RbCl Quantum Research Articles

Magnetopolaron Energy Level in Parabolic Semi-exponential RbCl Quantum Wells in Magnetic Impurity Field

Magnetopolaron Energy Level in Parabolic Semi-exponential RbCl Quantum Wells in Magnetic Impurity Field

Temperature effect of strong-coupling polaron in RbCl quantum wells with double asymmetric confined potentials

In this study, the ground state properties of strong-coupling polaron in RbCl quantum wells (QWs) by using double asymmetric confined potential were theoretically investigated based on effective mass approximation. Ground state binding energy (GSBE), ground state energy (GSE), vibrational frequency (VF), and mean LO phonon number (MLOPN) were obtained as functions of asymmetric confinement potential parameters in QWs by using the unitary transformation method and linear combination operator. GSBE, GSE, VF and MLOPN were found to be increasing functions of asymmetric semi-exponential confinement potential (ASECP) parameter [Formula: see text] and decreasing functions of parameter [Formula: see text]. GSE was rapidly increased with the increase of confinement strength. GSBE, GSE, VF and MLOPN increase as the increasing (decreasing) of anisotropic parabolic confinement potential strength (confinement length). In addition, the temperature effect was evaluated by using quantum statistical theory. With the increase of temperature, GSE and GSBE decreased while VF and MNLOP increased.

Study of Extensive and Nonextensive Entropy of RbCl Quantum Well Qubit in an Asymmetric Gaussian Potential

We have presented extensive and nonextensive entropy of RbCl quantum well qubits (QWQ). To this end, we have considered an electron that is coupled to the LO-phonon in RbCl quantum well to determine the energy eigenvalues and eigenfunctions of the ground and first excited states of the system using the Pekar variational method. Here, we have used extensive and nonextensive entropies like Shannon and Tsallis to study decoherence of RbCl QWQ for different parameters. Our results show that the entropies have the oscillatory periodic evolution as a function of time due to the form of the confinement potential. According to the obtained results, we can see that the entropies oscillate under a sinusoidal envelope with enhancing the confinement parameters. These results may be very helpful in the transmission of information in the nanostructure.

The Optical Polaron Effect on the Coherent Time of a qubit in the RbCl Quantum Dot with Two-Dimensional Pseudoharmonic Potential

The effects of optical polarons on qubit coherence times in a RbCl quantum dot (QD) under a pseudoharmonic potential (PHP) are theoretically investigated using Fermi’s Golden Rule and Pekar type variational method (PTVM). From this, coherence time variations are analytically driven as a function of the chemical potential (CP) of two-dimensional electron gas (2DEG), polaron radius and PHP zero point, which are shown to have a significant impact. Our results provide a theoretical method for solving stability issues with qubits during quantum information.

Qubit coherence effects in a RbCl quantum well with asymmetric Gaussian confinement potential and applied electric field

We theoretically investigate the coherent time of a single qubit in a RbCl quantum well (QW) with asymmetric Gaussian confinement potential (AGCP) using the Pekar-type variational method. Additionally, we utilize Fermi’s golden rule to consider strong coupling between electrons and longitudinal optical phonons in the QW with an electric field applied. The results show that the coherence time changes with AGCP QW’s height, height of the QW, polaron radius and electric field. Moreover, we also show that the coherence time is minimized to $$ \tau = 412.0\;{\text{ps}} $$ in a confinement potential range $$ R = 0.19\;{\text{nm}} $$ . Thus we conclude that these tunable parameters of the QW are vital for adjusting the coherence time and deciding the stability of the qubit.

Cumulative effects of temperature, magnetic field and spin orbit interaction (SOI) on the properties of magnetopolaron in RbCl quantum well

In this work, we investigate the cumulative effects of temperature, spin orbit interaction (SOI) and the magnetic field on properties of the magnetopolaron in RbCl quantum well. The Ground state binding energy (GSBE) of the magnetopolaron in RbCl QW is evaluated using the Lee Low Pine Unitary transformation (LLPUT) and the combination operation method. Numerical results show that, in addition to temperature, the spin orbit interaction affects considerably the GSBE of the magnetopolaron. Also, the transition behavior at threshold values of the temperature as well as the cyclotron frequency is considered. This study reveals that the spin orbit interaction cannot be neglected during the investigation of the nanostructure system.

