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At least 127 records · Page 7

Ultracoherent superconducting cavity-based multiqudit platform with error-resilient control

Superconducting radio-frequency (SRF) cavities offer a promising platform for quantum computing due to their long coherence times, yet integrating nonlinear elements like transmons for control often introduces additional loss. We report a multimode quantum system based on a 2-cell elliptical-shaped SRF cavity, comprising two cavity modes weakly coupled to an ancillary transmon circuit, designed to preserve coherence while enabling efficient control of the cavity modes. We mitigate the detrimental effects of the transmon decoherence through careful design optimization that reduces transmon-cavity couplings and participation in the dielectric substrate and lossy interfaces, to achieve single-photon lifetimes of 20.6 ms and 15.6 ms for the two modes, and a pure dephasing time exceeding 40 ms. This marks an order-of-magnitude improvement over prior 3D multimode memories. Leveraging sideband interactions and novel error-resilient protocols, including measurement-based correction and post-selection, we achieve high-fidelity control over quantum states. This enables the preparation of Fock states up to N = 20 with fidelities exceeding 95%, the highest reported to date to the authors' knowledge, as well as two-mode entanglement with an estimated coherence-limited fidelities of 99.9% after post-selection. These results establish our platform as a robust foundation for quantum information processing, allowing for future extensions to high-dimensional qudit encodings.

Lu, Yao [Fermilab] (ORCID:000000020413698X)↗

Ultracoherent superconducting cavity-based multiqudit platform with error-resilient control

Superconducting radio-frequency (SRF) cavities offer a promising platform for quantum computing due to their long coherence times, yet integrating nonlinear elements like transmons for control often introduces additional loss. We report a multimode quantum system based on a 2-cell elliptical-shaped SRF cavity, comprising two cavity modes weakly coupled to an ancillary transmon circuit, designed to preserve coherence while enabling efficient control of the cavity modes. We mitigate the detrimental effects of the transmon decoherence through careful design optimization that reduces transmon-cavity couplings and participation in the dielectric substrate and lossy interfaces, to achieve single-photon lifetimes of 20.6 ms and 15.6 ms for the two modes, and a pure dephasing time exceeding 40 ms. This marks an order-of-magnitude improvement over prior 3D multimode memories. Leveraging sideband interactions and novel error-resilient protocols, including measurement-based correction and post-selection, we achieve high-fidelity control over quantum states. This enables the preparation of Fock states up to N = 20 with fidelities exceeding 95%, the highest reported to date to the authors' knowledge, as well as two-mode entanglement with an estimated coherence-limited fidelities of 99.9% after post-selection. These results establish our platform as a robust foundation for quantum information processing, allowing for future extensions to high-dimensional qudit encodings.

Lu, Yao [Fermilab] (ORCID:000000020413698X)↗

Ultracoherent superconducting cavity-based multiqudit platform with error-resilient control

Superconducting radio-frequency (SRF) cavities offer a promising platform for quantum computing due to their long coherence times, yet integrating nonlinear elements like transmons for control often introduces additional loss. We report a multimode quantum system based on a 2-cell elliptical shaped SRF cavity, comprising two cavity modes weakly coupled to an ancillary transmon circuit, designed to preserve coherence while enabling efficient control of the cavity modes. We mitigate the detrimental effects of the transmon decoherence through careful design optimization that reduces transmon-cavity couplings and participation in the dielectric substrate and lossy interfaces, to achieve single-photon lifetimes of 20.6 ms and 15.6 ms for the two modes, and a pure dephasing time exceeding 40 ms. This marks an order-of-magnitude improvement over prior 3D multimode memories. Leveraging sideband interactions and novel error-resilient protocols, including measurement-based correction and post-selection, we achieve high-fidelity control over quantum states. This enables the preparation of Fock states up to $N = 20$ with fidelities exceeding 95%, the highest reported to date to the authors' knowledge, as well as two-mode entanglement with an estimated coherence-limited fidelities of 99.9% after post-selection. These results establish our platform as a robust foundation for quantum information processing, allowing for future extensions to high-dimensional qudit encodings.

