Ground-state Energy Of Polaron Research Articles

The influences of parabolic potential and magnetism on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells

In this research, the effects of magnetism and parabolic potential on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells (AGQWs) were investigated. To do so, the following six parameters were studied, temperature, AGQW barrier height, Gaussian confinement potential (GCP) width, confinement strengths along the directions of [Formula: see text] and [Formula: see text], as well as magnetic field cyclotron frequency. The relationships among frequency oscillation, AGQW parameters and polaron ground state energy in RbCl crystal were studied based on linear combination operator and Lee–Low–Pines unitary transformation. It was concluded that ground state energy absolute value was decreased by increasing GCP width and temperature, and increased with the increase of confinement strength along [Formula: see text] and [Formula: see text] directions, cyclotron frequency of magnetic field and barrier height of AGQW. It was also found that vibrational frequency was increased by enhancing confinement strengths along the directions of [Formula: see text] and [Formula: see text], magnetic field cyclotron frequencies, barrier height AGQW and temperature and decreased with the increase of GCP width.

Quantum Behavior of a Heavy Impurity Strongly Coupled to a Bose Gas.

We investigate the problem of an infinitely heavy impurity interacting with a dilute Bose gas at zero temperature. When the impurity-boson interactions are short-ranged, we show that boson-boson interactions induce a quantum blockade effect, where a single boson can effectively block or screen the impurity potential. Since this behavior depends on the quantum granular nature of the Bose gas, it cannot be captured within a standard classical-field description. Using a combination of exact quantum MonteCarlo methods and a truncated basis approach, we show how the quantum correlations between bosons lead to universal few-body bound states and a logarithmically slow dependence of the polaron ground-state energy on the boson-boson scattering length. Moreover, we expose the link between the polaron energy and the spatial structure of the quantum correlations, spanning the infrared to ultraviolet physics.

Temperature Dependence of the Ground State of Impurity Bound Magneto-Acoustic Polarons in Monolayer Graphene

The properties of impurity bound magneto-acoustic strong-coupling polarons in monolayer graphene are examined. The energies of the ground state of the impurity bound magneto-acoustic polaron were obtained by using the linear combination operator and the well-known Lee-Low-Pines transformation methods. By employing the quantum statistics theory, the temperature effects on the ground state energy of magneto-acoustic polarons in monolayer graphene were calculated. The results of the numerical model with regards to the temperature, Coulombic impurity potential, Debye cut-off wavenumber and magnetic field strength are discussed, and it was revealed that the tuning of these factors can offer a way of adjusting the ground state energy of the magneto-acoustic polaron.

Effect of the anisotropic parabolic potential on the polaron’s properties in asymmetric Gaussian quantum wells

In the current study, the linear combination operator (LCO) and Lee–Low–Pines unitary transformation (LLPUT) are adopted to verify the effect of the anisotropic parabolic potential (APP) on the polaron’s properties in the asymmetric Gaussian quantum well (AGQW). Relations of the vibrational frequency (VF) and the ground state energy (GSE) of weak coupling polaron in the AGQW for GaAs crystal varying with the effective confinement strengths of the APP, the barrier height, and range of the asymmetric Gaussian confinement potential (AGCP) are derived. The numerical calculated results illustrate that the GSE and VF of the weak coupling polaron in the AGQW can increase according to the effective confinement strengths’ growth for given values of the barrier height and range of the AGCP. They will increase by increasing the barrier height of the AGCP. However, they are decreasing functions of the range of the AGCP for the determined values of the effective confinement strengths and the barrier height of the AGCP.

Effects of an anisotropic parabolic potential and Coulomb's impurity potential on the energy characteristics of asymmetrical semi-exponential CsI quantum wells

Because of its unique optoelectronic properties, people have studied the characteristics of polarons in various quantum well (QW) models. Among them, the asymmetrical semi-exponential QW (ASEQW) is a new model for studying the structure of QWs in recent years. It is of great significance to study the influences of the impurity and anisotropic parabolic confinement potential (APCP) on the crystal’s properties, because some of the impurities, usually regarded as Coulomb’s impurity potential (CIP), will exist in the crystal more or less, and the APCP has flexible adjustment parameters. However, the energy characteristics of the ASEQW under the combined actions of impurities and APCP have not been studied, which is the motivation of this paper. Using the linear combination operation and Lee–Low–Pines unitary transformation methods, we investigate the vibrational frequency and the ground state energy of the strong coupling polaron in an ASEQW with the influences of the CIP at the origin of coordinates and APCP, and make a comparison between our results and previous literature’s. Our numerical results about the energy properties in the ASEQW influenced by the CIP and APCP may have important significances for experimental design and device preparation.

The Properties of the Polarons’ Ground State in Coupling Spherical Quantum Dots

Investigations on the properties of polarons in coupling quantum dots (QDs) are useful for the designs of quantum devices and applications of QDs. Based on accurately solving the time-independent Schrodinger equation, the famous Lee-Low-Pines unitary transformation (LLPUT) and variation methods, we have obtained the ground state energy of polarons in two spherical quantum dots (TSQD) with Coulomb interaction. The numerical results show that Coulomb interaction energy, electronic kinetic energy, induced potential and the ground state energy all decrease with increasing the interval of spherical centers or radius of quantum dot (QD).

