Research of the design of a coupler with an operating frequency of 1.8 GHz has been conducted. This construction has a small area and can be used in microwave circuits for power division. Suggested ...construction, taking into consideration the reduced dimensions, has characteristics comparable to the design in the traditional version. Miniaturization of the device was achieved by using synthesized microstrip cells which were installed instead of ordinary sections. The coupler was modeled and fabricated and the measured characteristics are well coincide with the calculations.
With the development of multistandard, multiband wireless/microwave circuits and systems, a wide stopband could be essential for a substrate integrated waveguide (SIW) filter to eliminate ...interference. However, the performance of the current wide-stopband SIW filters is not good enough, particularly the stopband extension. Here, based on a multilayer SIW filter without degrading its passband performance, we advance the slot element into a slot array as the intercoupling structure to significantly improve the stopband extension upper limit. It is achieved by splitting the conventional magnetic intercoupling slot element into a slot array with Formula Omitted parts and moving them away from the edge by about 0.5/(Formula Omitted + 1) of the edge’s length. For an SIW filter working in TE101 (Formula Omitted), one can use Type-0, Formula Omitted, and Type-Formula Omitted slot arrays to eliminate all the spurious modes below Formula Omitted and extend the stopband to (Formula Omitted + 3)Formula Omitted. In this paper, we present three prototypes that respectively use 2–4 types of slot arrays. Without complex design or passband degradation, the measured results show that their stopbands are, respectively, extended up to Formula Omitted, Formula Omitted, and Formula Omitted, which are significantly better than those of their counterparts based on the slot element. The proposed technology should be efficient for developing high-performance wide-stopband SIW filters in wireless/microwave circuits and systems.
In this paper, a new type of microwave microfluidic sensor is proposed to detect and determine the dielectric properties of common liquids. The technique is based on perturbation theory, in which the ...resonant frequency and quality factor of the microwave resonator depend on the dielectric properties of the resonator. A microstrip split-ring resonator with two gaps is adopted for the design of the sensors (i.e., a double split-ring resonator). This resonator is both compact and planar, making it suitable for a lab-on-a-chip approach. Several types of solvents are tested with two types of capillaries to verify sensor performance. At 3 GHz, very good agreement is demonstrated between simulated and measured results.
We provide an explicit construction of a universal gate set for continuous-variable quantum computation with microwave circuits. Such a universal set has been first proposed in quantum-optical ...setups, but its experimental implementation has remained elusive in that domain due to the difficulties in engineering strong nonlinearities. Here, we show that a realistic three-wave mixing microwave architecture based on the superconducting nonlinear asymmetric inductive element Frattini et al., Appl. Phys. Lett. 110, 222603 (2017) allows us to overcome this difficulty. As an application, we show that this architecture allows for the generation of a cubic phase state with an experimentally feasible procedure. This work highlights a practical advantage of microwave circuits with respect to optical systems for the purpose of engineering non-Gaussian states and opens the quest for continuous-variable algorithms based on few repetitions of elementary gates from the continuous-variable universal set.
The theory of electric polarization in crystals defines the dipole moment of an insulator in terms of a Berry phase (geometric phase) associated with its electronic ground state. This concept not ...only solves the long-standing puzzle of how to calculate dipole moments in crystals, but also explains topological band structures in insulators and superconductors, including the quantum anomalous Hall insulator and the quantum spin Hall insulator, as well as quantized adiabatic pumping processes. A recent theoretical study has extended the Berry phase framework to also account for higher electric multipole moments, revealing the existence of higher-order topological phases that have not previously been observed. Here we demonstrate experimentally a member of this predicted class of materials-a quantized quadrupole topological insulator-produced using a gigahertz-frequency reconfigurable microwave circuit. We confirm the non-trivial topological phase using spectroscopic measurements and by identifying corner states that result from the bulk topology. In addition, we test the critical prediction that these corner states are protected by the topology of the bulk, and are not due to surface artefacts, by deforming the edges of the crystal lattice from the topological to the trivial regime. Our results provide conclusive evidence of a unique form of robustness against disorder and deformation, which is characteristic of higher-order topological insulators.
Magnetism typically arises from the joint effect of Fermi statistics and repulsive Coulomb interactions, which favours ground states with non-zero electron spin. As a result, controlling spin ...magnetism with electric fields-a longstanding technological goal in spintronics and multiferroics
-can be achieved only indirectly. Here we experimentally demonstrate direct electric-field control of magnetic states in an orbital Chern insulator
, a magnetic system in which non-trivial band topology favours long-range order of orbital angular momentum but the spins are thought to remain disordered
. We use van der Waals heterostructures consisting of a graphene monolayer rotationally faulted with respect to a Bernal-stacked bilayer to realize narrow and topologically non-trivial valley-projected moiré minibands
. At fillings of one and three electrons per moiré unit cell within these bands, we observe quantized anomalous Hall effects
with transverse resistance approximately equal to h/2e
(where h is Planck's constant and e is the charge on the electron), which is indicative of spontaneous polarization of the system into a single-valley-projected band with a Chern number equal to two. At a filling of three electrons per moiré unit cell, we find that the sign of the quantum anomalous Hall effect can be reversed via field-effect control of the chemical potential; moreover, this transition is hysteretic, which we use to demonstrate non-volatile electric-field-induced reversal of the magnetic state. A theoretical analysis
indicates that the effect arises from the topological edge states, which drive a change in sign of the magnetization and thus a reversal in the favoured magnetic state. Voltage control of magnetic states can be used to electrically pattern non-volatile magnetic-domain structures hosting chiral edge states, with applications ranging from reconfigurable microwave circuit elements to ultralow-power magnetic memories.
The modern understanding of the Josephson effect in mesosopic devices derives from the physics of Andreev bound states, fermionic modes that are localized in a superconducting weak link. Recently, ...Josephson junctions constructed using semiconducting nanowires have led to the realization of superconducting qubits with gate-tunable Josephson energies. We have used a microwave circuit QED architecture to detect Andreev bound states in such a gate-tunable junction based on an aluminum-proximitized indium arsenide nanowire. We demonstrate coherent manipulation of these bound states, and track the bound-state fermion parity in real time. Individual parity-switching events due to nonequilibrium quasiparticles are observed with a characteristic timescale T_{parity}=160±10 μs. The T_{parity} of a topological nanowire junction sets a lower bound on the bandwidth required for control of Majorana bound states.
This article introduces the deep neural network method into the field of high-dimensional microwave modeling. Deep learning is nowadays highly successful in solving complex and challenging pattern ...recognition and classification problems. This article investigates the use of deep neural networks to solve microwave modeling problems that are much more challenging than that solved by the previous shallow neural networks. The most commonly used activation function in the existing deep neural network is the rectified linear unit (ReLU), which is a piecewise hard switch function. However, such a ReLU is not suitable for microwave modeling where the input-output relationships are smooth and continuous. In this article, we propose a new deep neural network to perform high-dimensional microwave modeling. A smooth ReLU is proposed for the new deep neural network. The proposed deep neural network employs both the sigmoid function and the smooth ReLU as activation functions. The new deep neural network can represent the smooth input-output relationship that is required for microwave modeling. An advanced three-stage deep learning algorithm is proposed to train the new deep neural network model. This algorithm can determine the number of hidden layers with sigmoid functions and those with smooth ReLUs in the training process. It can also overcome the vanishing gradient problem for training the deep neural network. The proposed deep neural network technique can solve microwave modeling problems in a higher dimension than the previous neural network method, i.e., shallow neural network method. Two high-dimensional parameter-extraction modeling examples of microwave filters are presented to demonstrate the proposed deep neural network technique.
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