Kim, Taeyoon [Fermilab; Northwestern U.]↗

User Interaction with the CNPC Link

As part of NASAs UAS in the NAS project, human factor guidelines are being developed for the ground control station of unmanned aircraft systems. A critical task for the pilot of a UAS is the management and control of the terrestrial radio links used to provide control of the vehicle and relay communications with air traffic control. An analysis of the task of the UAS pilot has been conducted to identify areas where guidelines are required. This analysis has identified a set of information requirements that must be supported by the radio equipment used to provide Control and Non-payload Communication (CNPC). Key requirements include the need for an alert when the link is lost, information on the current quality and latency of the link, and information to enable the future quality of the link to be anticipated as the aircraft changes location. These identified requirements can assist in the development of minimum operational performance standards for CNPC equipment.

unmanned aerial systems↗

Synthesis of Submillimeter Radiation for Spectroscopy

The frequency-multiplier submillimeter spectrometer (FMSS) is a laboratory apparatus for far-infrared molecular spectroscopy, embodying several advances over prior such apparatuses. The most innovative part of the FMSS is a source of monochromatic submillimeter- wavelength radiation that can be tuned over a wide frequency range, as needed for trace gas analyses and molecular- structure studies for which such apparatuses are typically used. The radiation source features a modular design and is built mostly from commercially available components. It includes a computer-controlled radio-frequency synthesizer, amplifiers, and frequency multipliers of a type heretofore used in local oscillators for heterodyne far-infrared receivers. In conjunction with the rest of the apparatus, this source makes it possible to perform measurements over large portions of the submillimeter-wavelength spectrum with resolution, accuracy, and sensitivity greater than those achievable in Fourier-transform infrared spectroscopy. In comparison with prior laboratory submillimeter- wavelength radiation sources, this source is much lighter in weight, less cumbersome, less power-hungry, and capable of sustained operation with less intervention by laboratory personnel. Also, unlike some prior submillimeter-wavelength sources, this source does not require a high-voltage power source. As shown in more detail in the figure, the radiation source includes a sweep frequency synthesizer connected to an external waveform generator, the output of which is used as a reference signal. The synthesizer is computer-controlled through a standard general-purpose interface bus (GPIB) and is operated in phase-locked continuous- wave mode for all measurements. The synthesizer output ranges in frequency from 11 to 18 GHz. For suppression of frequency spurs and harmonics, the output of the frequency synthesizer is fed through a tunable yttrium iron garnet (YIG) filter, which is swept in frequency simultaneously with the frequency synthesizer.

Maiwald, Frank↗

MIDCOURSE GUIDANCE USING RADIO TECHNIQUES

Earth-based radio command of midcourse guidance for lunar flights is described, noting spacecraft, tracking station, and computing facility requirements

RADIO CONTROL↗

Conceptual design and simulator implementation of an automatic terminal approach system

The pilot-machine interface with aircraft automation to increase the safety and utility of single-pilot IFR (instrument flight rules) operations is addressed. An automatic terminal approach system (ATAS), that uses stored instrument approach data to automatically tune aircraft radios and control the aircraft autopilot, was conceived as a means of improving this critical interface. The ATAS automatically flies instrument approach procedures, including the missed approach, and provides for easy pilot interaction to accommodate air traffic control radar vectors and altitude assignments. A research prototype of an ATAS was developed to the extent necessary for a simulation implementation and piloted evaluation. The development of the ATAS concept and the software algorithms is described.

Hinton, D. A.↗

A simulation evaluation of a pilot interface with an automatic terminal approach system

The pilot-machine interface with cockpit automation is a critical factor in achieving the benefits of automation and reducing pilot blunders. To improve this interface, an automatic terminal approach system (ATAS) was conceived that can automatically fly a published instrument approach by using stored instrument approach data to automatically tune airplane radios and control an airplane autopilot and autothrottle. The emphasis in the ATAS concept is a reduction in pilot blunders and work load by improving the pilot-automation interface. A research prototype of an ATAS was developed and installed in the Langley General Aviation Simulator. A piloted simulation study of the ATAS concept showed fewer pilot blunders, but no significant change in work load, when compared with a baseline heading-select autopilot mode. With the baseline autopilot, pilot blunders tended to involve loss of navigational situational awareness or instrument misinterpretation. With the ATAS, pilot blunders tended to involve a lack of awareness of the current ATAS mode state or deficiencies in the pilots' mental model of how the system operated. The ATAS display provided adequate approach status data to maintain situational awareness.

