Ground state energy, binding energy, and the impurity-specific heat of the Anderson–Holstein model

2015 ◽  
Vol 93 (10) ◽  
pp. 1024-1029 ◽  
Author(s):  
Ch. Narasimha Raju ◽  
Ashok Chatterjee
Keyword(s):  
Binding Energy ◽  
Specific Heat ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Electron Phonon Interaction ◽  
Holstein Model

A single-level Anderson–Holstein model is studied using the Lang–Firsov transformation followed by a zero-phonon averaging and a Green function method within the framework of a mean-field approximation. The ground state energy of the system, the binding energy between the impurity and conduction electrons, and the impurity–electron spectral function are calculated. The effect of the electron–phonon interaction on the local moment as well as on the specific heat of the impurity electron is explored in the anti-adiabatic regime.

BINDING ENERGY OF A BOUND POLARON IN THE FINITE PARABOLIC QUANTUM WELL

2001 ◽  
Vol 15 (20) ◽  
pp. 827-835 ◽  
Author(s):  
FENG-QI ZHAO ◽  
XI XIA LIANG
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Energy Levels ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Bound Polaron

We have studied the effect of the electron–phonon interaction on the energy levels of the bound polaron and calculated the ground-state energy, the binding energy of the ground state, and the 1 s → 2 p ± transition energy in the GaAs/Al x Ga 1-x As parabolic quantum well (PQW) structure by using a modified Lee–Low–Pines (LLP) variational method. The numerical results are given and discussed. It is found that the contribution of electron–phonon interaction to the ground-state energy and the binding energy is obvious, especially in large well-width PQWs. The electron–phonon interaction should not be neglected.

scholarly journals Ground-state energy of a Richardson-Gaudin integrable BCS model

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Yibing Shen ◽  
Phillip Isaac ◽  
Jon Links
Keyword(s):  
Integral Equation ◽  
Ground State Energy ◽  
Ground State ◽  
Continuum Limit ◽  
State Energy ◽  
Mean Field ◽  
Bcs Model ◽  
Energy Expression ◽  
The Continuum

We investigate the ground-state energy of a Richardson-Gaudin integrable BCS model, generalizing the closed and open p+ip models. The Hamiltonian supports a family of mutually commuting conserved operators satisfying quadratic relations. From the eigenvalues of the conserved operators we derive, in the continuum limit, an integral equation for which a solution corresponding to the ground state is established. The energy expression from this solution agrees with the BCS mean-field result.

Ground-State Energy of an Exciton

1973 ◽  
Vol 51 (10) ◽  
pp. 1104-1108
Author(s):  
M. H. Hawton ◽  
P. K. Dubey ◽  
V. V. Paranjape
Keyword(s):  
Binding Energy ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Conventional Approach ◽  
Phonon Energy ◽  
Energy Ratio

We propose a method which differs from the conventional approach used by several authors for calculating the shift in the ground-state energy, E1s, of an exciton. Our approach allows us to obtain the shift for values of binding-energy-to-phonon-energy ratio, β2, which are not restricted to the range [Formula: see text], as is the case with earlier approaches. In the limit of small β, our result for E1s reduces to the expression derived by earlier authors.

THE INFLUENCE OF ELECTRIC FIELD ON THE GROUND-STATE LIFETIME OF POLARON IN A PARABOLIC QUANTUM DOT

2011 ◽  
Vol 25 (03) ◽  
pp. 203-210
Author(s):  
WEI-PING LI ◽  
JI-WEN YIN ◽  
YI-FU YU ◽  
JING-LIN XIAO
Keyword(s):  
Quantum Dot ◽  
Electric Field ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Electron Phonon Interaction ◽  
Parabolic Quantum Dot

The ground-state energy of polaron was obtained with strong electron-LO-phonon coupling by using a variational method of the Pekar type in a parabolic quantum dot (QD). Quantum transition occurs in the quantum system due to the electron-phonon interaction and the influence of temperature. That is the polaron transition from the ground-state to the first-excited state after absorbing a LO-phonon and it causes the changing of the polaron lifetime. Numerical calculations are performed and the results illustrate the relations of the ground-state lifetime of the polaron on the ground-state energy of polaron, the electric field strength, the temperature, the electron-LO-phonon coupling strength and the confinement length of the quantum dot.

Effects of Temperature and Hydrogen-Like Impurity on the Vibrational Frequency of the Polaron in RbCl Parabolic Quantum Dots

NANO ◽  
2016 ◽  
Vol 11 (03) ◽  
pp. 1650029 ◽  
Author(s):  
Wei Xiao ◽  
Jing-Lin Xiao
Keyword(s):  
Binding Energy ◽  
Ground State Energy ◽  
Ground State ◽  
Vibrational Frequency ◽  
State Energy ◽  
Impurity Potential ◽  
Ground State Binding Energy ◽  
Effects Of Temperature ◽  
Increasing Function ◽  
Coulombic Impurity Potential

