scholarly journals Fundamental dissipation due to bound fermions in the zero-temperature limit

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Autti ◽  
S. L. Ahlstrom ◽  
R. P. Haley ◽  
A. Jennings ◽  
G. R. Pickett ◽  
...  
Keyword(s):  
Critical Velocity ◽  
Ground State ◽  
Bound States ◽  
Bound State ◽  
Temperature Limit ◽  
Pair Breaking ◽  
Zero Temperature ◽  
Andreev Bound States ◽  
Macroscopic Object

Abstract The ground state of a fermionic condensate is well protected against perturbations in the presence of an isotropic gap. Regions of gap suppression, surfaces and vortex cores which host Andreev-bound states, seemingly lift that strict protection. Here we show that in superfluid 3He the role of bound states is more subtle: when a macroscopic object moves in the superfluid at velocities exceeding the Landau critical velocity, little to no bulk pair breaking takes place, while the damping observed originates from the bound states covering the moving object. We identify two separate timescales that govern the bound state dynamics, one of them much longer than theoretically anticipated, and show that the bound states do not interact with bulk excitations.

scholarly journals Spin-polarized transport across aLa0.7Sr0.3MnO3/YBa2Cu3O7−xinterface: Role of Andreev bound states

2001 ◽  
Vol 63 (21) ◽  
Author(s):  
Z. Y. Chen ◽  
Amlan Biswas ◽  
Igor Žutić ◽  
T. Wu ◽  
S. B. Ogale ◽  
...  
Keyword(s):  
Bound States ◽  
Andreev Bound States ◽  
Spin Polarized ◽  
Polarized Transport ◽  
Spin Polarized Transport

Effect of Biquadratic Exchange Upon Ferromagnetic Two-Magnon Bound States. II. Anisotropic Exchange

1974 ◽  
Vol 52 (1) ◽  
pp. 33-39 ◽  
Author(s):  
D. A. Pink ◽  
R. Ballard
Keyword(s):  
Bound States ◽  
Exchange Interactions ◽  
Bound State ◽  
Exchange Term ◽  
Zero Temperature ◽  
Biquadratic Exchange ◽  
Anisotropic Exchange ◽  
Bound State Spectrum ◽  
Mode Pair ◽  
Isotropic Exchange

We have investigated the two-magnon bound state spectrum of a ferromagnetically ordered system for which the Hamiltonian contains an anisotropic bilinear exchange term, an anisotropic biquadratic exchange term, and a single-ion anisotropy term. The bound states, labelled by a wave vector q which we have taken to be in the [111] direction, were calculated by using zero-temperature Green functions. The principal results are: (i) the existence of single-ion bound states in the absence of single-ion anisotropy and conversely, their absence in the presence of such anisotropy, in contrast to the case in which the exchange interactions are isotropic; (ii) the appearance of an S mode for values of q, [Formula: see text]; (iii) the ordering of bound states for isotropic exchange interactions wherein the S0 mode lies below the S1-mode, D-mode pair and where the S1 mode lies below (above) the D mode if they lie below (above) the band, no longer holds.

scholarly journals Spatial Rabi oscillations between Majorana bound states and quantum dots

2018 ◽  
Vol 9 ◽  
pp. 1527-1535
Author(s):  
Jun-Hui Zheng ◽  
Dao-Xin Yao ◽  
Zhi Wang
Keyword(s):  
Quantum Dot ◽  
Bound States ◽  
Bound State ◽  
Double Quantum ◽  
Energy Splitting ◽  
Rabi Oscillations ◽  
Andreev Bound States ◽  
Majorana Bound States ◽  
Nonlocal Quantum ◽  
Equal Amplitude

Background: A Majorana bound state is a superconducting quasiparticle that is the superposition of particle and hole with equal amplitude. We propose a verification of this amplitude equality by analyzing the spatial Rabi oscillations of the quantum states of a quantum dot that is tunneling-coupled to the Majorana bound states. Results: We find two resonant Rabi driving energies that correspond to the energy splitting due to the coupling of two spatially separated Majorana bound states. The resulting Rabi oscillating frequencies from these two different resonant driving energies are identical for the Majorana bound states, while different for ordinary Andreev bound states. We further study a double-quantum-dot setup and find a nonlocal quantum correlation between them that is mediated by two Majorana bound states. This nonlocal correlation has the signature of additional resonant driving energies. Conclusion: Our method can be used to distinguish between Majorana bound states and Andreev bound states. It also gives a precise measurement of the energy splitting between two Majorana bound states.

