### 779 results for qubit oscillator frequency

Contributors: Yan, Ying, Li, Yichao, Kinos, Adam, Walther, Andreas, Shi, Chunyan, Rippe, Lars, Moser, Joel, Kröll, Stefan, Chen, Xi

Date: 2019-03-18

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**. ... 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**.

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Contributors: Ballard, Cody James

Date: 2018-01-01

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. ... 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.

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Contributors: Thit Waso Khine

Date: 2019-10-24

**frequency** stability...**Oscillator** circuit is one that converts DC power into AC power at a **frequency** without any input signal. **Oscillators** are commonly used in communication systems to generate carrier **frequency** ranging from audio **frequency** 20 Hz to radio **frequency** 100G Hz . There are two main classes of **oscillators**, harmonic **oscillator** with sinusoidal output e.g. sine wave and relaxation **oscillator** with non sinusoidal output e.g. square wave, triangle wave, etc. . In this paper, class A Colpitts **oscillator** with LC feedback circuit is designed as a radio **frequency** **oscillator** to generate the output signals at 5M Hz. After designing, this circuit is simulated with Multisim software to analyze the effect of power supply on its **frequency** stability. Three supply voltages, 14 V, 12 V and 10 V are set as sample parameters to analyze the variation of **frequency** and voltage of the output signal. Changing DC power supply one by one as the above selected parameters in Multisim, the change of value of **frequencies** are noted and output signal results are also shown with the help of virtual **oscillator**. Thit Waso Khine "Designing Class a Colpitts **Oscillator** and Analyzing the Effect of DC Power Supply on its **Frequency** Stability" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28022.pdf...Colpitts **oscillator** ... **Oscillator** circuit is one that converts DC power into AC power at a **frequency** without any input signal. **Oscillators** are commonly used in communication systems to generate carrier **frequency** ranging from audio **frequency** 20 Hz to radio **frequency** 100G Hz . There are two main classes of **oscillators**, harmonic **oscillator** with sinusoidal output e.g. sine wave and relaxation **oscillator** with non sinusoidal output e.g. square wave, triangle wave, etc. . In this paper, class A Colpitts **oscillator** with LC feedback circuit is designed as a radio **frequency** **oscillator** to generate the output signals at 5M Hz. After designing, this circuit is simulated with Multisim software to analyze the effect of power supply on its **frequency** stability. Three supply voltages, 14 V, 12 V and 10 V are set as sample parameters to analyze the variation of **frequency** and voltage of the output signal. Changing DC power supply one by one as the above selected parameters in Multisim, the change of value of **frequencies** are noted and output signal results are also shown with the help of virtual **oscillator**. Thit Waso Khine "Designing Class a Colpitts **Oscillator** and Analyzing the Effect of DC Power Supply on its **Frequency** Stability" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28022.pdf

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Top results from Data Repository sources. Show only results like these.

Contributors: Zou, Xudong, Seshia, Ashwin

Date: 2015-04-28

**Oscillators**...Linear models for **oscillator** noise predict an improvement in **frequency** stability with increasing Quality factor. Although it is well known that this result does not apply to non-linear **oscillators**, systematic experimental investigations of the impact of damping on **frequency** stability of non-linear MEMS **oscillators** has not been previously reported. This paper studies the **frequency** stability of a nonlinear MEMS **oscillator** under variable damping conditions. Analytical and experimental investigation of a MEMS square-wave **oscillator** embedding a double-ended tuning fork resonator driven into the non-linear regime is introduced. The experimental results indicate that for a pre-set drive level, the variation of air-damping changes the onset of nonlinear behaviour in the resonator, which not only impacts the output **frequency** but also the phase/**frequency** noise of a nonlinear MEMS square wave **oscillator**. The random walk **frequency** noise and flicker **frequency** noise levels are strongly correlated with the non-linear operating point of the resonator, whereas the white phase and white **frequency** noise levels are impacted both by the output power and by operative nonlinearities. ... Linear models for **oscillator** noise predict an improvement in **frequency** stability with increasing Quality factor. Although it is well known that this result does not apply to non-linear **oscillators**, systematic experimental investigations of the impact of damping on **frequency** stability of non-linear MEMS **oscillators** has not been previously reported. This paper studies the **frequency** stability of a nonlinear MEMS **oscillator** under variable damping conditions. Analytical and experimental investigation of a MEMS square-wave **oscillator** embedding a double-ended tuning fork resonator driven into the non-linear regime is introduced. The experimental results indicate that for a pre-set drive level, the variation of air-damping changes the onset of nonlinear behaviour in the resonator, which not only impacts the output **frequency** but also the phase/**frequency** noise of a nonlinear MEMS square wave **oscillator**. The random walk **frequency** noise and flicker **frequency** noise levels are strongly correlated with the non-linear operating point of the resonator, whereas the white phase and white **frequency** noise levels are impacted both by the output power and by operative nonlinearities.

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Contributors: Owen, Edmund Thomas, Barnes, Crispin H. W.

