27 research outputs found
Intermodulation Distortion in a Josephson Traveling Wave Parametric Amplifier
Josephson traveling wave parametric amplifiers enable the amplification of
weak microwave signals close to the quantum limit with large bandwidth, which
has a broad range of applications in superconducting quantum computing and in
the operation of single-photon detectors. While the large bandwidth allows for
their use in frequency-multiplexed detection architectures, an increased number
of readout tones per amplifier puts more stringent requirements on the dynamic
range to avoid saturation. Here, we characterize the undesired mixing processes
between the different frequency-multiplexed tones applied to a Josephson
traveling wave parametric amplifier, a phenomenon also known as intermodulation
distortion. The effect becomes particularly significant when the amplifier is
operated close to its saturation power. Furthermore, we demonstrate that
intermodulation distortion can lead to significant crosstalk and reduction of
fidelity for multiplexed readout of superconducting qubits. We suggest using
large detunings between the pump and signal frequencies to mitigate crosstalk.
Our work provides insights into the limitations of current Josephson traveling
wave parametric amplifiers and highlights the importance of performing further
research on these devices.Comment: 11 pages, 12 figure
Calibration of Drive Non-Linearity for Arbitrary-Angle Single-Qubit Gates Using Error Amplification
The ability to execute high-fidelity operations is crucial to scaling up
quantum devices to large numbers of qubits. However, signal distortions
originating from non-linear components in the control lines can limit the
performance of single-qubit gates. In this work, we use a measurement based on
error amplification to characterize and correct the small single-qubit rotation
errors originating from the non-linear scaling of the qubit drive rate with the
amplitude of the programmed pulse. With our hardware, and for a 15-ns pulse,
the rotation angles deviate by up to several degrees from a linear model. Using
purity benchmarking, we find that control errors reach , which
accounts for half of the total gate error. Using cross-entropy benchmarking, we
demonstrate arbitrary-angle single-qubit gates with coherence-limited errors of
and leakage below . While the exact
magnitude of these errors is specific to our setup, the presented method is
applicable to any source of non-linearity. Our work shows that the
non-linearity of qubit drive line components imposes a limit on the fidelity of
single-qubit gates, independent of improvements in coherence times, circuit
design, or leakage mitigation when not corrected for
Fast Flux-Activated Leakage Reduction for Superconducting Quantum Circuits
Quantum computers will require quantum error correction to reach the low
error rates necessary for solving problems that surpass the capabilities of
conventional computers. One of the dominant errors limiting the performance of
quantum error correction codes across multiple technology platforms is leakage
out of the computational subspace arising from the multi-level structure of
qubit implementations. Here, we present a resource-efficient universal leakage
reduction unit for superconducting qubits using parametric flux modulation.
This operation removes leakage down to our measurement accuracy of in approximately with a low error of on the computational subspace, thereby reaching durations and
fidelities comparable to those of single-qubit gates. We demonstrate that using
the leakage reduction unit in repeated weight-two stabilizer measurements
reduces the total number of detected errors in a scalable fashion to close to
what can be achieved using leakage-rejection methods which do not scale. Our
approach does neither require additional control electronics nor on-chip
components and is applicable to both auxiliary and data qubits. These benefits
make our method particularly attractive for mitigating leakage in large-scale
quantum error correction circuits, a crucial requirement for the practical
implementation of fault-tolerant quantum computation
The Role of Mobile Health Technologies in Allergy Care:an EAACI Position Paper
Mobile health (mHealth) uses mobile communication devices such as smartphones and tablet computers to support and improve health-related services, data and information flow, patient self-management, surveillance, and disease management from the moment of first diagnosis to an optimized treatment. The European Academy of Allergy and Clinical Immunology created a task force to assess the state of the art and future potential of mHealth in allergology. The task force endorsed the "Be He@lthy, Be Mobile" WHO initiative and debated the quality, usability, efficiency, advantages, limitations, and risks of mobile solutions for allergic diseases. The results are summarized in this position paper, analyzing also the regulatory background with regard to the "General Data Protection Regulation" and Medical Directives of the European Community. The task force assessed the design, user engagement, content, potential of inducing behavioral change, credibility/accountability, and privacy policies of mHealth products. The perspectives of healthcare professionals and allergic patients are discussed, underlining the need of thorough investigation for an effective design of mHealth technologies as auxiliary tools to improve quality of care. Within the context of precision medicine, these could facilitate the change in perspective from clinician- to patient-centered care. The current and future potential of mHealth is then examined for specific areas of allergology, including allergic rhinitis, aerobiology, allergen immunotherapy, asthma, dermatological diseases, food allergies, anaphylaxis, insect venom, and drug allergy. The impact of mobile technologies and associated big data sets are outlined. Facts and recommendations for future mHealth initiatives within EAACI are listed
Research needs in allergy: an EAACI position paper, in collaboration with EFA
Abstract In less than half a century, allergy, originally perceived as a rare disease, has become a major public health threat, today affecting the lives of more than 60 million people in Europe, and probably close to one billion worldwide, thereby heavily impacting the budgets of public health systems. More disturbingly, its prevalence and impact are on the rise, a development that has been associated with environmental and lifestyle changes accompanying the continuous process of urbanization and globalization. Therefore, there is an urgent need to prioritize and concert research efforts in the field of allergy, in order to achieve sustainable results on prevention, diagnosis and treatment of this most prevalent chronic disease of the 21 st century. The European Academy of Allergy and Clinical Immunology (EAACI) is the leading professional organization in the field of allergy, promoting excellence in clinical care, education, training and basic and translational research, all with the ultimate goal of improving the health of allergic patients. The European Federation of Allergy and Airways Diseases Patients' Associations (EFA) is a non-profit network of allergy, asthma and Chronic Obstructive Pulmonary Disorder (COPD) patients' organizations. In support of their missions, the present EAACI Position Paper, in collaboration with EFA, highlights the most important research needs in the field of allergy to serve as key recommendations for future research funding at the national and European levels. Although allergies may involve almost every organ of the body and an array of diverse external factors act as triggers, there are several common themes that need to be prioritized in research efforts. As in many other chronic diseases, effective prevention, curative treatment and accurate, rapid diagnosis represent major unmet needs. Detailed phenotyping/endotyping stands out as widely required in order to arrange or re-categorize clinical syndromes into more coherent, uniform and treatment-responsive groups. Research efforts to unveil the basic pathophysiologic pathways and mechanisms, thus leading to the comprehension and resolution of the pathophysiologic complexity of allergies will allow for the design of novel patient-oriented diagnostic and treatment protocols. Several allergic diseases require well-controlled epidemiological description and surveillance, using disease registries, pharmacoeconomic evaluation, as well as large biobanks. Additionally, there is a need for extensive studies to bring promising new biotechnological innovations, such as biological agents, vaccines of modified allergen molecules and engineered components for allergy diagnosis, closer to clinical practice. Finally, particular attention should be paid to the difficult-to-manage, precarious and costly severe disease forms and/or exacerbations. Nonetheless, currently arising treatments, mainly in the fields of immunotherapy and biologicals, hold great promise for targeted and causal management of allergic conditions. Active involvement of all stakeholders, including Patient Organizations and policy makers are necessary to achieve the aims emphasized herein