Experimental Quantum Randomness Processing

Coherently manipulating multipartite quantum correlations leads to remarkable advantages in quantum information processing. A fundamental question is whether such quantum advantages persist only by exploiting multipartite correlations, such as entanglement. Recently, Dale, Jennings, and Rudolph negated the question by showing that a randomness processing, quantum Bernoulli factory, using quantum coherence, is strictly more powerful than the one with classical mechanics. In this Letter, focusing on the same scenario, we propose a theoretical protocol that is classically impossible but can be implemented solely using quantum coherence without entanglement. We demonstrate the protocol by exploiting the high-fidelity quantum state preparation and measurement with a superconducting qubit in the circuit quantum electrodynamics architecture and a nearly quantum-limited parametric amplifier. Our experiment shows the advantage of using quantum coherence of a single qubit for information processing even when multipartite correlation is not present.Comment: 9 pages, 7 figure

The experimental realization of high-fidelity `shortcut-to-adiabaticity' quantum gates in a superconducting Xmon qubit

Based on a `shortcut-to-adiabaticity' (STA) scheme, we theoretically design and experimentally realize a set of high-fidelity single-qubit quantum gates in a superconducting Xmon qubit system. Through a precise microwave control, the qubit is driven to follow a fast `adiabatic' trajectory with the assistance of a counter-diabatic field and the correction of derivative removal by adiabatic gates. The experimental measurements of quantum process tomography and interleaved randomized benchmarking show that the process fidelities of our STA quantum gates are higher than 94.9% and the gate fidelities are higher than 99.8%, very close to the state-of-art gate fidelity of 99.9%. An alternate of high-fidelity quantum gates is successfully achieved under the STA protocol.Comment: 18 pages, 6 figure

CHARACTERIZATION OF METAL-OXIDE-SEMICONDUCTOR STRUCTURES AT LOW TEMPERATURES USING SELF-ALIGNED AND VERTICALLY COUPLED ALUMINUM AND SILICON SINGLE-ELECTRON TRANSISTORS

I incorporate an Al-AlOx-Al single-electron transistor (SET) as the gate of a narrow (~ 100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET). Near the MOSFET channel conductance threshold, Coulomb blockade oscillations are observed at about 20 millikelvin, revealing the formation of a Si SET at the Si/SiO2 interface. Based on a simple electrostatic model, the two SET islands are demonstrated to be closely aligned, with an inter-island capacitance approximately equal to 1/3 of the total capacitance of the Si transistor island, indicating that the Si transistor is strongly coupled to the Al transistor. This vertically-aligned Al and Si SET system is used to characterize the background charges in a MOS structure at low temperature, which may also be sources of decoherence for Si quantum computation. A single charge defect, probably either a single charge trap at the Si/SiO2 interface or a single donor in the Si substrate, is detected and the properties of the defect are studied in this dissertation

Significantly Increased Public Interest in Sleep Disorder during the COVID-19 Pandemic: An Analysis of Google Trends Data

Background: The COVID-19 pandemic has had a profound impact on sleep disorders. Previous studies have shown that people's sleep time is delayed. Methods: Analyze the public's interest to the keyword "sleep disorder" during the COVID-19 pandemic from December 2019 to December 2022 using Google Trends. The study also focused on the search trend data of the top three countries with high to low overall search frequency for this keyword. Results: It has been observed that during the peak period of the COVID-19 pandemic, the public's search interest for "sleep disorder" has significantly increased. Analyzing Google Trends from December 2019 to December 2022, the top three countries with high interest in searching for "sleep disorder" are the United States, the Philippines, and Canada. It shows that search interest in the United States is an increasing trend year by year, and the overall trend is relatively stable. The search trend for "sleep disorder" among Filipino netizens fluctuates greatly and is generally on a downward trend. The search trend for "sleep disorder" among Canadian netizens is moderate, and the overall trend is like that of Filipinos. It is worth noting that the Google Trends for "sleep disorder" among Filipino and Canadian netizens has changed from an overall increase to an overall decrease in 2020 as the watershed. This indicates a temporal correlation between the surge in COVID-19 cases and online search for "sleep disorder". Conclusion: It shows that public interest in "sleep disorder" has significantly increased during the COVID-19 pandemic, and there may be a certain correlation between the COVID-19 pandemic and sleep disorders. These are worthy of further exploration by researchers, especially the changes in people's daily routines caused by the COVID-19 pandemic, which in turn affect people's sleep quality

Temperature-dependent transport in a sixfold degenerate two-dimensional electron system on a H-Si(111) surface

Low-field magnetotransport measurements on a high mobility (mu=110,000 cm^2/Vs) two-dimensional (2D) electron system on a H-terminated Si(111) surface reveal a sixfold valley degeneracy with a valley splitting <= 0.1 K. The zero-field resistivity rho_{xx} displays strong temperature dependence for 0.07 < T < 25 K as predicted for a system with high degeneracy and large mass. We present a method for using the low-field Hall coefficient to probe intervalley momentum transfer (valley drag). The relaxation rate is consistent with Fermi liquid theory, but a small residual drag as T->0 remains unexplained.Comment: 5 pages, 4 figures; revised and slightly shortened for publication