arXiv subjects

C. S. Wang

Publications and source records attributed to C. S. Wang.

10 recordsLinked to original sources

arXiv2025

High-impedance resonators for strong coupling to an electron on helium

The in-plane motion of an electron on helium can couple to superconducting microwave resonators via electrical dipole coupling, offering a robust and rapid readout scheme. In previous efforts, microwave resonator designs for electrons on helium have lacked the coupling strength to reach the strong coupling regime, where coherent quantum effects outlast both electron and resonator decoherence rates. High-impedance superconducting microwave resonators offer a path to strong coupling, but integrating such resonators with electrons on helium remains an outstanding challenge. Here, we introduce a high-impedance resonator design compatible with strong coupling to electrons on helium. We fabricate and measure titanium nitride resonators with median internal quality factors of $3.9\times 10^5$ and average impedance of 2.5 k$Ω$, promising a seven-fold increase in coupling strength compared with standard 50$Ω$ resonators. Additionally, we develop a simplified resonator model from the capacitance matrix and sheet inductance that accurately predicts the mode frequencies, significantly simplifying the design process of future resonators for investigating quantum effects with electrons on helium.

quant-ph↗

arXiv2018

Deterministic teleportation of a quantum gate between two logical qubits

A quantum computer has the potential to effciently solve problems that are intractable for classical computers. Constructing a large-scale quantum processor, however, is challenging due to errors and noise inherent in real-world quantum systems. One approach to this challenge is to utilize modularity--a pervasive strategy found throughout nature and engineering--to build complex systems robustly. Such an approach manages complexity and uncertainty by assembling small, specialized components into a larger architecture. These considerations motivate the development of a quantum modular architecture, where separate quantum systems are combined via communication channels into a quantum network. In this architecture, an essential tool for universal quantum computation is the teleportation of an entangling quantum gate, a technique originally proposed in 1999 which, until now, has not been realized deterministically. Here, we experimentally demonstrate a teleported controlled-NOT (CNOT) operation made deterministic by utilizing real-time adaptive control. Additionally, we take a crucial step towards implementing robust, error-correctable modules by enacting the gate between logical qubits, encoding quantum information redundantly in the states of superconducting cavities. Such teleported operations have significant implications for fault-tolerant quantum computation, and when realized within a network can have broad applications in quantum communication, metrology, and simulations. Our results illustrate a compelling approach for implementing multi-qubit operations on logical qubits within an error-protected quantum modular architecture.

quant-ph↗

arXiv2014

Magnetic domain-wall motion twisted by nanoscale probe-induced spin transfer

A method for deterministic control of the magnetic order parameter using an electrical stimulus is highly desired for the new generation of spintronic and magnetoelectronic devices. Much effort has been focused on magnetic domain-wall motion manipulated by a successive injection of spin-polarized current into a magnetic nanostructure. However, an integrant high-threshold current density of 107~108 A/cm2 inhibits the integration of those nanostructures with low-energy-cost technology. In addition, a precise determination of the location of domain walls at nanoscale seems difficult in artificially manufactured nanostructures. Here we report an approach to manipulate a single magnetic domain wall with a perpendicular anisotropy in a manganite/dielectric/metal capacitor using a probe-induced spin displacement. A spin angular momentum transfer torque occurs in the strongly correlated manganite film during the spin injection into the capacitor from the nanoscale magnetized tip with an ultralow voltage of 0.1 V, where the threshold spin-polarized current density is ~104 A/cm2 at the tip/manganite interface. The probe-voltage-controlled domain wall motion in the capacitor demonstrates a critical framework for the fundamental understanding of the manipulation of the nano-magnet systems with low energy consumption.

cond-mat.mtrl-sci↗

arXiv2004

Growth and magnetic properties of MnO2−delta nanowire microspheres

We report the synthesis of MnO2−delta microspheres using hydrothermal and conventional chemical reaction methods. The microspheres of MnO2−delta consist of nanowires having a diameter of 20-50 nm and a length of 2-8 micro m. The value of the oxygen vacancy delta estimated from the x-ray photoelectron spectrum (XPS) is 0.3. The magnetization versus temperature curve indicates a magnetic transition at about 13 K. It is found that a parasitic ferromagnetic component is imposed on the antiferromagnetic structure of MnO2−delta, which might result from distortion of the lattice structure due to oxygen vacancies. The magnetic transition temperature TN is about 10 K lower than that of the bulk MnO2 single crystal.

cond-mat.mtrl-sci↗

arXiv2001

Extraction of nuclear matter properties from nuclear masses by a model of equation of state

