1,242 research outputs found
Measuring and controlling radio-frequency quanta with superconducting circuits
No full textIn this thesis, we will present the theoretical and experimental work that led to the realization of Radio-Frequency Circuit QuantumElectro-Dynamics (RFcQED). In chapter 1, I will introduce the field of circuit quantum electrodynamics (QED), and the motivations for extending this field to radio frequencies. In chapter 2, we provide a detailed derivation of the Hamiltonian of circuit QED formulated in the context of the Rabi model, and extract expressions for the cross-Kerr interaction. The resulting requirements for the coupling rate in RFcQED are discussed, one of them being the need to dramatically increase the coupling rate compared to typical circuit QED device. In chapter 3 we cover two experimental approaches to increasing the coupling in a circuit QED system, one making use of a high impedance resonator, the second utilizing a large coupling capacitor. In chapter 4, we combine these two approaches to implement RFcQED. Through strong dispersive coupling, we could measure individual photons in a megahertz resonator, demonstrate quantum control by cooling the resonator to the ground state or preparing Fock states, and finally observe with nanosecond resolution the rethermalization of these states. In chapter 5 we present QuCAT or Quantum Circuit Analyzer Tool in Python, a software package that can be used for the design of circuit QED systems such as the one presented here in this thesis. In chapter 6 we discuss how certain interplays between general relativity and quantum mechanics cannot be described using our current laws of physics. In particular, we show how radio-frequency mechanical oscillators are perfect candidates to performexperiments in this regime. In chapter 7 we present the prospects for coupling such mechanical oscillator to weakly anharmonic superconducting circuits such as the transmon qubits or RFcQED systems. In chapter 8, we provide an outlook.Casimir PhD Series, Delft-Leiden 2020-09QN/Steele La
A massive squeeze
No full textA Cooper-pair box qubit is used to squeeze the energy of a heavy oscillating membrane towards a quantum energy eigenstate, bringing measurements of how mass and quantum mechanics interplay one step closer
TIPE KEPRIBADIAN TOKOH UTAMA PADA NOVEL “INTROVER” KARYA M.F. HAZIM
No full textThe author tries to analyze the personality of the main characters using the study of literary psychology, whether the main character is more melancholic or pblegmatic. M.F. Hazim in his novel "Introver" tells the story of the world intover. Reading it, we are invited to explore in the mind and soul of an introver who is always nervous, restless, and upset; also the inner conflict that torments him, and how he finds "friends" to fill his loneliness and make his life more meaningful. The author wants to know more clearly what exactly the lives of introverts are in their daily lives. This research is directed to one main problem, namely "What is the personality type of the main character introver in the" Introver "novel by M.F. Hazim ". This research uses descriptive qualitative method with heuristic and hermeneutic reading techniques in order to understand and reveal "something" contained in literary works. The results of the research that have been carried out are in accordance with the research hypothesis, namely the main character Nawawi has an introvert personality type in the novel "Introver" by M.F. Hajim. Researchers found 42 quotes stating that Nawawi has an introverted personality type. Of the 42 quotes that have been found, 28 quotes state that Nawawi has a melancholic personality type and 14 quotes state that Nawawi has a phlegmatic personality type
QuCAT: Quantum circuit analyzer tool in Python
No full textQuantum circuits constructed from Josephson junctions and superconducting electronics are key to many quantum computing and quantum optics applications. Designing these circuits involves calculating the Hamiltonian describing their quantum behavior. Here we present QuCAT, or 'Quantum Circuit Analyzer Tool', an open-source framework to help in this task. This open-source Python library features an intuitive graphical or programmatical interface to create circuits, the ability to compute their Hamiltonian, and a set of complimentary functionalities such as calculating dissipation rates or visualizing current flow in the circuit.QN/Steele La
Phonon-number resolution of voltage-biased mechanical oscillators with weakly anharmonic superconducting circuits
No full textObserving quantum phenomena in macroscopic objects, and the potential discovery of a fundamental limit in the applicability of quantum mechanics, has been a central topic of modern experimental physics. Highly coherent and heavy micromechanical oscillators controlled by superconducting circuits are a promising system for this task. Here we focus in particular on the electrostatic coupling of motion to a weakly anharmonic circuit, namely, the transmon qubit. In the case of a megahertz mechanical oscillator coupled to a gigahertz transmon, we explain the difficulties in bridging the large electromechanical frequency gap. To remedy this issue, we explore the requirements to reach phonon-number resolution in the resonant coupling of a megahertz transmon and a mechanical oscillator.QN/Steele La
Nature of the Lamb shift in weakly anharmonic atoms: From normal-mode splitting to quantum fluctuations
