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- IEEE Transactions on Ultrasonics, FerroElectrics, and
**Frequency**Control...**oscillator**Data Types:- Other

- IEEE Transactions on Ultrasonics, FerroElectrics, and
**Frequency**Control...**oscillator**Data Types:- Other
- Document

- 6-The electron
**oscillating**period as functions of the temperature and the cyclotron**frequency**in triangular quantum dot**qubit**under an electric field.docx... Fig.4. A-Function relationship between the first excited state energy and the temperature and the electron-phonon coupling constant for different cyclotron**frequencies**and ,,,; B-Function relationship between the first excited energy and the temperature and the electric field strength for different cyclotron**frequencies**and ,,,; C-Function relationship between the first excited energy and the temperature and the confinement length for different cyclotron**frequencies**and ,,,; D-Function relationship between the first excited energy and of the temperature and the Coulomb impurity potential for different cyclotron**frequencies**and ,,,... Fig.1. A-Function relationship between the ground state energy and the temperature and the cyclotron**frequency**for different electron-phonon coupling constants and ,,, ; B-Function relationship between the ground state energy and the temperature and the cyclotron**frequency**for different electric field strengths and ,,,; C-Function relationship between the ground state energy and the temperature and the cyclotron**frequency**for different confinement lengths and ,,,; D-Function relationship between the ground state energy and the temperature and the cyclotron**frequency**for different Coulomb impurity potentials and ,,,... Fig.6. A-The electron**oscillation**period as functions of the temperature and the cyclotron**frequency**for different electron-phonon coupling constants and ,,,; B-The electron**oscillation**period as functions of the temperature and the cyclotron**frequency**for different electric field strengths and,,,; C-The electron**oscillation**period as functions of the temperature and the cyclotron**frequency**for different confinement lengths and ,,,; D-The electron**oscillation**period as functions of the temperature and the cyclotron**frequency**for different Coulomb impurity potentials and ,,,... 7-The electron**oscillating**period as functions of the temperature and the electron-phonon coupling constant and etc. in triangular quantum dot**qubit**under an electric field.docx... 2-The first excited state energy as functions of the temperature and the cyclotron**frequency**in triangular quantum dot**qubit**under an electric field.docx... 3-The ground state energy as functions of the temperature and the electron-phonon coupling constant and etc. in triangular quantum dot**qubit**under an electric field.docx... Fig.7. A-The electron**oscillation**period as functions of the temperature and the electron-phonon coupling constant for different cyclotron**frequencies**and ,,,; B-The electron**oscillation**period as functions of the temperature and the electric field strength for different cyclotron**frequencies**and ,,,; C-The electron**oscillation**period as functions of the temperature and the confinement length for different cyclotron**frequencies**and ,,,; D-The electron**oscillation**period as functions of the temperature and the Coulomb impurity potential for different cyclotron**frequencies**and ,,,... 1-The ground state energy as functions of the temperature and the cyclotron**frequency**in triangular quantum dot**qubit**under an electric field.docx... Fig.3. A-Function relationship between the ground state energy and the temperature and the electron-phonon coupling constant for different cyclotron**frequencies**and ,,,; B-Function relationship between the ground state energy and the temperature and the electric field strength for different cyclotron**frequencies**and ,,,; C-Function relationship between the ground state energy and of the temperature and the confinement length for different cyclotron**frequencies**and ,,,; D-Function relationship between the ground state energy and the temperature and the Coulomb impurity potential for different cyclotron**frequencies**and ,,,Data Types:- Dataset
- Document

- High-fidelity
**qubit**initialization is of significance for efficient error correction in fault tolerant quantum algorithms. Combining two best worlds, speed and robustness, to achieve high-fidelity state preparation and manipulation is challenging in quantum systems, where**qubits**are closely spaced in**frequency**. Motivated by the concept of shortcut to adiabaticity, we theoretically propose the shortcut pulses via inverse engineering and further optimize the pulses with respect to systematic errors in**frequency**detuning and Rabi**frequency**. Such protocol, relevant to**frequency**selectivity, is applied to rare-earth ions**qubit**system, where the excitation of**frequency**-neighboring**qubits**should be prevented as well. Furthermore, comparison with adiabatic complex hyperbolic secant pulses shows that these dedicated initialization pulses can reduce the time that ions spend in the excited state by a factor of 6, which is important in coherence time limited systems to approach an error rate manageable by quantum error correction. The approach may also be applicable to superconducting**qubits**, and any other systems where**qubits**are addressed in**frequency**.Data Types:- Other
- Document