Influences of the Temperature on the Ground State of the Coupling Polaron in an Asymmetric Quantum Pseudodot Under the External Magnetic Field

We studied that the influences of the temperature on the ground state energy of the coupling polaron in an asymmetric quantum pseudodot (QPD) under the external magnetic field by using the quantum statistical theory (QST) and the variational method of the Pekar-type (VMPT). And the relations between the ground state energy and the external magnetic field, the chemical potential of the two-dimensional electron gas, the pseudoharmonic potential (PHP) zero point, the coupling strength and the effective confinement lengths are discussed. The results of our study have shown that the ground state energy firstly declines and then rises as the temperature is increased from a low value. We also find that the ground state energy rises with the enhancing external magnetic field and the chemical potential of the two-dimensional electron gas. And the ground state energy declines firstly and then reinforces as the PHP zero point is enhanced. What’s more, the ground state energy is reductive function of the coupling strength and the effective confinement lengths.

Effects of Temperature on the Ground State Energy of the Strong Coupling Polaron in a RbCl Asymmetrical Semi-Exponential Quantum Well

In this article, temperature effects on strong coupling polaron in a RbCl asymmetrical semi-exponential quantum well (ASEQW) are studied by applying the quantum statistical theory (QST). Based on the well-known LLP unitary transformation and linear combination operation (LCO) methods, we have derived the ground state energy and the mean phonon number of strong coupling polaron in the ASEQW. According to the obtained results, ground state energy decreases with increasing temperature, whereas mean phonon number increases by increasing temperature. The ground state energy and mean phonon number are decaying functions with raising parameter $\sigma $ , whereas they are enhancing ones with lifting parameter $U_{0}$ .

Asymptotic dependence of Gross–Tulub polaron ground-state energy in the strong coupling region

Asymptotic dependence of Gross–Tulub polaron ground-state energy in the strong coupling region

Polaron Rashba Effect in a Parabolic Quantum Well

The polaron Rashba effect in a parabolic quantum well is studied using LLP variational method. The expression of polaron ground state energy is derived and the relations between the ground state energy with the half well-width and wave vector are discussed, respectively. The results show that the ground state energy is a decreasing function of the half well-width and is an increasing function of the wave vector. Due to the Rashba effect, the ground state energy of zero spin–orbit splits into two branches.

The effects of temperature and electric field on the properties of the polaron in a RbCl quantum pseudodot

The polaron ground state energy and the mean number of LO phonons are obtained by using variational method of Pekar type on the condition of strong electron-LO phonon coupling in a RbCl quantum pseudodot under applied electric field. The dependences of the polaron ground state energy and the mean number of LO phonons on the temperature and the electric field are derived by employing quantum statistical theory. It is found that the absolute value of the ground state energy increases when the temperature is increased at lower temperature regimes, and decreases when the temperature increases at higher temperature regimes. The mean number of LO phonons aggrandizes with increasing temperature. The absolute value of the ground state energy is a raising function of the electric field, whereas the mean number of LO phonons is a decaying one of it.

Temperature Effect of Hydrogen-Like Impurity on the Ground State Energy of Strong Coupling Polaron in a RbCl Quantum Pseudodot

We study the ground state energy and the mean number of LO phonons of the strong-coupling polaron in a RbCl quantum pseudodot (QPD) with hydrogen-like impurity at the center. The variations of the ground state energy and the mean number of LO phonons with the temperature and the strength of the Coulombic impurity potential are obtained by employing the variational method of Pekar type and the quantum statistical theory (VMPTQST). Our numerical results have displayed that Open image in new window the absolute value of the ground state energy increases (decreases) when the temperature increases at lower (higher) temperature regime, Open image in new window the mean number of the LO phonons increases with increasing temperature, Open image in new window the absolute value of ground state energy and the mean number of LO phonons are increasing functions of the strength of the Coulombic impurity potential.

Influences of RSO interaction and LO phonon effect on the spin polarization state energy of polaron in a quantum rod

On the basis of Lee-Low-Pines unitary transformation, the influences of Rashba spin–orbit (RSO) coupling energy and Zeeman splitting energy on the ground-state energy of polaron in a quantum rod (QRD) have been studied by using a variational method of Pekar type. Taking the RSO interaction and the Zeeman splitting into account, we derive the variational relations of the absolute ratios \( \zeta_{1} \) and \( \zeta_{2} \) of the RSO coupling energy and the Zeeman splitting energy to the ground-state energy of polaron with the transverse confinement radius (TCR) and the longitudinal confinement length (LCL) of QRD, as well as and the magnetic field adjusting length (MFAL). The results show that the absolute ratios \( \zeta_{1} \) and \( \zeta_{2} \) will increase when the TCR and the LCL become larger, but will slowly decrease while the MFAL and the aspect ratio of the ellipsoid \( \delta \) increase, respectively. The above results can be attributed to the spin effects and interesting quantum size confining.

