| 31. |
- Golubev, Dmitry, et al.
(författare)
-
Single-Photon Detection with a Josephson Junction Coupled to a Resonator
- 2021
-
Ingår i: Physical Review Applied. - 2331-7019. ; 16:1
-
Tidskriftsartikel (refereegranskat)abstract
- We use a semiclassical formalism to optimize a microwave single-photon detector based on switching events of a current-biased Josephson junction coupled to a resonator. To detect very rare events, the average time between dark counts τdark should be maximized taking into account that the switching time τsw should be sufficiently small. We demonstrate that these times can be tuned in a wide range by changing the junction parameters, and τdark/τsw∼109 can be achieved. Therefore, a junction-resonator arrangement can be used to detect extremely low photon fluxes (e.g., for searching for galactic axions).
|
|
| 32. |
- Grebenchuk, S. Yu, et al.
(författare)
-
Nonlocal Long-Range Synchronization of Planar Josephson-Junction Arrays
- 2022
-
Ingår i: Physical Review Applied. - 2331-7019. ; 17:6
-
Tidskriftsartikel (refereegranskat)abstract
- We study arrays of planar Nb Josephson junctions with contacts to intermediate electrodes, which allow measurements of individual junctions and, thus, provide an insight into intricate array dynamics. We observe strong indications for array phase locking, despite a significant interjunction separation. Several unusual phenomena are reported, such as a bistable critical current with reentrant superconductivity upon switching of nearby junctions; and “incorrect” Shapiro steps, occurring at mixing frequencies between the external rf radiation and the internal Josephson frequency in nearby junctions. Our results reveal a surprisingly strong and long-range interjunction interaction, which is attributed to nonlocality of planar-junction electrodynamics, caused by the long-range spreading of stray electromagnetic fields. The nonlocality greatly enhances the high-frequency interjunction coupling and enables large-scale synchronization. Therefore, we conclude that planar geometry is advantageous for the realization of coherent Josephson electronics.
|
|
| 33. |
- Gregefalk, Anton, et al.
(författare)
-
Transitionless quantum driving in spin echo
- 2022
-
Ingår i: Physical Review Applied. - : American Physical Society. - 2331-7019. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- Spin echo can be used to refocus random dynamical phases caused by inhomogeneities in control fields and thereby retain the purity of a spatial distribution of quantum spins. This technique for accurate spin control is an essential ingredient in many applications, such as nuclear magnetic resonance, magnetic resonance imaging, and quantum information processing. Here, we show how all the elements of a spin echo sequence can be performed at high speed by means of transitionless quantum driving. This technique promises accurate control of rapid quantum spin evolution. We apply the scheme to universal nonadiabatic geometric single- and two-qubit gates in a nuclear magnetic resonance setting.
|
|
| 34. |
- Guénot, Diego, et al.
(författare)
-
Distribution of Liquid Mass in Transient Sprays Measured Using Laser-Plasma-Driven X-Ray Tomography
- 2022
-
Ingår i: Physical Review Applied. - 2331-7019. ; 17:6
-
Tidskriftsartikel (refereegranskat)abstract
- We report, the use of laser-plasma-driven x rays to reveal the three-dimensional (3D) structure of a highly atomizing water spray. Soft x rays approximately 5 keV are generated by means of a laser-plasma accelerator. Transmission radiography measurements are performed at different angles, by rotating a multihole injector. Using computer tomography, the local liquid volume distribution and its spatial variation are retrieved in 3D, showing up to 55% liquid fraction at the nozzle outlet, which decreases to below 7% within only 1 mm. The resolution of the liquid volume fraction is 0.5% while the spatial resolution of the radiographic images is 11.5μm. The x-ray source used here provides successful measurements of liquid mass distribution over a relatively large volume and is very promising for the analysis of a variety of challenging transient spray systems, e.g., the injection of liquid synthetic and biofuels used for future clean-combustion applications.
|
|
| 35. |
- Gutierrez Latorre, Martí, 1993, et al.
