and spin ice. While these phases have been o…
View article: Spin chain with non-Hermitian <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="script">PT</mml:mi></mml:math>-symmetric boundary couplings: Exact solution, dissipative Kondo effect, and phase transitions on the edge
Spin chain with non-Hermitian -symmetric boundary couplings: Exact solution, dissipative Kondo effect, and phase transitions on the edge Open
We construct an exactly solvable $\mathscr{PT}-$symmetric non-Hermitian model where a spin$-\frac{1}{2}$ isotropic quantum Heisenberg spin chain is coupled to two spin$-\frac{1}{2}$ Kondo impurities at its boundaries with coupling strength…
View article: Quasiparticle and superfluid dynamics in Magic-Angle Graphene
Quasiparticle and superfluid dynamics in Magic-Angle Graphene Open
Magic-Angle Twisted Bilayer Graphene (MATBG) shows a wide range of correlated phases which are electrostatically tunable. Despite a growing knowledge of the material, there is yet no consensus on the microscopic mechanisms driving its supe…
View article: Emulating moiré materials with quasiperiodic circuit quantum electrodynamics
Emulating moiré materials with quasiperiodic circuit quantum electrodynamics Open
Topological band structures interfering with moiré superstructures give rise to a plethora of emergent phenomena, which are pivotal for correlated insulating and superconducting states of twisttronics materials. While quasiperiodicity was …
View article: Control-driven critical fluctuations across quantum trajectories
Control-driven critical fluctuations across quantum trajectories Open
Monitored quantum circuits in which entangling unitary dynamics compete with projective local measurements can host measurement-induced phase transitions witnessed by entanglement measures at late times. Adding feedback conditioned on the …
View article: Twisted Nodal Superconductors
Twisted Nodal Superconductors Open
Recent proposals for the realization of time-reversal symmetry breaking and topological superconductivity in twisted nodal superconductors have led to a surge of theoretical and experimental studies of these systems, marking one of the new…
View article: Concomitant Entanglement and Control Criticality Driven by Collective Measurements
Concomitant Entanglement and Control Criticality Driven by Collective Measurements Open
Adaptive quantum circuits—where a quantum many-body state is controlled using measurements and conditional unitary operations—are a powerful paradigm for state preparation and quantum error-correction tasks. They can support two types of n…
View article: 2.5-dimensional topological superconductivity in twisted superconducting flakes
2.5-dimensional topological superconductivity in twisted superconducting flakes Open
Multilayer flakes of two-dimensional materials were recently shown to be tunable by twisting monolayers on their surface. This raises the question whether qualitatively new phenomena can occur in such finite-thickness moiré systems. Here w…
View article: Separate surface and bulk topological Anderson localization transitions in disordered axion insulators
Separate surface and bulk topological Anderson localization transitions in disordered axion insulators Open
In topological phases of matter for which the bulk and boundary support distinct electronic gaps, there exists the possibility of decoupled mobility gaps in the presence of disorder. This is in analogy with the well-studied problem of real…
View article: Decoupling the electronic gap from the spin Chern number in spin-resolved topological insulators
Decoupling the electronic gap from the spin Chern number in spin-resolved topological insulators Open
In two-dimensional topological insulators, a disorder-induced topological phase transition is typically identified with an Anderson localization transition at the Fermi energy. However, in Z2 trivial, spin-resolved topological insulators i…
View article: Edge modes and boundary impurities in the anisotropic Heisenberg spin chain
Edge modes and boundary impurities in the anisotropic Heisenberg spin chain Open
We present a comprehensive analysis of boundary phenomena in a spin-$\frac{1}{2}$ anisotropic Heisenberg chain (XXZ-$\frac{1}{2}$) in the gapped antiferromagnetic phase, with a particular focus on the interplay between fractionalized spin-…
View article: Infinitely fast critical dynamics: Teleportation through temporal rare regions in monitored quantum circuits
Infinitely fast critical dynamics: Teleportation through temporal rare regions in monitored quantum circuits Open
We consider measurement-induced phase transitions in monitored quantum circuits with a measurement rate that fluctuates in time. The spatially correlated fluctuations in the measurement rate disrupt the volume-law phase for low measurement…
View article: Electronic anisotropy and rotational symmetry breaking at a Weyl semimetal/spin ice interface
Electronic anisotropy and rotational symmetry breaking at a Weyl semimetal/spin ice interface Open
In magnetic pyrochlore materials, the interplay of spin-orbit coupling, electronic correlations, and geometrical frustration gives rise to exotic quantum phases, including topological semimetals and spin ice. While these phases have been o…
View article: Vacancy-Induced Tunable Kondo Effect in Twisted Bilayer Graphene
Vacancy-Induced Tunable Kondo Effect in Twisted Bilayer Graphene Open