Study of RbCl quantum pseudo-dot qubits using Shannon and Laplace entropies

In this work, an electron was considered which is coupled to the LO-phonon in RbCl quantum pseudo-dot. The Pekar variational method was used to calculate the eigenenergies and eigenfunctions of the ground and the first-excited states of the system. Two different entropies were considered, the Shannon and Laplace, to study decoherence of RbCl pseudodot qubit for different parameters. According to the obtained results, it is found that the entropy has the oscillatory periodic evolution as a function of the time due to the form of the confinement potential. It is also found that the entropies oscillate under a sinusoidal envelope with increasing the confinement parameters.

Study of RbCl quantum pseudodot qubits by using of non-extensive entropies

In this work, an electron which is strongly coupled to the strong electron–phonon (e–p) in RbCl quantum pseudodot qubit is considered. First, we employ the Pekar variational method and obtain the eigenenergies and eigenfunctions of the ground and the first excited states of the system. Then, we have employed three different entropies such as Tsallis, Landsberg–Vedral, and Escort for the system subjected to an applied electric field. In this regard, we have studied the effect of polaronic radius, electric field, e–p coupling strength, and non-extensive parameter. It is found that the entropies oscillate with passing time. The entropies increase with enhancing electric field, e–p coupling strength and decrease with polaronic radius. The results show that the missing information in the RbCl pseudodot qubit can be controlled by changing the system parameters. According to the results, it is deduced that the entropy is an important quantity to display the total storage or missing information in a qubit.

The Effects of Electric Field on the Coherence Time of RbCl Quantum Pseudodot Qubit

We academically explore the properties of the coherence time (CT) of an electron powerful coupled to the phonons in a RbCl quantum pseudodot (QPD) qubit with an exterior electric field alongside the ρx direction. By employing the Pekar type variational method (PTVM) and the Fermi golden rule, the CT changes with the electric field, the chemical potential of the two-dimensional electron gas (CPTDEG), the zero point of the pseudoharmonic potential (ZPPHP) and the polaron radius is studied. The examined results indicate ① that the CT of RbCl QPD qubit decays with aggrandizing electric field, ② that the CT is a decreasing function of the CPTDEG, the ZPPHP and the polaron radius, ③ that here we can find that we can adjust the CT by changing the external electric field, the CPTDEG, the ZPPHP and the polaron radius.

The Effect of Coulomb Impurity Potential on the Coherence Time of RbCl Quantum Pseudodot Qubit

We have considered the pseudoharmonic potential (PHP) for a RbCl quantum pseudodot (QPD) qubit with a hydrogen-like impurity at the center. By employing the Pekar variational method and the Fermi Golden Rule, we study the properties of the coherence time of an electron strongly interacting with longitudinal optical phonon in a RbCl QPD qubit. The coherence time changing with the Coulombic impurity potential strength, the two-dimensional chemical potential of the electron gas, the PHP zero point and the polaron radius is theoretically investigated. The obtained results indicate that ① the coherence time of RbCl QPD qubit decreases with increasing Coulombic impurity potential strength, ② the coherence time is a decaying function of the two-dimensional chemical potential of the electron gas and the PHP zero point, ③ the smaller the polaron radius is, the smaller the coherence time is.