- This dissertation examines the design, fabrication, and characterization of a superconducting lumped-element tunable LC resonator that is used to vary the coupling between two superconducting
**qubits**. Some level of**qubit**-**qubit**coupling is needed to perform gating operations. However, with fixed coupling, single**qubit**operations become considerably more difficult due to dispersive shifts in their energy levels transitions that depend on the state of the other**qubit**. Ideally, one wants a system in which the**qubit**-**qubit**coupling can be turned off to allow for single**qubit**operations, and then turned back on to allow for multi-**qubit**gate operations. I present results on a device that has two fixed-**frequency**transmon**qubits**capacitively coupled to a tunable thin-film LC resonator. The resonator can be tuned in situ over a range of 4.14 GHz to 4.94 GHz by applying an external magnetic flux to two single-Josephson junction loops, which are incorporated into the resonator’s inductance. The**qubits**have 0-to-1 transition**frequencies**of 5.10 GHz and 4.74 GHz. To isolate the system and provide a means for reading out the state of the**qubit**readout, the device was mounted in a 3D Al microwave cavity with a TE101 mode resonance**frequency**of about 6.1 GHz. The flux-dependent transition**frequencies**of the system were measured and fit to results from a coupled Hamiltonian model. With the LC resonator tuned to its minimum resonance**frequency**, I observed a**qubit**-**qubit**dispersive shift of 2χ_qq≈ 0.1 MHz, which was less than the linewidth of the**qubit**transitions. This dispersive shift was sufficiently small to consider the coupling “off”, allowing single**qubit**operations. The**qubit**-**qubit**dispersive shift varied with the applied flux up to a maximum dispersive shift of 2χ_qq≈ 6 MHz. As a proof-of-principle, I present preliminary results on performing a CNOT gate operation on the**qubits**when the coupling was “on” with 2χ_qq≈ 4 MHz. This dissertation also includes observations of the temperature dependence of the relaxation time T1 of three Al/AlOx/Al transmons. We found that, in some cases, T1 increased by almost a factor of two as the temperature increased from 30 mK to 100 mK. We found that this anomalous behavior was consistent with loss due to non-equilibrium quasiparticles in a transmon where one electrode in the tunnel junction had a smaller volume and slightly smaller superconducting energy gap than the other electrode. At sufficiently low temperatures, non-equilibrium quasiparticles accumulate in the electrode with a smaller gap, leading to an increased density of quasiparticles at the junction and a corresponding decrease in the relaxation time. I present a model of this effect, use the model to extract the density of non-equilibrium quasiparticles in the device, and find the values of the two superconducting energy gaps.Data Types:- Other

**frequency**stability... Colpitts**oscillator**Data Types:- Other
- Document

- Data Types:
- Dataset

- Sources of entangled pairs of photons can be used for encoding signals in quantum-encrypted communications, allowing a sender, Alice, and a receiver, Bob, to exchange keys without the possibility of eavesdropping. In fact, any quantum information system would require single and entangled photons to serve as
**qubits**. For this purpose, semiconductor quantum dots (QD) have been extensively studied for their ability to produce entangled light and function as single photon sources. The quality of such sources is evaluated based on three criteria: high efficiency, small multi-photon probability, and quantum indistinguishability. In this work, a simple quantum dot-based LED (E-LED) was used as a quantum light source for on-demand emission, indicating the potential for use as quantum information devices. Limitations of the device include the fine-structure splitting of the quantum dot excitons, their coherence lengths and charge carrier interactions in the structure. The quantum dot-based light emitting diode was initially shown to operate in pulsed mode under AC bias**frequencies**of up to several hundreds of MHz, without compromising the quality of emission. In a Hong-ou-Mandel interference type experiment, the quantum dot photons were shown to interfere with dissimilar photons from a laser, achieving high two-photon interference (TPI) visibilities. Quantum entanglement from a QD photon pair was also measured in pulsed mode, where the QD-based entangled-LED (E-LED) was electrically injected at a**frequency**of 203 MHz. After verifying indistinguishability and good entanglement properties from the QD photons under the above conditions, a quantum relay over 1km of fibre was demonstrated, using input**qubits**from a laser source. The average relay fidelity was high enough to allow for error correction for this BB84-type scheme. To improve the properties of the QD emission, an E-LED was developed based on droplet epitaxy (D-E) QDs, using a different QD growth technique. The relevant chapter outlines the process of QD growth and finally demonstration of quantum entanglement from an electrically injected diode, yielding improvements compared to previous E-LED devices. For the same reason, an alternative method of E-LED operation based on resonant two-photon excitation of the QD was explored. Analysis of Rabi**oscillations**in a quantum dot with a bound exciton state demonstrated coupling of the ground state and the biexciton state by the external**oscillating**field of a laser, therefore allowing the transition between the two states. The results include a considerable improvement in the coherence length of the QD emission, which is crucial for future quantum network applications. We believe that extending this research can find application in quantum cryptography and in realising the interface of a quantum network, based on semiconductor nanotechnology.Data Types:- Other
- Document

**frequency**stability... CMOS, x**frequency**stability, delay time... ring**oscillator**Data Types:- Other
- Document

- circular
**oscillations**Data Types:- Other