scholarly journals Granular superconductors for high kinetic inductance and low loss quantum devices

2020 ◽  
Vol 117 (6) ◽  
pp. 062601 ◽  
Author(s):  
Aviv Glezer Moshe ◽  
Eli Farber ◽  
Guy Deutscher
Keyword(s):  
Kinetic Inductance ◽  
Low Loss ◽  
Quantum Devices ◽  
Granular Superconductors

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 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.

scholarly journals Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Alexander Anferov ◽  
Aziza Suleymanzade ◽  
Andrew Oriani ◽  
Jonathan Simon ◽  
David I. Schuster
Keyword(s):  
Millimeter Wave ◽  
Four Wave Mixing ◽  
Kinetic Inductance ◽  
Wave Mixing ◽  
Quantum Devices

scholarly journals Quantum sensors for microscopic tunneling systems

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander Bilmes ◽  
Serhii Volosheniuk ◽  
Jan David Brehm ◽  
Alexey V. Ustinov ◽  
Jürgen Lisenfeld
Keyword(s):  
Electric Fields ◽  
Applied Strain ◽  
Control Individual ◽  
Quantum Computers ◽  
Superconducting Qubit ◽  
Low Loss ◽  
Quantum Devices ◽  
Two Level Systems ◽  
And Control ◽  
Hybrid Quantum System

AbstractThe anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become particularly important for micro-fabricated quantum devices such as superconducting qubits, where they are a major source of decoherence. Here, we present a method to characterize individual TLS in virtually arbitrary materials deposited as thin films. The material is used as the dielectric in a capacitor that shunts the Josephson junction of a superconducting qubit. In such a hybrid quantum system the qubit serves as an interface to detect and control individual TLS. We demonstrate spectroscopic measurements of TLS resonances, evaluate their coupling to applied strain and DC-electric fields, and find evidence of strong interaction between coherent TLS in the sample material. Our approach opens avenues for quantum material spectroscopy to investigate the structure of tunneling defects and to develop low-loss dielectrics that are urgently required for the advancement of superconducting quantum computers.

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.

STEM Study of Surface Plasmon Excitation in Small Spherical Particles

1990 ◽  
Vol 48 (2) ◽  
pp. 42-43
Author(s):  
Daniel UGARTE
Keyword(s):  
Energy Loss ◽  
Spherical Particles ◽  
Small Particles ◽  
Bulk Materials ◽  
Low Loss ◽  
Plasmon Excitation ◽  
Surface Modes ◽  
Surface Plasmon Excitation ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Small particles exhibit chemical and physical behaviors substantially different from bulk materials. This is due to the fact that boundary conditions can induce specific constraints on the observed properties. As an example, energy loss experiments carried out in an analytical electron microscope, constitute a powerful technique to investigate the excitation of collective surface modes (plasmons), which are modified in a limited size medium. In this work a STEM VG HB501 has been used to study the low energy loss spectrum (1-40 eV) of silicon spherical particles [1], and the spatial localization of the different modes has been analyzed through digitally acquired energy filtered images. This material and its oxides have been extensively studied and are very well characterized, because of their applications in microelectronics. These particles are thus ideal objects to test the validity of theories developed up to now.Typical EELS spectra in the low loss region are shown in fig. 2 and energy filtered images for the main spectral features in fig. 3.

Investigation of cluster layers of small netal particles by TEM, SEM, EELS and by photoacoustic spectroscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 250-251
Author(s):  
H. Seiler ◽  
U. Haas ◽  
K.H. Körtje
Keyword(s):  
Bulk Material ◽  
High Vacuum ◽  
Optical Methods ◽  
Metal Particles ◽  
Silver Particles ◽  
Low Loss ◽  
Plasmon Excitation ◽  
First Results ◽  
Diffraction Patterns ◽  
Small Metal Particles

The physical properties of small metal particles reveal an intermediate position between atomic and bulk material. Especially Ag has shown pronounced size effects. We compared silver layers evaporated in high vacuum with cluster layers of small silver particles, evaporated in N2 at a pressure of about 102 Pa. The investigations were performed by electron optical methods (TEM, SEM, EELS) and by Photoacoustic (PA) Spectroscopy (gas-microphone detection).The observation of cluster layers with TEM and high resolution SEM show small silver particles with diameters of about 50 nm (Fig. 1 and Figure 2, respectively). The electron diffraction patterns of homogeneous Ag layers and of cluster layers are similar, whereas the low loss EELS spectra due to plasmon excitation are quite different. Fig. 3 and Figure 4 show first results of EELS spectra of a cluster layer of small silver particles on carbon foil and of a homogeneous Ag layer, respectively.

Quantitative energy-filtered tem imaging of interfaces

1996 ◽  
Vol 54 ◽  
pp. 542-543 ◽  
Author(s):  
J. Bentley ◽  
E. A. Kenik ◽  
K. Siangchaew ◽  
M. Libera
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Unit Volume ◽  
Core Loss ◽  
Mean Free Path ◽  
Slit Width ◽  
Elemental Mapping ◽  
Low Loss ◽  
Transmission Electron ◽  
Inelastic Mean Free Path

Quantitative elemental mapping by inner shell core-loss energy-filtered transmission electron microscopy (TEM) with a Gatan Imaging Filter (GIF) interfaced to a Philips CM30 TEM operated with a LaB6 filament at 300 kV has been applied to interfaces in a range of materials. Typically, 15s exposures, slit width Δ = 30 eV, TEM magnifications ∼2000 to 5000×, and probe currents ≥200 nA, were used. Net core-loss maps were produced by AE−r background extrapolation from two pre-edge windows. Zero-loss I0 (Δ ≈ 5 eV) and “total” intensity IT (unfiltered, no slit) images were used to produce maps of t/λ = ln(IT/I0), where λ is the total inelastic mean free path. Core-loss images were corrected for diffraction contrast by normalization with low-loss images recorded with the same slit width, and for changes in thickness by normalization with t/λ, maps. Such corrected images have intensities proportional to the concentration in atoms per unit volume. Jump-ratio images (post-edge divided by pre-edge) were also produced. Spectrum lines across planar interfaces were recorded with TEM illumination by operating the GIF in the spectroscopy mode with an area-selecting slit oriented normal to the energy-dispersion direction. Planar interfaces were oriented normal to the area-selecting slit with a specimen rotation holder.

Sign in / Sign up

Export Citation Format

Share Document