scholarly journals Modal Birefringence: Tunable Modal Birefringence in a Low‐Loss Van Der Waals Waveguide (Adv. Mater. 27/2019)

2019 ◽  
Vol 31 (27) ◽  
pp. 1970198
Author(s):  
Debo Hu ◽  
Ke Chen ◽  
Xinzhong Chen ◽  
Xiangdong Guo ◽  
Mengkun Liu ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Low Loss ◽  
Modal Birefringence

Tunable Modal Birefringence in a Low‐Loss Van Der Waals Waveguide

2019 ◽  
Vol 31 (27) ◽  
pp. 1807788 ◽  
Author(s):  
Debo Hu ◽  
Ke Chen ◽  
Xinzhong Chen ◽  
Xiangdong Guo ◽  
Mengkun Liu ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Low Loss ◽  
Modal Birefringence

scholarly journals Miniaturizing transmon qubits using van der Waals materials

2021 ◽  
Author(s):  
Abhinandan Antony ◽  
Martin Gustafsson ◽  
Guilhem Ribeill ◽  
Matthew Ware ◽  
Anjaly Rajendran ◽  
...  
Keyword(s):  
Parallel Plate ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Spatial Density ◽  
Quantum Computers ◽  
Low Loss ◽  
Quantum Devices ◽  
Lossy Dielectrics ◽  
Circuit Components ◽  
High Coherence

Abstract Quantum computers can potentially achieve an exponential speedup versus classical computers on certain computational tasks, recently demonstrated in systems of superconducting qubits. However, the capacitor electrodes that comprise these qubits must be large in order to avoid lossy dielectrics. This tactic hinders scaling by increasing parasitic coupling among circuit components, degrading individual qubit addressability, and limiting the spatial density of qubits. Here, we take advantage of the unique properties of van der Waals (vdW) materials to reduce the qubit area by $>1000$ times while preserving the required capacitance without increasing substantial loss. Our qubits combine conventional aluminum-based Josephson junctions with parallel-plate capacitors composed of crystalline layers of superconducting niobium diselenide and insulating hexagonal-boron nitride. We measure a vdW transmon $T_1$ relaxation time of 1.06 $\mu$s, which demonstrates a path to achieve high-qubit-density quantum processors with long coherence times, and the broad utility of layered heterostructures in low-loss, high-coherence quantum devices.

scholarly journals Edge-oriented and steerable hyperbolic polaritons in anisotropic van der Waals nanocavities

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhigao Dai ◽  
Guangwei Hu ◽  
Guangyuan Si ◽  
Qingdong Ou ◽  
Qing Zhang ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Degrees Of Freedom ◽  
Optical Axis ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Real Space ◽  
Crystallographic Direction ◽  
Tuning Parameter ◽  
Low Loss ◽  
Plane Anisotropy

AbstractHighly confined and low-loss polaritons are known to propagate isotropically over graphene and hexagonal boron nitride in the plane, leaving limited degrees of freedom in manipulating light at the nanoscale. The emerging family of biaxial van der Waals materials, such as α-MoO3 and V2O5, support exotic polariton propagation, as their auxiliary optical axis is in the plane. Here, exploiting this strong in-plane anisotropy, we report edge-tailored hyperbolic polaritons in patterned α-MoO3 nanocavities via real-space nanoimaging. We find that the angle between the edge orientation and the crystallographic direction significantly affects the optical response, and can serve as a key tuning parameter in tailoring the polaritonic patterns. By shaping α-MoO3 nanocavities with different geometries, we observe edge-oriented and steerable hyperbolic polaritons as well as forbidden zones where the polaritons detour. The lifetime and figure of merit of the hyperbolic polaritons can be regulated by the edge aspect ratio of nanocavity.

scholarly journals In-plane anisotropic and ultra-low-loss polaritons in a natural van der Waals crystal

Nature ◽  
2018 ◽  
Vol 562 (7728) ◽  
pp. 557-562 ◽  
Author(s):  
Weiliang Ma ◽  
Pablo Alonso-González ◽  
Shaojuan Li ◽  
Alexey Y. Nikitin ◽  
Jian Yuan ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Low Loss

scholarly journals Making high-quality quantum microwave devices with van der Waals superconductors

2021 ◽  
Author(s):  
Abhinandan Antony ◽  
Martin V. Gustafsson ◽  
Anjaly Rajendran ◽  
Avishai Benyamini ◽  
Guilhem Ribeill ◽  
...  
Keyword(s):  
Quantum Coherence ◽  
Van Der Waals ◽  
Layered Materials ◽  
Low Loss ◽  
High Quality ◽  
Quantum Devices ◽  
2D Layered Materials ◽  
Value Sets ◽  
Microwave Regime ◽  
Quality Factor Q