scholarly journals SELECTION OF THE GROUND STATE FOR NONLINEAR SCHRÖDINGER EQUATIONS

2004 ◽  
Vol 16 (08) ◽  
pp. 977-1071 ◽  
Author(s):  
A. SOFFER ◽  
M. I. WEINSTEIN
Keyword(s):  
Excited State ◽  
Ground State ◽  
Bound States ◽  
Initial Conditions ◽  
Bound State ◽  
Large Time Behavior ◽  
Multiple Time ◽  
Time Behavior ◽  
Small Initial Data ◽  
Nonlinear Schrödinger

We prove for a class of nonlinear Schrödinger systems (NLS) having two nonlinear bound states that the (generic) large time behavior is characterized by decay of the excited state, asymptotic approach to the nonlinear ground state and dispersive radiation. Our analysis elucidates the mechanism through which initial conditions which are very near the excited state branch evolve into a (nonlinear) ground state, a phenomenon known as ground state selection. Key steps in the analysis are the introduction of a particular linearization and the derivation of a normal form which reflects the dynamics on all time scales and yields, in particular, nonlinear master equations. Then, a novel multiple time scale dynamic stability theory is developed. Consequently, we give a detailed description of the asymptotic behavior of the two bound state NLS for all small initial data. The methods are general and can be extended to treat NLS with more than two bound states and more general nonlinearities including those of Hartree–Fock type.

EXCHANGE FIELD EFFECT ON THE ANDREEV BOUND STATE STUDIED BY FERROMAGNET/HIGH Tc SUPERCONDUCTOR INTERFACE

2005 ◽  
Vol 19 (01n03) ◽  
pp. 495-497 ◽  
Author(s):  
K.-W. NG ◽  
MARIO FREAMAT
Keyword(s):  
Bound States ◽  
Bound State ◽  
Exchange Field ◽  
Zero Energy ◽  
S Wave ◽  
High Tc ◽  
Andreev Bound States ◽  
High Tc Superconductor ◽  
Energy Peak ◽  
Andreev Bound State

We have prepared Ag / BSCCO and Fe / Ag / BSCCO planar junctions to study the effect of Fe exchange field on the tunneling spectra. The junctions were constructed so that the tunneling direction is within the ab-plane, either along the maximum or minimum gap direction. Andreev bound states were observed as zero energy peak in the minimum gap direction. The exchange field caused major splitting of the zero energy peak, which did not occur in Ag / BSCCO junctions. We had detected a few percent (6 to 7%) of s-wave subcomponent at the interface in many of these junctions. This s-wave subcomponent had a Tc of about 20K.

BOUND STATES IN THE "PHYSICAL" QCD2

1990 ◽  
Vol 05 (13) ◽  
pp. 2605-2615
Author(s):  
FUAD M. SARADZHEV
Keyword(s):  
Bound States ◽  
Background Field ◽  
Bound State

Different variants of the "physical" QCD 2 are analyzed. The role of the chiral background field in the theory is stressed. A massive bound state creating operator in the massless "physical" QCD 2 is constructed.

scholarly journals Andreev bound states and their signatures

2018 ◽  
Vol 376 (2125) ◽  
pp. 20180140 ◽  
Author(s):  
J. A. Sauls
Keyword(s):  
State Formation ◽  
Quantum Coherence ◽  
Bound States ◽  
Andreev Reflection ◽  
Bound State ◽  
Unconventional Superconductivity ◽  
Excitation Energies ◽  
Andreev Bound States ◽  
Properties Of Superconductors ◽  
Andreev Scattering