The ground-state lifetime of polaron in a two-dimensional quantum pseudodot system

We study the ground-state lifetime (GSL) of polaron in a two-dimensional RbCl quantum pseudodot (QPD) system by using a variational method of Pekar type (PTVM) and the quantum statistical theory. Considering the polaron effect, we derive the dependent relations of the temperature, the electric field, the chemical potential (CP) of the two-dimensional electron gas (TDEG), the polaron radius (PR) and the zero point (ZP) of the pseudoharmonic potential (PHP) on the GSL of polaron. The calculated results show that the GSL $$\tau$$ of polaron will decrease when the CP $$V_{0}$$ of the TDEG, the electric field and the PR $$R_{p}$$ increase, but will increase while the ZP $$r_{0}$$ of the PHP, the ground-state energy (GSE) and the temperature parameter $$\gamma$$ become larger, respectively. That means that by changing the electric field, the temperature, the PR, the CP of the TDEG and the ZP of the PHP, one can adjust the GSL of polaron, which may offer new insight into studying many related applications in quantum computation (QC) and control of electron transition.

Temperature and impurity effects on the vibrational frequency of the strongly-coupled polaron in asymmetrical semi-exponential RbCl quantum wells

Properties of the vibrational frequency (VF) and the ground state binding energy (GSBE) of the strong-coupled polaron in asymmetrical semi-exponential quantum wells (ASEQWs) with a hydrogen-like impurity (HLI) at the origin of coordinates are investigated. The temperature effects on the VF and the GSBE are taken into account by using the quantum statistics theory (QST). Based on the linear combination operation and LLP unitary transformation methods, the variations of the VF and the GSBE varying with the temperature and the strength of the Coulombic impurity potential (CIP) are discussed. We have found that the VF and the GSBE are increasing functions of the temperature and the CIP.

Effects of temperature and magnetic field on the spontaneous emission rate of polaron in a RbCl quantum rod qubit

By using the Lee-Low-Pines (LLP) unitary transformation and the Pekar type variational (PTV) method, we study the spontaneous emission rate (SER) of polaron in a RbCl quantum rod (QRD). Taking temperature and external magnetic field (EMF) influences into account, the dependence relations of the temperature, the intensity of coulomb bound potential (CBP), the external magnetic field (EMF) and the ellipsoidal aspect ratio (EAR) on the SER of polaron are derived. The calculated results show that the SER Γ of polaron will decrease when the temperature parameter γ, the intensity β of CBP and the EMF B become greater, respectively. And the SER Γ of polaron is a decreasing function of the EAR e' when e'<1.0, whereas it is an increasing function of the EAR e' when e'>1.0. By changing the temperature, the EMF, the intensity of CBP and the EAR, one can adjust the SER of polaron, which may offer new insight into the study many related applications in quantum computation (QC) and control of decoherence.

Temperature effect of a quantum pseudodot qubit

Considering a variational method of the Pekar type and the quantum statistics theory, the temperature effects on the probability density and the oscillating frequency of an electron-LO-phonon strongly coupling in a RbCl quantum pseudodot (QPD) are investigated. It is discovered that a qubit may be made up of a QPD two-level-system. Furthermore, when an electron locates in the superposition state of the ground and first excited states, the electron's probability density varies periodically with time and oscillates in the RbCl QPD with an independent period. The electron's probability density increases (decreases) with increasing temperature at low (high) temperature. At low (high) temperature, the oscillating frequency decreases (increases) with an increase of the temperature, the chemical potential of the two-dimensional electron gas and the zero point of the pseudoharmonic potential. The oscillating frequency is a decreasing function of the polaron radius.

Effect of electric field on RbCl quantum pseudodot qubit

By employing the variational method of Pekar type, we study the effects of electric field on RbCl quantum pseudodot (QPD) qubits. Our results confirm that (1) the electron oscillates in the RbCl QPD with a certain period; (2) the electron’s probability density is a raising function of electric field; (3) the oscillating frequency is an increasing one of the electric field and the two-dimensional electron gas chemical potential. Two ways are found for prolonging the lifetime of the qubit and suppressing the decoherence in the quantum information field.

The Effect of Temperature and Electric Field on a Quantum Pseudodot Qubit

The electron’s probability density (EPD) and the oscillating period (OP) of an electron confined by a three-dimensional RbCl quantum pseudodot (QPD) are studied. Calculations are performed by employing variational method of Pekar type (VMPT) and the quantum statistics theory (QST).The influences of the temperature and electric field on the EPD and the OP of the RbCl QPD qubit have been derived in detail. According to the obtained results, it is observed that the EPD and the OP increase (decrease) with raising temperature at lower (higher) temperature region. They are decaying functions of the electric field.