In single sheets of graphene, vacancy-induced states have been shown to host an effective spin-1/2 hole that can be Kondo screened at low temperatures. Here, we show how these vacancy-induced impurity states survive in twisted bilayer grap…
View article: Moiré Periodic and Quasiperiodic Crystals in Heterostructures of Twisted Bilayer Graphene and Hexagonal Boron Nitride
Moiré Periodic and Quasiperiodic Crystals in Heterostructures of Twisted Bilayer Graphene and Hexagonal Boron Nitride Open
Stacking two atomic crystals with a twist between their crystal axes produces moiré potentials that modify the electronic properties. Here we show that double moiré potentials generated by superposing three atomic crystals create a new cla…
View article: Absence of quantization in the circular photogalvanic effect in disordered chiral Weyl semimetals
Absence of quantization in the circular photogalvanic effect in disordered chiral Weyl semimetals Open
The circularly polarized photogalvanic effect (CPGE) is studied in chiral Weyl semimetals with short-range quenched disorder. Without disorder, the topological properties of chiral Weyl semimetals lead to quantization of the CPGE, which is…
View article: The Kondo effect in the quantum XX spin chain
The Kondo effect in the quantum XX spin chain Open
We investigate the boundary phenomena that arise in a finite-size XX spin chain interacting through an XX interaction with a spin impurity located at its edge. Upon Jordan–Wigner transformation, the model is described by a quadratic …
View article: Local and nonlocal stochastic control of quantum chaos: Measurement- and control-induced criticality
Local and nonlocal stochastic control of quantum chaos: Measurement- and control-induced criticality Open
We theoretically study the topology of the phase diagram of a family of quantum models inspired by the classical Bernoulli map under stochastic control. The quantum models inherit a control-induced phase transition from the classical model…
View article: Direct topological insulator transitions in three dimensions are destabilized by nonperturbative effects of disorder
Direct topological insulator transitions in three dimensions are destabilized by nonperturbative effects of disorder Open
We reconsider the phase diagram of a three-dimensional ${\mathbb{Z}}_{2}$ topological insulator in the presence of short-ranged potential disorder, with the insight that nonperturbative rare states destabilize the noninteracting Dirac semi…
View article: Critical Properties of Weak Measurement Induced Phase Transitions in Random Quantum Circuits
Critical Properties of Weak Measurement Induced Phase Transitions in Random Quantum Circuits Open
The effects of different forms of weak measurements on the nature of the measurement induced phase transition are theoretically studied in hybrid random quantum circuits of qubits. We use a combination of entanglement measures, ancilla pur…
View article: Decoupling the electronic gap from the spin Chern number in disordered higher-order topological insulators
Decoupling the electronic gap from the spin Chern number in disordered higher-order topological insulators Open
In two-dimensional topological insulators, a disorder induced topological phase transition is typically identified with an Anderson localization transition at the Fermi energy. However, in higher-order, spin-resolved topological insulators…
View article: Boundary transfer matrix spectrum of measurement-induced transitions
Boundary transfer matrix spectrum of measurement-induced transitions Open
Measurement-induced phase transitions (MIPTs) are known to be described by nonunitary conformal field theories (CFTs) whose precise nature remains unknown. Most physical quantities of interest, such as the entanglement features of quantum …
View article: Vacancy-induced tunable Kondo effect in twisted bilayer graphene
Vacancy-induced tunable Kondo effect in twisted bilayer graphene Open
In single sheets of graphene, vacancy-induced states have been shown to host an effective spin-1/2 hole that can be Kondo-screened at low temperatures. Here, we show how these vacancy-induced impurity states survive in twisted bilayer grap…
View article: Long-ranged spectral correlations in eigenstate phases
Long-ranged spectral correlations in eigenstate phases Open
We study non-local measures of spectral correlations and their utility in characterizing and distinguishing between the distinct eigenstate phases of quantum chaotic and many-body localized systems. We focus on two related quantities, the …
View article: Time-reversal symmetry breaking superconductivity between twisted cuprate superconductors
Time-reversal symmetry breaking superconductivity between twisted cuprate superconductors Open
Twisted interfaces between stacked van der Waals (vdW) cuprate crystals present a platform for engineering superconducting order parameters by adjusting stacking angles. Using a cryogenic assembly technique, we construct twisted vdW Joseph…
View article: Quasiperiodic circuit quantum electrodynamics
Quasiperiodic circuit quantum electrodynamics Open
Superconducting circuits are an extremely versatile platform to realize quantum information hardware and to emulate topological materials. We here show how a simple arrangement of capacitors and conventional superconductor-insulator-superc…