Abstract Ultra low-loss microwave materials are crucial for enhancing quantum coherence and scalability of superconducting qubits. Van der Waals (vdW) heterostructure is an attractive platform for quantum devices due to the single-crystal structure of the constituent two-dimensional (2D) layered materials and the lack of dangling bonds at their atomically sharp interfaces. However, new fabrication and characterization techniques are required to determine whether these structures can achieve low loss in the microwave regime. Here we report the fabrication of superconducting microwave resonators using NbSe$_2$ that achieve a quality factor $Q > 10^5$. This value sets an upper bound that corresponds to a resistance of $\leq 192 \mu\Omega$ when considering the additional loss introduced by integrating NbSe$_2$ into a standard transmon circuit. This work demonstrates the compatibility of 2D layered materials with high-quality microwave quantum devices.

High-efficiency modulation of coupling between different polaritons in an in-plane graphene/hexagonal boron nitride heterostructure

Nanoscale ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 2703-2709 ◽  
Author(s):  
Xiangdong Guo ◽  
Hai Hu ◽  
Debo Hu ◽  
Baoxin Liao ◽  
Ke Chen ◽  
...  
Keyword(s):  
Boron Nitride ◽  
High Efficiency ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Two Dimensional ◽  
Low Loss ◽  
Nanophotonic Devices ◽  
Phonon Polaritons ◽  
Graphene Plasmons

Two-dimensional van der Waals (vdW) materials have a full set of highly confined polariton modes, such as low-loss phonon polaritons and dynamically tunable graphene plasmons, which provide a solution for integrated nanophotonic devices by combining the unique advantages of different polaritons.

Broad spectral tuning of ultra-low-loss polaritons in a van der Waals crystal by intercalation

2020 ◽  
Vol 19 (9) ◽  
pp. 964-968 ◽  
Author(s):  
Javier Taboada-Gutiérrez ◽  
Gonzalo Álvarez-Pérez ◽  
Jiahua Duan ◽  
Weiliang Ma ◽  
Kyle Crowley ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Spectral Tuning ◽  
Low Loss

Low-Loss Images in a Stem/Tem Microscope

1976 ◽  
Vol 34 ◽  
pp. 496-497 ◽  
Author(s):  
David C. Joy ◽  
Dennis M. Maher
Keyword(s):  
High Resolution ◽  
Surface Topography ◽  
Beam Direction ◽  
Low Loss ◽  
Specimen Holder ◽  
Glancing Angle ◽  
High Resolution Images ◽  
Set Up ◽  
Conventional Manner ◽  
Objective Type

High-resolution images of the surface topography of solid specimens can be obtained using the low-loss technique of Wells. If the specimen is placed inside a lens of the condenser/objective type, then it has been shown that the lens itself can be used to collect and filter the low-loss electrons. Since the probeforming lenses in TEM instruments fitted with scanning attachments are of this type, low-loss imaging should be possible.High-resolution, low-loss images have been obtained in a JEOL JEM 100B fitted with a scanning attachment and a thermal, fieldemission gun. No modifications were made to the instrument, but a wedge-shaped, specimen holder was made to fit the side-entry, goniometer stage. Thus the specimen is oriented initially at a glancing angle of about 30° to the beam direction. The instrument is set up in the conventional manner for STEM operation with all the lenses, including the projector, excited.

Edge Penetration Effects in the Low-Loss Electron Image in the SEM

1988 ◽  
Vol 46 ◽  
pp. 202-203
Author(s):  
Oliver C. Wells
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Beam Energy ◽  
Secondary Electron ◽  
Sharp Edge ◽  
Beam Diameter ◽  
Low Loss ◽  
Additional Information ◽  
Electron Image ◽  
Scanning Electron

The low-loss electron (LLE) image in the scanning electron microscope (SEM) is useful for the study of uncoated photoresist and some other poorly conducting specimens because it is less sensitive to specimen charging than is the secondary electron (SE) image. A second advantage can arise from a significant reduction in the width of the “penetration fringe” close to a sharp edge. Although both of these problems can also be solved by operating with a beam energy of about 1 keV, the LLE image has the advantage that it permits the use of a higher beam energy and therefore (for a given SEM) a smaller beam diameter. It is an additional attraction of the LLE image that it can be obtained simultaneously with the SE image, and this gives additional information in many cases. This paper shows the reduction in penetration effects given by the use of the LLE image.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

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