The properties of an electron strongly coupled to longitudinal optical (LO) phonon in RbCl parabolic quantum dot (PQD) with a hydrogen-like impurity at the center were investigated at a finite temperature. We have obtained the vibrational frequency of a strong-coupling polaron in RbCl PQD by using linear combination operator method. We then calculate the effects of temperature, the Coulombic impurity potential and the effective confinement strength on the vibrational frequency by using unitary transformation and the quantum statistics theory methods. The influences of the temperature, the Coulombic impurity potential and the effective confinement strength on the ground state energy and the ground state binding energy are also analyzed. The strengths of these quantities increase with raising temperature. The vibrational frequency is an increasing function of the Coulombic impurity potential and the effective confinement strength. The ground state energy is an increasing function of the effective confinement strength, whereas it is a decreasing one of the Coulombic impurity potential. The ground state binding energy is an increasing function of the Coulombic impurity potential, whereas it is a decayed one of the effective confinement strength.

Unraveling the origin of higher success probabilities in quantum annealing versus semi-classical annealing

2022 ◽  
Author(s):  
Elias Andre Starchl ◽  
Helmut Ritsch
Keyword(s):  
Hilbert Space ◽  
Ground State ◽  
Mean Field ◽  
Optimal Solution ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Quantum Model ◽  
Local Defect ◽  
Quantum Annealing ◽  
Full Quantum

Abstract Quantum annealing aims at finding optimal solutions to complex optimization problems using a suitable quantum many body Hamiltonian encoding the solution in its ground state. To find the solution one typically evolves the ground state of a soluble, simple initial Hamiltonian adiabatically to the ground state of the designated final Hamiltonian. Here we explore whether and when a full quantum representation of the dynamics leads to higher probability to end up in the desired ground when compared to a classical mean field approximation. As simple but nontrivial example we target the ground state of interacting bosons trapped in a tight binding lattice with small local defect by turning on long range interactions. Already two atoms in four sites interacting via two cavity modes prove complex enough to exhibit significant differences between the full quantum model and a mean field approximation for the cavity fields mediating the interactions. We find a large parameter region of highly successful quantum annealing, where the semi-classical approach largely fails. Here we see strong evidence for the importance of entanglement to end close to the optimal solution. The quantum model also reduces the minimal time for a high target occupation probability. Surprisingly, in contrast to naive expectations that enlarging the Hilbert space is beneficial, different numerical cut-offs of the Hilbert space reveal an improved performance for lower cut-offs, i.e. an nonphysical reduced Hilbert space, for short simulation times. Hence a less faithful representation of the full quantum dynamics sometimes creates a higher numerical success probability in even shorter time. However, a sufficiently high cut-off proves relevant to obtain near perfect fidelity for long simulations times in a single run. Overall our results exhibit a clear improvement to find the optimal solution based on a quantum model versus simulations based on a classical field approximation.

KINETIC ENERGY AND PHASE SEPARATION IN A DOPED ANTIFERROMAGNET

1995 ◽  
Vol 09 (24) ◽  
pp. 1623-1629 ◽  
Author(s):  
XIN XU ◽  
YUN SONG ◽  
SHIPING FENG
Keyword(s):  
Phase Separation ◽  
Kinetic Energy ◽  
Ground State ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Numerical Result ◽  
The Mean ◽  
State Kinetic

The ground-state kinetic energy of the t-J model is studied within the mean field approximation by using the fermion-spin transformation, the results show that the mean field ground-state kinetic energy is close to the numerical result at under dopings, and roughly consistent with the numerical result at optimal dopings. It is also shown that the frustration term J′ is favourable to diminish the range of the phase seperation in the t-J model.

On ℓp-Gaussian–Grothendieck Problem

2021 ◽  
Author(s):  
Wei-Kuo Chen ◽  
Arnab Sen
Keyword(s):  
Spin Glass ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Mean Field ◽  
Stability Estimates ◽  
Spin Glass Model ◽  
Maximum Value ◽  
Glass Model ◽  
Gaussian Orthogonal Ensemble

Abstract For $p\geq 1$ and $(g_{ij})_{1\leq i,j\leq n}$ being a matrix of i.i.d. standard Gaussian entries, we study the $n$-limit of the $\ell _p$-Gaussian–Grothendieck problem defined as $$\begin{align*} & \max\Bigl\{\sum_{i,j=1}^n g_{ij}x_ix_j: x\in \mathbb{R}^n,\sum_{i=1}^n |x_i|^p=1\Bigr\}. \end{align*}$$The case $p=2$ corresponds to the top eigenvalue of the Gaussian orthogonal ensemble; when $p=\infty $, the maximum value is essentially the ground state energy of the Sherrington–Kirkpatrick mean-field spin glass model and its limit can be expressed by the famous Parisi formula. In the present work, we focus on the cases $1\leq p<2$ and $2<p<\infty .$ For the former, we compute the limit of the $\ell _p$-Gaussian–Grothendieck problem and investigate the structure of the set of all near optimizers along with stability estimates. In the latter case, we show that this problem admits a Parisi-type variational representation and the corresponding optimizer is weakly delocalized in the sense that its entries vanish uniformly in a polynomial order of $n^{-1}$.

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