A Hamiltonian which represents the interaction between a single Cooper-pair box and two quantized electromagnetic fields is considered in order to find new ways for quantum information. The wave function in Schrodinge...A Hamiltonian which represents the interaction between a single Cooper-pair box and two quantized electromagnetic fields is considered in order to find new ways for quantum information. The wave function in Schrodinger picture is obtained. The evolution of the entropy of the box as a function of the scaled time is ploted to measure the entanglement between the box and the fields. It is found that the entanglement is sensitive to the detuning between the Josephson energy and the fields frequency, increasing the detuning can decrease the entanglement.展开更多
The conduction of a single-wall carbon nanotube depends on the pitch. If there are an integral number of carbon hexagons per pitch, then the system is periodic along the tube axis and allows “holes” (not “electrons...The conduction of a single-wall carbon nanotube depends on the pitch. If there are an integral number of carbon hexagons per pitch, then the system is periodic along the tube axis and allows “holes” (not “electrons”) to move inside the tube. This case accounts for a semiconducting behavior with the activation energy of the order of around 3 meV. There is a distribution of the activation energy since the pitch and the circumference can vary. Otherwise nanotubes show metallic behaviors (significantly higher conductivity). “Electrons” and “holes” can move in the graphene wall (two dimensions). The conduction in the wall is the same as in graphene if the finiteness of the circumference is disregarded. Cooper pairs formed by the phonon exchange attraction moving in the wall is shown to generate a temperature-independent conduction at low temperature (3 - 20 K).展开更多
The quantum dynamics of a charge qubit, which makes up of a single-Cooper-pair box, are explored. The Cooper-pair box is irradiated by a squeezed field in an ideal one-mode cavity. By the result of the Schrodinger equ...The quantum dynamics of a charge qubit, which makes up of a single-Cooper-pair box, are explored. The Cooper-pair box is irradiated by a squeezed field in an ideal one-mode cavity. By the result of the Schrodinger equation, the Cooper pairs number 〈N〉 is conveniently obtained. Then it is proved that the oscillations of the Cooper-pair number 〈N〉 are decreasing with the increasing squeezing parameter of the squeezed field.展开更多
A Cooper-pair box biased by a classical voltage and also irradiated by a squeezed state field is considered in order to find new ways to quantum communication and calculation. The quantum dynamics of the Cooper-pair b...A Cooper-pair box biased by a classical voltage and also irradiated by a squeezed state field is considered in order to find new ways to quantum communication and calculation. The quantum dynamics of the Cooper-pair box and the entanglement which is the core theoretics of quantum communication and calculation is investigated in this system, which is related to the squeezing parameter of the squeezed state, A model of Hamiltonian which represents the interaction between box and quantum field is introduced. Finally, the relationship between the entanglement and the squeezing parameter of the squeezed state is demonstrated.展开更多
This paper examines the quantization of mesoscopic circuit including Josephson junctions. Following Feynman＇s assumption, via the Hamilton dynamic approach and by virtue of the entangled state representation, it cons...This paper examines the quantization of mesoscopic circuit including Josephson junctions. Following Feynman＇s assumption, via the Hamilton dynamic approach and by virtue of the entangled state representation, it constructs Hamiltonian operator for the double-Josephson-junction mesoscopic circuit coupled by a capacitor. Then it uses the Heisenberg equation of motion to derive the induction voltage across each Josephson junction. The result manifestly shows how the voltage is affected by the capacitance coupling.展开更多
The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superco...The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superconductivity.The surrounding area of the electronic tornado is expanding,which is the basis of the Meissner effect,and the center is contracting,which is the basis of the pinning force.When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force,the electrons form a Cooper pair and release dark energy into virtual space-time.When the dark energy increases to a certain extent,the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave,which fluctuates freely in the superconducting material,which is the basis for the superconducting resistance to be zero.This is similar to the principle of a hot air balloon.The virtual space-time is hot air and the electron pair is a hot air balloon device.Conductor electrons are free and easy to emit dark energy,resulting in insufficient dark energy,and it is not easy to form electron-pair virtual space-time waves,so the superconducting critical temperature is very low.This is because the emission coefficient of the conductor is too high.Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves.Therefore,the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator.The solution of the Qi-space-time wave equation,that is,the coherence coefficient,is an important factor in superconductivity.In addition,the conditions under which tornadoes form are also an important basis for superconductivity.Finally,it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.展开更多