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei. It is shown that the volume energy $a_1$ and the nuclear incompressibility $K_0$ depend essentially on $μ_n N+\barμ_p Z-2E_N$, whereas the symmetry energy $J$ and the density symmetry coefficient $L$ as well as symmetry incompressibility $K_s$ depend essentially on $μ_n-\barμ_p$, where $\barμ_p=μ_p-\partial E_C/\partial Z$, $μ_n$ and $μ_p$ are the neutron and proton chemical potentials respectively, $E_N$ the nuclear energy, and $E_C$ the Coulomb energy. The obtained symmetry energy is $J=28.5MeV$, while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.

nucl-th↗

arXiv2001

Effective nucleon mass in relativistic mean field theory

In the $σ$-$ω$-$ρ$ model of the relativistic mean field theory with nonlinear $σ$-meson self-interaction, the effective nucleon mass $M^*$ is discussed with relation to the symmetry incompressibility $K_s$ of nuclear matter, based on the model parameters fitted to nuclear matter properties. It is shown that $M^*$ is larger than $0.73M$, if $K_s$ is assumed to be negative and the nuclear matter incompressibility $K_0$ is kept less than $300 MeV$. Furthermore, the field system is shown to be stable, as the $σ$-meson self-interaction energy is lower bounded in this parameter region.

nucl-th↗

arXiv2001

Nuclear matter properties and relativistic mean-field theory

Nuclear matter properties are calculated in the relativistic mean field theory by using a number of different parameter sets. The result shows that the volume energy $a_1$ and the symmetry energy $J$ are around the acceptable values 16MeV and 30MeV respectively; the incompressibility $K_0$ is unacceptably high in the linear model, but assumes reasonable value if nonlinear terms are included; the density symmetry $L$ is around $100MeV$ for most parameter sets, and the symmetry incompressibility $K_s$ has positive sign which is opposite to expectations based on the nonrelativistic model. In almost all parameter sets there exists a critical point $(ρ_c, δ_c)$, where the minimum and the maximum of the equation of state are coincident and the incompressibility equals zero, falling into ranges 0.014fm$^{-3}<ρ_c<0.039$fm$^{-3}$ and $0.74<δ_c\le0.95$; for a few parameter sets there is no critical point and the pure neutron matter is predicted to be bound. The maximum mass $M_{NS}$ of neutron stars is predicted in the range 2.45M$_\odot\leq M_{NS}\leq 3.26$M$_\odot$, the corresponding neutron star radius $R_{NS}$ is in the range 12.2km$\leq R_{NS}\leq 15.1$km.

nucl-th↗

arXiv2001

Effective nucleon-nucleon interactions and nuclear matter equation of state

Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and Tondeur interactions are written as polynomials of the cubic root of density, with coefficients that are functions of the relative neutron excess $δ$. In the extrapolation toward states far away from the standard one, it is shown that the asymmetry dependence of the critical point ($ρ_c, δ_c$) depends on the model used. However, when the equations of state are fitted to the same standard state, the value of $δ_c$ is almost the same in Skyrme and in Myers-Swiatecki interactions, while is much lower in Tondeur interaction. Furthermore, $δ_c$ does not depend sensitively on the choice of the parameter $γ$ in Skyrme interaction.

nucl-th↗

arXiv2000

Nuclear matter properties in the relativistic mean field model with sigma-omega coupling

The possibility of extending the linear sigma-omega model by introducing a sigma-omega coupling phenomenologically is explored. It is shown that, in contrast to the usual Walecka model, not only the effective nucleon mass M* but also the effective sigma meson mass m*_sigma and the effective omega meson mass m*_omega are nucleon density dependent. When the model parameters are fitted to the nuclear saturation point (the nuclear radius constant r_0=1.14fm and volume energy a_1=16.0MeV) as well as to the effective nucleon mass M*=0.85M, the model yields m*_sigma=1.09m_sigma and m*_omega=0.90m_omega at the saturation point, and the nuclear incompressibility K_0=501MeV. The lowest value of K_0 given by this model by adjusting the model parameters is around 227MeV.

nucl-th↗

arXiv1994

The Crucial Formula for Determination of the Occurrence of the Non-Chaotic States in the rf-biased Nonlinear Oscillators

The crucial formulas to determine the non-chaotic states in the rf-biased nonlinear oscillators are derived from the numerical experiments. The nature of these formulas, which depends on symmetrical properties of the potential well, in terms of the driven-frequency as a function of the damping constant k is investigated. All these ones provide crucial guide posts to check which kinds of solutions (simple or complicated) can be tailored in the dissipative rf-biased nonlinear oscillators, respectively.

chao-dyn↗