The effects of magnetic field and hydrogen-like impurity on RbCl quantum pseudodot qubit

By using a variational method of Pekar type, we investigate the effects of the hydrogen-like impurity and magnetic field on the electron’s probability density (PD) and oscillating frequency (OF) of a RbCl quantum pseudodot qubit. Numerical results indicate that (1) the PD oscillates periodically; (2) the crest of the PD will decrease with increasing the cyclotron frequencies and the Coulombic impurity potential strength; (3) as the cyclotron frequency of the magnetic field and the strength of the Coulombic impurity potential increases, PD’s peaks will occur more frequently; (4) besides, Figs. 1b and 2b clearly show that in a single period the PD will decrease with increasing the cyclotron frequency and the Coulombic impurity potential strength when \( t > 1.8\;\text{fs} \); whereas the changing law is just the opposite when \( t < 1.8\;\text{fs} \); (5) the OF is an aggrandizing function of the strength of the Coulombic impurity potential, whereas it is a decaying one of the cyclotron frequencies of the magnetic field. The coherence of qubit is crucial to the investigations of quantum information and quantum computation, where the electron’s PD, the OF and the coherence time are the physical quantities representing the properties of coherence. Our research results fine that by changing the cyclotron frequency of the magnetic field and the strength of the Coulombic impurity potential one can adjust the electron’s PD and the OF. Open image in new window Fig. 1 The PD \( \text{Q}\left( {r,t} \right) \) versus the time \( t \) and the cyclotron frequency of the magnetic field \( \omega_{c} \) with \( \text{V}_{0} = 10.0\,\text{meV, r}_{0} = 1.0\,\text{nm, }\beta \text{ = 1.0}\,\text{meV} \cdot \text{nm} \) and \( x = y = z = 1.0\,\text{nm} \) Open image in new window Fig. 2 The PD \( \text{Q}\left( {r,t} \right) \) versus the time \( t \) and strength of the Coulombic impurity potential \( \beta \) with \( \text{V}_{0} = 10.0\,\text{meV, r}_{0} = 1.0\,\text{nm,} \, \omega_{c} \text{ = 2.0}\, \times \text{10}^{13}\,\text{Hz} \) and \( x = y = z = 1.0\,\text{nm} \)

Effect of phonons on optical properties of RbCl quantum pseudodot qubits

In this work, an electron which is strongly coupled to the strong electron-longitudinal optical (LO) phonon in RbCl quantum pseudodot qubits is considered. First, we employ the Pekar variational method and obtain the eigenenergies and eigenfunctions of the ground and the first-excited states of the system. Then, we have studied optical properties of the system under strong electron-LO phonon coupling. In this regard, the refractive index changes and absorption coefficient of the system are obtained using compact-density-matrix approach and iterative method. It is found that the absorption coefficients show saturation in the presence of phonon effect. This behavior occurs at small quantum size and for different potential height. Our results show that both the structure parameters and phonon effect have a great effect on the total absorption and refractive index changes.

Application of non-extensive entropy to study of decoherence of RbCl quantum dot qubit: Tsallis entropy

In this work, an electron which is strongly coupled to the LO-phonon in triangular quantum dots with Coulomb impurity is considered. The eigenenergies and eigenfunctions of the ground and the first-excited states of the electron are obtained using the Pekar variational method. We have studied decoherence of RbCl quantum dot qubit using the non-extensive entropy (Tsallis entropy) for different values of Coulomb impurity parameter, polaronic radius and electron-LO phonon coupling strength. Numerical analysis shows that the entropy has the oscillatory periodic evolution as function of the time due to the triangular form of the confinement. It is found that entropy oscillates under a standing wave envelope with increasing the Coulomb impurity parameter, electron-LO phonon coupling strength and polaronic radius. With reducing the non-extensive parameter q, the entropy increases and thereby we can miss information about the system.

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.