(författare)
-
Superconducting Microsphere Magnetically Levitated in an Anharmonic Potential with Integrated Magnetic Readout
- 2023
-
Ingår i: Physical Review Applied. - 2331-7019. ; 19:5
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetically levitated superconducting microparticles offer a promising path to quantum experiments with picogram to microgram objects. In this work, we levitate a 700 ng∼1017amu superconducting microsphere in a magnetic chip trap in which detection is integrated. We measure the center-of-mass motion of the particle using a dc superconducting quantum interference device magnetometer. The trap frequencies are continuously tunable between 30 and 160 Hz and the particle remains stably trapped over days in a dilution-refrigerator environment. We characterize the motional-amplitude-dependent frequency shifts, which arise from trap anharmonicities, namely, Duffing nonlinearities and mode couplings. We explain this nonlinear behavior using finite-element modeling of the chip-based trap potential. This work may constitute a first step toward quantum experiments and ultrasensitive inertial sensors with magnetically levitated superconducting microparticles.
|
|
| 36. |
- Havers, Megan, et al.
(författare)
-
Silica seed particles improve the efficiency and throughput of nanoparticle acoustic trapping
- 2024
-
Ingår i: Physical Review Applied. - 2331-7019. ; 21:3
-
Tidskriftsartikel (refereegranskat)abstract
- Silica has rarely been used as a seed particle material in acoustic trapping of nanoparticles. Here we use fluorescent nanoparticles, which are frequently used as a model system, to demonstrate that throughput and nanoparticle trapping efficiency can be improved by using silica seed particles as opposed to traditionally used polystyrene seed particles. The 10 times larger dipole scattering coefficient of silica seed particles compared with polystyrene seed particles in water leads to a higher retention force against fluid flow and thus enables higher throughput. Seed particles retained at an actuation voltage of approximately 10 V p.p. can withstand flow rates up to 2100 ± 200 μl/min for silica and 200 ± 50 μl/min for polystyrene. Furthermore, silica is found to be 40%-2000% more efficient (number of trapped nanoparticles as measured by fluorescent intensity) than polystyrene seed particles in trapping 270-nm polystyrene nanoparticles from suspensions of 1010-1011 particles/ml. Moreover, after enriching nanoparticles into a silica seed particle cluster, the washing flow rate can be increased from 30 μl/min to 200 μl/min (the flow rate at which polystyrene clusters are unstable), halving the total sample processing time without losing the silica seed particle cluster or compromising the nanoparticle trapping efficiency. Thus, material properties (particularly density) of the seed particles are critical to both nanoparticle trapping efficiency and throughput.
|
|
| 37. |
- Hemachandran, E., et al.
(författare)
-
Continuous Droplet Coalescence in a Microchannel Coflow Using Bulk Acoustic Waves
- 2019
-
Ingår i: Physical Review Applied. - 2331-7019. ; 12:4
-
Tidskriftsartikel (refereegranskat)abstract
- The coalescence of liquid droplets with a liquid stream has profound importance in various emerging applications, such as biochemical assays. Acoustic force-based droplet manipulation, which offers unique advantages, is consequently gaining attention. However, the physics of acoustics-driven coalescence of liquid droplets with a liquid stream is not well understood. Here, we unravel the mechanism of coalescence of aqueous droplets flowing in an immiscible (oil) phase with a coflowing aqueous stream, when the system is exposed to acoustic radiation force due to bulk acoustic waves. Our study reveals that the acoustic coalescence phenomenon is governed by the interplay between two important timescales, acoustic migration timescale (τac) and advection timescale (τadv), that underpin the phenomenon. We find that the phenomenon is also governed by the acoustic capillary number (Cac) and relative widths of the coflowing oil and aqueous streams (i.e., Waq and Woil). Our results show that, if Cac<0.9 and Waq>Woil are satisfied to ensure the stability of the streams and positioning of the acoustic node in the aqueous phase, respectively, continuous coalescence is observed for (τadv/τac)≥0.85. We exploit the phenomenon for the extraction of droplet contents (beads and cells) into an aqueous stream.
|
|
| 38. |
- Hillmann, Timo, 1995, et al.