No full textWhen a two-level system (TLS) is coupled to an electromagnetic resonator, its transition frequency changes in response to the quantum vacuum fluctuations of the electromagnetic field, a phenomenon known as the Lamb shift. Remarkably, by replacing the TLS by a harmonic oscillator, normal-mode splitting leads to a quantitatively similar shift, without taking quantum fluctuations into account. In a weakly anharmonic system, lying in between the harmonic oscillator and a TLS, the origins of such shifts can be unclear. An example of this is the dispersive shift of a transmon qubit in circuit quantum electrodynamics (QED). Although often referred to as a Lamb shift, the dispersive shift observed in spectroscopy in circuit QED could contain a significant contribution from normal-mode splitting that is not driven by quantum fluctuations, raising the question: how much of this shift is quantum in origin? Here we treat normal-mode splitting separately from shifts induced by quantum vacuum fluctuations in the Hamiltonian of a weakly anharmonic system, providing a framework for understanding the extent to which observed frequency shifts can be attributed to quantum fluctuations.QN/Steele La
Erratum: QuCAT: Quantum circuit analyzer tool in python (New Journal of Physics (2020) 22 (013025) DOI: 10.1088/1367-2630/ab60f6)
No full textIn the published paper, the Hamiltonian featured in figure 2 was incorrect. The term EJ/(12h) should be EJ/(24h), as shown in the corrected figure in this corrigendum. Note that this error was simply typographic, and was never reflected in the QuCAT software. (Figure Presented).Corrigendum DOI ...QN/Steele La
Beyond Lesson Studies and Design Experiments: Using theoretical tools in practice and finding out how they work
No full textThis paper aims to illustrate how fruitful insights into the link between school teaching practice and student learning outcomes can be theoretically grounded by the variation theory from the field of phenomenography; and from this framework demonstrate how a 'pedagogy of awareness' can be implemented in the classroom. In this study, five teachers and 162 students at Primary Four level of school education in Hong Kong participated and the practice of the 'learning study' was adopted. By comparing the results of pre- and posttests, a significant gain was observed in the students learning outcomes.
Measuring industry-science links through inventor-author relations: A profiling method
No full textIn this pilot study we examine the performance of text-based profiling in recovering a set of validated inventor-author links. In a first step we match patents and publications solely based on their similarity in content. Next, we compare inventor and author names on the highest ranked matches for the occurrence of name matches. Finally, we compare these candidate matches with the names listed in a validated set of inventor-author names. Our text-based profile methodology performs significantly better than a random matching of patents and publications, suggesting that text-based profiling is a valuable complementary tool to the name searches used in previous studies.innovation; industry-science links; text-based profiling;
Helical mode interactions and spectral energy transfer in magnetohydrodynamic turbulence
No full textSpectral transfer processes in magnetohydrodynamic (MHD) turbulence are investigated by decomposition of the velocity and magnetic fields in Fourier space into helical modes. In 1992, Waleffe (Phys. Fluids A, 4:350 (1992)) used this decomposition to calculate triad interactions for isotropic hydrodynamic turbulence and determined whether a given triad contributed to forward or reverse energy transfer depending on the helicities of the interacting modes. The problem becomes more difficult in MHD due to the need to treat a coupled system of partial differential equations and the energy transfers between the magnetic and velocity fields. This requires the development of techniques that extend Waleffe's work, which are subsequently used to calculate the direction of energy transfer processes originating from triad interactions derived from the MHD equations. In order to illustrate the possible transfer processes that arise from helical mode interactions, we focus on simplified cases and putting special emphasis on interactions resulting in reverse spectral energy transfer. This approach also proves to be helpful in determining the nature of certain energy transfer processes, where transfer of energy between different fields and between the same field can be distinguished. Reverse transfer of magnetic energy was found if the helicities of two modes corresponding to the smaller wavenumbers are the same, while for reverse transfer of kinetic energy Waleffe's result is recovered. Reverse transfer of kinetic to magnetic energy is facilitated if the interacting magnetic field modes are of opposite helicity, and no reverse transfer of magnetic to kinetic energy was found. More generally, the direction of energy transfer not only depends on helicity but also on the ratio of magnetic to kinetic energy. For the magnetically dominated case reverse transfer occurs of all helicities are the same, the kinetically dominated case two modes need to have the same helicity while the third mode is of opposite helicity to allow reverse transfer
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