| 1. |
- Fadavi Roudsari, Anita, 1978, et al.
(författare)
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Three-wave mixing traveling-wave parametric amplifier with periodic variation of the circuit parameters
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 122:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the implementation of a near-quantum-limited, traveling-wave parametric amplifier that uses three-wave mixing (3WM). To favor amplification by 3WM, we use superconducting nonlinear asymmetric inductive element (SNAIL) loops, biased with a dc magnetic flux. In addition, we equip the device with dispersion engineering features to create a stopband at the second harmonic of the pump and suppress the propagation of the higher harmonics that otherwise degrade the amplification. With a chain of 440 SNAILs, the amplifier provides up to 20 dB gain and a 3-dB bandwidth of 1 GHz. The added noise by the amplifier is found to be less than one photon.
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| 2. |
- Li, Hangxi, 1994, et al.
(författare)
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Experimentally Verified, Fast Analytic, and Numerical Design of Superconducting Resonators in Flip-Chip Architectures
- 2023
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Ingår i: IEEE Transactions on Quantum Engineering. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- In superconducting quantum processors, the predictability of device parameters is of increasing importance as many laboratories scale up their systems to larger sizes in a 3-D-integrated architecture. In particular, the properties of superconducting resonators must be controlled well to ensure high-fidelity multiplexed readout of qubits. Here, we present a method, based on conformal mapping techniques, to predict a resonator's parameters directly from its 2-D cross-section, without computationally heavy and time-consuming 3-D simulation. We demonstrate the method's validity by comparing the calculated resonator frequency and coupling quality factor with those obtained through 3-D finite-element-method simulation and by measurement of 15 resonators in a flip-chip-integrated architecture. We achieve a discrepancy of less than 2% between designed and measured frequencies for 6-GHz resonators. We also propose a design method that reduces the sensitivity of the resonant frequency to variations in the interchip spacing.
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| 3. |
- Renberg Nilsson, Hampus, 1993, et al.
(författare)
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High-Gain Traveling-Wave Parametric Amplifier Based on Three-Wave Mixing
- 2023
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Ingår i: Physical Review Applied. - 2331-7019. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- We extend the theory for a Josephson-junction traveling-wave parametric amplifier (TWPA) operat-ing in the three-wave-mixing regime and we propose a scheme for achieving high gain. The continuous three-mode model [P.K. Tien, J. Appl. Phys. 29, 1347 (1958)] is, on one hand, extended to describe a discrete chain of Josephson junctions at high frequencies close to the spectral cutoff where there is no up -conversion. On the other hand, we also develop a continuous multimode theory for the small frequency limit where the frequency dispersion is close to linear. We find that in both cases the gain is significantly reduced compared to the prediction by the continuous three-mode model as the result of increasingly strong dispersion at the high frequencies and generation of up-converted modes at the small frequencies. The developed theory is in quantitative agreement with simulations of the full solution of the dynamical equations. To recover the high gain, we propose to engineer a chain with dispersive features to form a two-band frequency spectrum and to place the pump frequency within the upper band close to the spectral cutoff. We prove that there exists a sweet spot, where the signal and the pump are phase matched, while the up-conversion is inhibited. This results in a high gain, which grows exponentially with the length of the TWPA.
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| 4. |
- Verma, Amit, et al.
(författare)
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Low-Temperature Effects on Electron Transport in Small-Diameter Silicon Nanowire
- 2023
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Ingår i: 2023 IEEE Nanotechnology Materials and Devices Conference (NMDC). - 9798350335460 ; , s. 31-34
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Konferensbidrag (refereegranskat)abstract
- We report on modeling studies on the effect of very low temperatures (4K-77K) on the behavior of electron transport in a [110] axially aligned, 1.3 nm diameter unstrained silicon nanowire (SiNW). A sp3d5s * tight-binding scheme is used to calculate the band structure within an Ensemble Monte Carlo simulation. Electron scattering occurs through bulk-acoustic and bulk-optical phonons and includes intra-subband and inter-subband events. A comparison with room temperature (300K) shows that at lower temperatures, average electron steady-state drift velocity increases by 2 or more times at relatively moderate electric fields. Transient average electron velocity also shows a more pronounced streaming motion. This is attributed to an overall decrease in electron-phonon scattering rates with temperature.
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