The dynamics of the skew information (SI) is investigated for a single Cooper Pair Box (CPB) interacting with a single cavity field. By suitably choosing the system parameters and precisely controlling the dynamics, n...The dynamics of the skew information (SI) is investigated for a single Cooper Pair Box (CPB) interacting with a single cavity field. By suitably choosing the system parameters and precisely controlling the dynamics, novel connection is found between the SI and entanglement generation. It is shown that SI can be increased and reach its maximum value either by increasing the number of photons inside the cavity or considering the far off-resonant case.The number of oscillations of SI is increased by decreasing this ratio between the Josephson junction capacity and the gate capacity. This leads to significant improvement of the travelling time between the maximum and minimum values.展开更多
We calculate the absorption cross-section for photon by a hydrogen 2s atom using the quantum-classical approximation for the total photo cross-section of many electron atoms. With the application of the first-order te...We calculate the absorption cross-section for photon by a hydrogen 2s atom using the quantum-classical approximation for the total photo cross-section of many electron atoms. With the application of the first-order term of the Baker Hausdorf expansion, the absorption cross-section for the hydrogen 2s atom decreases to a minimum, the Cooper paJr minimum, at low photon energy. Such a minimum is absent in the exact absorption cross-section for photon by a hydrogen 2s atom. We have extended the calculation for the absorption cross-section of the hydrogen 2s atom using the quantum-classical approximation for the total photo cross-section of many electron to include the second-order term of the Baker-Hausdorf expansion and observed a great reduction in the dip associated with the Cooper pair minimum at the zero crossing.展开更多
Individual metallic single-wall carbon nanotubes show unusual non-Ohmic transport behaviors at low and high bias fields. For low-resistance contact samples, the differential conductance increases with increasing bias,...Individual metallic single-wall carbon nanotubes show unusual non-Ohmic transport behaviors at low and high bias fields. For low-resistance contact samples, the differential conductance increases with increasing bias, reaching a maximum at ~100 mV. As the bias increases further, drops dramatically [1]. The higher the bias, the system behaves in a more normal (Ohmic) manner. This low-bias anomaly is temperature-dependent (50 - 150 K). We propose a new interpretation. Supercurrents run in the graphene wall below ~150 K. The normal hole currents run on the outer surface of the wall, which are subject to the scattering by phonons and impurities. The currents along the tube length generate circulating magnetic fields and eventually destroy the supercurrent in the wall at high enough bias, and restore the Ohmic behavior. If the prevalent ballistic electron model is adopted, then the temperature-dependent scattering effects cannot be discussed. For the high bias (0.3 - 5 V), (a) the I-V curves are temperature-independent (4 - 150 K), and (b) the currents (magnitudes) saturate. The behavior (a) arises from the fact that the neutral supercurrent below the critical temperature is not accelerated by the electric field. The behavior (b) is caused by the limitation of the number of quantum-states for the “holes” running outside of the tube.展开更多
The pairon field operator ψ(r,t) evolves, following Heisenberg’s equation of motion. If the Hamiltonian H contains a condensation energy α0(<0) and a repulsive point-like interparticle interaction , , the evolut...The pairon field operator ψ(r,t) evolves, following Heisenberg’s equation of motion. If the Hamiltonian H contains a condensation energy α0(<0) and a repulsive point-like interparticle interaction , , the evolution equation for ψ is non-linear, from which we derive the Ginzburg-Landau (GL) equation: for the GL wave function where σdenotes the state of the condensed Cooper pairs (pairons), and n the pairon density operator (u and are kind of square root density operators). The GL equation with holds for all temperatures (T) below the critical temperature Tc, where εg(T) is the T-dependent pairon energy gap. Its solution yields the condensed pairon density . The T-dependence of the expansion parameters near Tc obtained by GL: constant is confirmed.展开更多
文摘A Hamiltonian which represents the interaction between a single Cooper-pair box and two quantized electromagnetic fields is considered in order to find new ways for quantum information. The wave function in Schrodinger picture is obtained. The evolution of the entropy of the box as a function of the scaled time is ploted to measure the entanglement between the box and the fields. It is found that the entanglement is sensitive to the detuning between the Josephson energy and the fields frequency, increasing the detuning can decrease the entanglement.
文摘The conduction of a single-wall carbon nanotube depends on the pitch. If there are an integral number of carbon hexagons per pitch, then the system is periodic along the tube axis and allows “holes” (not “electrons”) to move inside the tube. This case accounts for a semiconducting behavior with the activation energy of the order of around 3 meV. There is a distribution of the activation energy since the pitch and the circumference can vary. Otherwise nanotubes show metallic behaviors (significantly higher conductivity). “Electrons” and “holes” can move in the graphene wall (two dimensions). The conduction in the wall is the same as in graphene if the finiteness of the circumference is disregarded. Cooper pairs formed by the phonon exchange attraction moving in the wall is shown to generate a temperature-independent conduction at low temperature (3 - 20 K).
文摘The quantum dynamics of a charge qubit, which makes up of a single-Cooper-pair box, are explored. The Cooper-pair box is irradiated by a squeezed field in an ideal one-mode cavity. By the result of the Schrodinger equation, the Cooper pairs number 〈N〉 is conveniently obtained. Then it is proved that the oscillations of the Cooper-pair number 〈N〉 are decreasing with the increasing squeezing parameter of the squeezed field.