Many of the properties of superconductors related to quantum coherence are revealed when the superconducting state is forced to vary in space in response to an external magnetic field, a proximity contact, an interface to a ferromagnet or to impurities embedded in the superconductor. Among the earliest examples is Andreev reflection of an electron into a retro-reflected hole at a normal-superconducting interface. In regions of strong inhomogeneity, multiple Andreev reflection leads to the formation of sub-gap states, Andreev bound states , with excitation energies below the superconducting gap. These states play a central role in our understanding of inhomogeneous superconductors. The discoveries of unconventional superconductivity in many classes of materials, advances in fabrication of superconducting/ferromagnetic hybrids and nanostructures for confining superfluid 3 He, combined with theoretical developments in topological quantum matter have dramatically expanded the significance of branch conversion scattering and Andreev bound state formation. This collection of articles highlights developments in inhomogeneous superconductivity, unconventional superconductivity and topological phases of superfluid 3 He, in which Andreev scattering and bound states underpin much of the physics of these systems. This article provides an introduction to the basic physics of Andreev scattering, bound-state formation and their signatures. The goal is both an introduction for interested readers who are not already experts in the field, and to highlight examples in which branch conversion scattering and Andreev bound states provide unique signatures in the transport properties of superconductors. This article is part of the theme issue ‘Andreev bound states’.

scholarly journals The exact solution of magnetic susceptibility for finite Ising ring with a magnetic impurity

2021 ◽  
Author(s):  
Dacheng Ma ◽  
Yan Qi ◽  
An Du
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
Ground State ◽  
Magnetic Impurity ◽  
Temperature Limit ◽  
Zero Temperature ◽  
Curie Constant ◽  
State Entropy ◽  
High Temperature Limit ◽  
Ground State Entropy

We connected the two ends of a finite spin-1/2 antiferromagnetic Ising chain with a magnetic impurity at one end to form a closed ring, and studied the magnetic susceptibility of it exactly by using the transfer matrix method. We calculated the magnetic susceptibility in the whole temperature range and gave the phase diagram at ground state of the system about the anisotropy of the impurity and strength of the connection exchange interaction for spin-1 and 3/2 impurities. We also gave the ground state entropy of system and derived the asymptotic expression of the magnetic susceptibility multiplied by temperature at zero temperature limit and high temperature limit. It is found that degenerate phase may exist in some parameter region at zero temperature for the spin number of system being odd, and the ground state entropy is ln⁡(2) in the nondegenerate phase and is dependent on the number of spin in the degenerate phase. The magnetic susceptibility of the system at low temperature exhibits ferromagnetic behavior, and the Curie constant is related to the spin configuration at ground state. When the ground state is nondegenerate, the Curie constant is equal to the square of the net spin, regardless of the parity of the number of the spin. When the number of spin is odd and the ground state is degenerate, the Curie constant may be related to the total number of spin. In high temperature limit, the magnetic susceptibility multiplied by temperature is related to the spin quantum number of impurity and the number of spin in the ring.

On noninertial effects inducing a confinement of a neutral particle to a hard-wall confining potential

Open Physics ◽  
2013 ◽  
Vol 11 (11) ◽  
Author(s):  
Knut Bakke
Keyword(s):  
Bound States ◽  
Magnetic Dipole Moment ◽  
Neutral Particle ◽  
Energy Levels ◽  
Bound State ◽  
Field Configuration ◽  
Hard Wall ◽  
Confining Potential ◽  
Noninertial Effects

AbstractIn this contribution, we discuss the confinement of a nonrelativistic spin-half neutral particle to a hard-wall confining potential induced by noninertial effects. We show that the geometry of the manifold plays the role of a hard-wall confining potential and yields bound state solutions. We also consider a neutral particle with a permanent magnetic dipole moment interacting with a field configuration induced by noninertial effects, and discuss the behaviour of the induced fields and obtain energy levels for bound states.

LOWEST-ORDER CONSTRAINED VARIATIONAL CALCULATIONS FOR TWO-DIMENSIONAL LIQUID 3He

2013 ◽  
Vol 12 (07) ◽  
pp. 1350061 ◽  
Author(s):  
G. H. BORDBAR ◽  
F. FATEMI ◽  
M. T. MOHAMADI SABET
Keyword(s):  
Total Energy ◽  
Cluster Expansion ◽  
Ground State ◽  
Bound State ◽  
Energy Functional ◽  
Two Dimensional ◽  
Zero Temperature ◽  
Lennard Jones ◽  
Pair Potentials ◽  
Variational Calculations

We have used the lowest-order constrained variational (LOCV) method based on the cluster expansion of the energy functional to calculate some ground state properties of two-dimensional liquid 3 He at zero temperature employing the Lennard-Jones and Aziz pair potentials. We have seen that the total energy increases by increasing density. It is shown that the two-dimensional liquid 3 He system has no self-bound state.

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