Influence of Rashba spin-orbit interaction and Zeeman splitting on the ground state energy of polaron in an asymmetric quantum dot

On the basis of Lee–Low–Pines unitary transformation, the influence of Rashba spin-orbit (RSO) interaction and Zeeman splitting on the ground state energy of polaron in an asymmetric quantum dot (AQD) is studied by using the variational method of Pekar type. The variations of the absolute ratios of the Zeeman splitting energy and the RSO coupling energy to the ground state energy of polaron with the transverse confinement length (TCL) and the longitudinal confinement length (LCL) of AQD and the magnetic field adjusting length (MFAL) are derived when the RSO interaction and the Zeeman splitting are taken into account. We find the influences of the Zeeman splitting energy and the RSO coupling energy on the ground state energy of a polaron are more dominant when the values of the TCL and the LCL are small. The absolute ratio of the Zeeman splitting energy to the ground state energy rapidly decreases with increasing the MFAL and the absolute ratio of the RSO coupling energy to the ground state energy slowly decreases with increase in MFAL when [Formula: see text], whereas the absolute ratio of the RSO coupling energy to the ground state energy rapidly increases with increase in MFAL when [Formula: see text]. The above results can be attributed to the interesting quantum size confining and spin effects.

Electric and magnetic optical polaron in quantum dot—Part 1: strong coupling

We investigated the influence of electric field and magnetic field on the ground state energy of polaron in spherical semiconductor quantum dot (QD) using a modified Lee Low Pines (LLP) method. The numerical results show the increase of the ground state energy with the increase of the electric field and the decreasing with the magnetic field. The modulation of the electric field, magnetic field and the confinement lengths lead to the control of the decoherence of the system.

Excitonic polarons in low-dimensional transition metal dichalcogenides

We examine the excitonic polaron properties of common monolayer transition metal dichalcogenides (MoS2, MoSe2, WS2 and WSe2). The excitonic polaron is formed when excitons interact with acoustic or optical phonons via coupling to the deformation potentials associated with the conduction and valence bands. A unitary transformation which performs an approximate diagonalization of the exciton–phonon operator is used to evaluate the ground state energy of the excitonic polaron. We derive analytical expressions of the changes in the excitonic polaron energy and mass at small exciton wavevectors involving the deformation potential due to optical phonons. The polaronic effect of the monolayer transition metal dichalcogenides is examined by comparing changes in the energy gap shift and effective masses based on known deformation potential constants for carrier–phonon interactions. Our results indicate the occurrence of comparable energy shifts when the ground state exciton interacts with optical or acoustic phonons. We extend our calculations to explore the influence of exciton–lattice interactions on the binding energies and the self-trapping of excitons in two-dimensional layers of transition metal dichalcogenides.

Bound polaron in a quantum pseudodot under Rashba effect

In the present work, the influence of Rashba effect on bound polaron in a quantum pseudodot is studied. Using the Lee–Low–Pines unitary transformation method and the Pekar type variational procedure, we have derived an expression for the bound polaron ground state energy. The ground state energy as functions of the wave vector, the electron–phonon coupling strength, and quantum confinement size is obtained by considering different Coulomb bound potentials. It is found that (i) the ground state energy is decreased with raising the Coulomb bound potential, the electron–phonon coupling strength, and quantum confinement size. (ii) The ground state energy increases when the wave vector is increasing. (iii) The ground state energy splits into two branches (spin-up and spin-down) due to the Rashba effect.

The effect of the Rashba spin-orbit coupling on the ground-state energy of polaron in a parabolic quantum dot

We using a variational method of Pekar type to study the effect of the spin on the ground-state energy of a polaron in a parabolic quantum dot (QD). Under the influences of the Rashba spin-orbit (RSO) coupling and the Zeeman energy level splitting are taken into account, the expression of the ground-state energy of a polaron as functions of the radius of QD, the coupling constant and the magnetic field adjusting length was derived. We found that the ground-state energy and the spin-up (spin-down) ground-state splitting energy decrease with increasing the radius of QD. The absolute ratios of the Zeeman energy and RSO coupling energy to the ground-state energy are a decreasing function of the magnetic field adjusting length, respectively. The above results can be attributed to the interesting quantum size confining and spin effects.

Modified Lee-Low-Pines Polaron in Spherical Quantum Dot in an Electric Field

In this paper, we investigated the influence of e lectric field on the ground state energy of polaron in spherical semiconductor quantum dot (QD) using modified Lee Low Pines (LLP) method. The numerical results show the increase of the ground state energy with the increase of the electric field and the co nfinement lengths. The modulation of the electric and the confinement len gths lead to the control of the decoherence of the system.

Energy Levels of Weak Coupling Magneto-Optical Polaron and Temperature Effect in Spherical Quantum Dot

In this paper, we investigate the influence of the magnetic field and the temperature on the ground state energy of a weak coupling polaron in a spherical semiconductor quantum dot (QD) using the modified LLP method. The ground state energy of a weak coupling magneto-optical polaron is split into sub-energy levels and there is the degeneracy of the energy levels. It is also seen that the split energies are increasing functions of the electron-phonon coupling constant and decreasing functions of the magnetic field while the temperature is an increasing function of the cyclotron frequency for very low values of the longitudinal confinement length.