文摘A Cooper-pair box biased by a classical voltage and also irradiated by a squeezed state field is considered in order to find new ways to quantum communication and calculation. The quantum dynamics of the Cooper-pair box and the entanglement which is the core theoretics of quantum communication and calculation is investigated in this system, which is related to the squeezing parameter of the squeezed state, A model of Hamiltonian which represents the interaction between box and quantum field is introduced. Finally, the relationship between the entanglement and the squeezing parameter of the squeezed state is demonstrated.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574060)the Natural Science Foundation(Grant No Y2004A09) of Shandong Province,China
文摘This paper examines the quantization of mesoscopic circuit including Josephson junctions. Following Feynman＇s assumption, via the Hamilton dynamic approach and by virtue of the entangled state representation, it constructs Hamiltonian operator for the double-Josephson-junction mesoscopic circuit coupled by a capacitor. Then it uses the Heisenberg equation of motion to derive the induction voltage across each Josephson junction. The result manifestly shows how the voltage is affected by the capacitance coupling.
文摘The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superconductivity.The surrounding area of the electronic tornado is expanding,which is the basis of the Meissner effect,and the center is contracting,which is the basis of the pinning force.When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force,the electrons form a Cooper pair and release dark energy into virtual space-time.When the dark energy increases to a certain extent,the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave,which fluctuates freely in the superconducting material,which is the basis for the superconducting resistance to be zero.This is similar to the principle of a hot air balloon.The virtual space-time is hot air and the electron pair is a hot air balloon device.Conductor electrons are free and easy to emit dark energy,resulting in insufficient dark energy,and it is not easy to form electron-pair virtual space-time waves,so the superconducting critical temperature is very low.This is because the emission coefficient of the conductor is too high.Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves.Therefore,the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator.The solution of the Qi-space-time wave equation,that is,the coherence coefficient,is an important factor in superconductivity.In addition,the conditions under which tornadoes form are also an important basis for superconductivity.Finally,it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.
文摘The dynamics of the skew information (SI) is investigated for a single Cooper Pair Box (CPB) interacting with a single cavity field. By suitably choosing the system parameters and precisely controlling the dynamics, novel connection is found between the SI and entanglement generation. It is shown that SI can be increased and reach its maximum value either by increasing the number of photons inside the cavity or considering the far off-resonant case.The number of oscillations of SI is increased by decreasing this ratio between the Josephson junction capacity and the gate capacity. This leads to significant improvement of the travelling time between the maximum and minimum values.
文摘We calculate the absorption cross-section for photon by a hydrogen 2s atom using the quantum-classical approximation for the total photo cross-section of many electron atoms. With the application of the first-order term of the Baker Hausdorf expansion, the absorption cross-section for the hydrogen 2s atom decreases to a minimum, the Cooper paJr minimum, at low photon energy. Such a minimum is absent in the exact absorption cross-section for photon by a hydrogen 2s atom. We have extended the calculation for the absorption cross-section of the hydrogen 2s atom using the quantum-classical approximation for the total photo cross-section of many electron to include the second-order term of the Baker-Hausdorf expansion and observed a great reduction in the dip associated with the Cooper pair minimum at the zero crossing.
文摘Individual metallic single-wall carbon nanotubes show unusual non-Ohmic transport behaviors at low and high bias fields. For low-resistance contact samples, the differential conductance increases with increasing bias, reaching a maximum at ~100 mV. As the bias increases further, drops dramatically [1]. The higher the bias, the system behaves in a more normal (Ohmic) manner. This low-bias anomaly is temperature-dependent (50 - 150 K). We propose a new interpretation. Supercurrents run in the graphene wall below ~150 K. The normal hole currents run on the outer surface of the wall, which are subject to the scattering by phonons and impurities. The currents along the tube length generate circulating magnetic fields and eventually destroy the supercurrent in the wall at high enough bias, and restore the Ohmic behavior. If the prevalent ballistic electron model is adopted, then the temperature-dependent scattering effects cannot be discussed. For the high bias (0.3 - 5 V), (a) the I-V curves are temperature-independent (4 - 150 K), and (b) the currents (magnitudes) saturate. The behavior (a) arises from the fact that the neutral supercurrent below the critical temperature is not accelerated by the electric field. The behavior (b) is caused by the limitation of the number of quantum-states for the “holes” running outside of the tube.
文摘The pairon field operator ψ(r,t) evolves, following Heisenberg’s equation of motion. If the Hamiltonian H contains a condensation energy α0(<0) and a repulsive point-like interparticle interaction , , the evolution equation for ψ is non-linear, from which we derive the Ginzburg-Landau (GL) equation: for the GL wave function where σdenotes the state of the condensed Cooper pairs (pairons), and n the pairon density operator (u and are kind of square root density operators). The GL equation with holds for all temperatures (T) below the critical temperature Tc, where εg(T) is the T-dependent pairon energy gap. Its solution yields the condensed pairon density . The T-dependence of the expansion parameters near Tc obtained by GL: constant is confirmed.