Hinton, David A.↗

Solar wind control of Jupiter's decametric radio emission

Observations of the solar wind close to Jupiter are compared with the decametric radio emission (DAM), using data recorded by Voyager 1 and Voyager 2 during 1979. The Non-Io DAM, recorded by both spacecraft and combined using the superposed epoch technique, is found to correlate with the solar wind density and velocity, as well as with the interplanetary magnetic field (IMF) magnitude. In agreement with earlier work using ground-based observations, there are indications that the Non-Io DAM is somehow associated with magnetic sector structure although the precise details of the relationship are still not known and it is not clear if this is a fundamental effect or some secondary effect of intercorrelation.

Barrow, C. H.↗

Distributed Transforms for Efficient Data Gathering in Sensor Networks

Devices, systems, and techniques for data collecting network such as wireless sensors are disclosed. A described technique includes detecting one or more remote nodes included in the wireless sensor network using a local power level that controls a radio range of the local node. The technique includes transmitting a local outdegree. The local outdegree can be based on a quantity of the one or more remote nodes. The technique includes receiving one or more remote outdegrees from the one or more remote nodes. The technique includes determining a local node type of the local node based on detecting a node type of the one or more remote nodes, using the one or more remote outdegrees, and using the local outdegree. The technique includes adjusting characteristics, including an energy usage characteristic and a data compression characteristic, of the wireless sensor network by selectively modifying the local power level and selectively changing the local node type.

Ortega, Antonio↗

Pulsed radio frequency power modulation for profile control in cryogenic reactive ion etching of silicon gratings

Cryogenic silicon etching with SF 6 /O 2 plasmas enables vertical sidewalls and smooth surfaces for high–aspect-ratio structures, yet precise control of etched profiles (sidewall angle, lateral etching, and linewidth retention) remains challenging under continuous-wave excitation due to coupling among radical fluxes, ion energy distributions, and in situ passivation dynamics. In this work, we investigated pulsed radio frequency bias delivery as a process knob for profile control during cryogenic silicon etching. Systematic experiments on 500 nm-wide, 1 μm-pitch gratings etched to 0.8–1.1 μm depth at 0.5–2 kHz pulsing frequency and 25%–75% duty cycle revealed strong dependencies of etch rate, linewidth, and sidewall angle on modulation conditions. We proposed a conceptual kinetic picture combined with feature-scale electrostatic analysis to understand the alternation of ion-driven etching and passivation recovery between on/off segments and local electric field shaping and modulation of ion trajectories within the trench. Moderate duty cycles (50%–75%) near 1 kHz achieved a balance between anisotropy and etch rate. These results demonstrate pulsed-bias modulation can be utilized to tune directionality and sidewall preservation in cryogenic SF 6 /O 2 etching, which are relevant to photonic, metrology, and quantum device fabrication.

36 MATERIALS SCIENCE↗

AH-1S communication switch integration program

The C-6533/ARC communication system as installed on the test AH-1E Cobra helicopter was modified to allow discrete radio selection of all aircraft radios at the cyclic radio/intercommunication system switch. The current Cobra-fleet use of the C-6533 system is cumbersome, particularly during low-altitude operations. Operationally, the current system C-6533 configuration and design requires the pilot to estimate when he can safely remove his hand from an active flight control to select radios during low-altitude flight. The pilot must then physically remove his hand from the flight control, look inside the cockpit to select and verify the radio selection and then effect the selected radio transmission by activating the radio/ICS switch on the cyclic. This condition is potentially hazardous, especially during low-level flight at night in degraded weather. To improve pilot performance, communications effectiveness, and safety, manprint principles were utilized in the selection of a design modification. The modified C-6533 design was kept as basic as possible for potential Cobra-fleet modification. The communications system was modified and the design was subsequently flight-tested by the U.S. Army Aeroflightdynamics Directorate and NASA at the NASA Ames Research Center, Mountain View, California. The design modification enables the Cobra pilot to maintain hands-on flight controls while selecting radios during nap-of-the-Earth (NOE) flight without looking inside the cockpit which resulted in reduced pilot workload ratings, better pilot handling quality ratings and increased flight safety for the NOE flight environment.

Haworth, Loran↗