(författare)
-
Designing Kerr Interactions for Quantum Information Processing via Counterrotating Terms of Asymmetric Josephson-Junction Loops
- 2022
-
Ingår i: Physical Review Applied. - 2331-7019. ; 17:6
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous-variable systems realized in high-coherence microwave cavities are a promising platform for quantum information processing. While strong dynamic nonlinear interactions are desired to implement fast and high-fidelity quantum operations, static cavity nonlinearities typically limit the performance of bosonic quantum error-correcting codes. Here we study theoretical models of nonlinear oscillators describing superconducting quantum circuits with asymmetric Josephson-junction loops. Treating the nonlinearity as a perturbation, we derive effective Hamiltonians using the Schrieffer-Wolff transformation. We support our analytical results by numerical experiments and show that the effective Kerr-type couplings can be canceled by an interplay of higher-order nonlinearities. This can be better understood in a simplified model supporting only cubic and quartic nonlinearities. Our results show that a cubic interaction allows an increase in the effective rates of both linear and nonlinear operations without an increase in the undesired anharmonicity of an oscillator which is crucial for many bosonic encodings.
|
|
| 39. |
- Holeňák, Radek, et al.
(författare)
-
Assessing trajectory-dependent electronic energy loss of keV ions by a binary collision approximation code
- 2024
-
Ingår i: Physical Review Applied. - : American Physical Society. - 2331-7019. ; 21:2
-
Tidskriftsartikel (refereegranskat)abstract
- The inelastic energy deposition of energetic ions is a decisive quantity for numerous industrial-scale applications, such as sputtering and ion implantation, yet the underlying physics being governed by dynamic many-particle processes is commonly only qualitatively understood. Recently, transmission experiments on single-crystalline targets (Phys. Rev. Lett. 124, 096601 & Phys. Rev. A 102, 062803) revealed a complex energy scaling of the inelastic energy loss of low-energy ions heavier than protons along different trajectories. We use a Monte Carlo like binary collision approximation code equipped with an impact-parameter-dependent modeling of the inelastic energy losses to assess the role of local contributions to electronic excitations in these cases. We compare angular intensity distributions of calculated trajectories with experimental results for 50-keV 4He and 100-keV 29Si ions transmitted in a time-of-flight setup through single-crystalline silicon (001) foils with nominal thicknesses of 200 and 50 nm, respectively. In these calculations, we employ different models of electronic energy loss, i.e., local and nonlocal forms for light and heavy projectiles. We find that the vast number of projectiles are eventually channeled along their trajectories, regardless of the alignment of the crystal with respect to the incident beam. It is, however, only when local electronic energy loss is considered that the simulated two-dimensional maps and energy distributions show excellent agreement with the experimental results, where channeling leads to significantly reduced stopping, especially for heavier projectiles. We demonstrate the relevance of these effects for ion implantations by assessing the nonlinear and nonmonotonic scaling of the ion range with the thickness of a random surface layer.
|
|
| 40. |
- Holm, Stefan H., et al.
(författare)
-
Microfluidic Particle Sorting in Concentrated Erythrocyte Suspensions
- 2019
-
Ingår i: Physical Review Applied. - 2331-7019. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- An important step in diagnostics is the isolation of specific cells and microorganisms of interest from blood. Since such bioparticles are often present at very low concentrations, throughput needs to be as high as possible. In addition, to ensure simplicity, a minimum of sample preparation is important. Therefore, sorting schemes that function for whole blood are highly desirable. Deterministic lateral displacement (DLD) devices have proven to be very precise and versatile in terms of a wide range of sorting parameters. To better understand how DLD devices perform for blood as the hematocrit increases, we carry out measurements and simulations for spherical particles in the micrometer range which move through DLD arrays for different flow velocities and hematocrits ranging from pure buffer to concentrated erythrocyte suspensions mimicking whole blood. We find that the separation function of the DLD array is sustained even though the blood cells introduce a shift in the trajectories and a significant dispersion for particles whose diameters are close to the critical size in the device. Simulations qualitatively replicate our experimental observations and help us identify fundamental mechanisms for the effect of hematocrit on the performance of the DLD device.
|
|