Date: 2013-09-04

Quantum states can contain correlations which are stronger than is possible in classical systems. Quantum information technologies use these correlations, which are known as entanglement, as a resource for implementing novel protocols in a diverse range of fields such as cryptography, teleportation and computing. However, current methods for generating the required entangled states are not necessarily robust against perturbations in the proposed systems. In this thesis, techniques will be developed for robustly generating the entangled states needed for these exciting new technologies.
The thesis starts by presenting some basic concepts in quantum information proccessing. In Ch. 2, the numerical methods which will be used to generate solutions for the dynamic systems in this thesis are presented. It is argued that using a GPU-accelerated staggered leapfrog technique provides a very efficient method for propagating the wave function.
In Ch. 3, a new method for generating maximally entangled two-**qubit** states using a pair of interacting particles in a one-dimensional harmonic **oscillator** is proposed. The robustness of this technique is demonstrated both analytically and numerically for a variety of interaction potentials. When the two **qubits** are initially in the same state, no entanglement is generated as there is no direct **qubit**-**qubit**
interaction. Therefore, for an arbitrary initial state, this process implements a root-of-swap entangling quantum gate. Some possible physical implementations of this proposal for low-dimensional semiconductor
systems are suggested.
One of the most commonly used **qubits** is the spin of an electron. However, in semiconductors, the spin-orbit interaction can couple this **qubit** to the electron's momentum. In order to incorporate this e ffect
into our numerical simulations, a new discretisation of this interaction is presented in Ch. 4 which is signi ficantly more accurate than traditional methods. This technique is shown to be similar to the standard discretisation for magnetic fields.
In Ch. 5, a simple spin-precession model is presented to predict the eff ect of the spin-orbit interaction on the entangling scheme of Ch. 3. It is shown that the root-of-swap quantum gate can be restored by introducing an additional constraint on the system. The robustness of the gate to perturbations in this constraint is demonstrated by presenting numerical solutions using the methods of Ch. 4. ... Quantum states can contain correlations which are stronger than is possible in classical systems. Quantum information technologies use these correlations, which are known as entanglement, as a resource for implementing novel protocols in a diverse range of fields such as cryptography, teleportation and computing. However, current methods for generating the required entangled states are not necessarily robust against perturbations in the proposed systems. In this thesis, techniques will be developed for robustly generating the entangled states needed for these exciting new technologies.
The thesis starts by presenting some basic concepts in quantum information proccessing. In Ch. 2, the numerical methods which will be used to generate solutions for the dynamic systems in this thesis are presented. It is argued that using a GPU-accelerated staggered leapfrog technique provides a very efficient method for propagating the wave function.
In Ch. 3, a new method for generating maximally entangled two-**qubit** states using a pair of interacting particles in a one-dimensional harmonic **oscillator** is proposed. The robustness of this technique is demonstrated both analytically and numerically for a variety of interaction potentials. When the two **qubits** are initially in the same state, no entanglement is generated as there is no direct **qubit**-**qubit**
interaction. Therefore, for an arbitrary initial state, this process implements a root-of-swap entangling quantum gate. Some possible physical implementations of this proposal for low-dimensional semiconductor
systems are suggested.
One of the most commonly used **qubits** is the spin of an electron. However, in semiconductors, the spin-orbit interaction can couple this **qubit** to the electron's momentum. In order to incorporate this e ffect
into our numerical simulations, a new discretisation of this interaction is presented in Ch. 4 which is signi ficantly more accurate than traditional methods. This technique is shown to be similar to the standard discretisation for magnetic fields.
In Ch. 5, a simple spin-precession model is presented to predict the eff ect of the spin-orbit interaction on the entangling scheme of Ch. 3. It is shown that the root-of-swap quantum gate can be restored by introducing an additional constraint on the system. The robustness of the gate to perturbations in this constraint is demonstrated by presenting numerical solutions using the methods of Ch. 4.

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Contributors: Omar Farouk Djibril , Gerard L. Gbaguidi Aisse, Gbaguidi S. Victor and Antoine Cokou Vianou.

Date: 2019-04-05

Portico **Frequency** of free **oscillations** Resonance Stiffness matrix method....In the modern world, high-rise buildings are in vogue, each year more and more large buildings built. One of the most common schemes for high-rise buildings is portico system, formed by combination of vertical (columns) and horizontal (beams) supporting members. However, as building grows in height, it must have enough strength and stiffness to withstand lateral loads imposed by wind or moderate earthquakes. Over last ten decades, there was therefore significant renewed interest in structures stability problem subjected to time-dependent loads. Considering dynamic problems in civil engineering field is necessary to ensure structure reliability in many applications. But dynamics problems study is often complex for inertia forces come from structure displacements which in turn depend on structures free **oscillations** **frequency**. The coincidence of this **frequency** of free **oscillation** with that of the forced **oscillations** caused by the wind involves the phenomenon of resonance which is very dangerous for the structures. It is therefore necessary to know how to determine the **frequency** of the free **oscillations** of the systems which constitutes the starting point for a dynamic study. To do this, the stiffness matrix method was used to determine the free **oscillation** **frequencies** of the multi-storey portico structures. It has been observed, therefore, that the **frequencies** of free **oscillations** don?t depend on time, neither on the amplitude of the **oscillations**, nor on the phase angle, but rather on the rigidity and the mass of the structures. ... In the modern world, high-rise buildings are in vogue, each year more and more large buildings built. One of the most common schemes for high-rise buildings is portico system, formed by combination of vertical (columns) and horizontal (beams) supporting members. However, as building grows in height, it must have enough strength and stiffness to withstand lateral loads imposed by wind or moderate earthquakes. Over last ten decades, there was therefore significant renewed interest in structures stability problem subjected to time-dependent loads. Considering dynamic problems in civil engineering field is necessary to ensure structure reliability in many applications. But dynamics problems study is often complex for inertia forces come from structure displacements which in turn depend on structures free **oscillations** **frequency**. The coincidence of this **frequency** of free **oscillation** with that of the forced **oscillations** caused by the wind involves the phenomenon of resonance which is very dangerous for the structures. It is therefore necessary to know how to determine the **frequency** of the free **oscillations** of the systems which constitutes the starting point for a dynamic study. To do this, the stiffness matrix method was used to determine the free **oscillation** **frequencies** of the multi-storey portico structures. It has been observed, therefore, that the **frequencies** of free **oscillations** don?t depend on time, neither on the amplitude of the **oscillations**, nor on the phase angle, but rather on the rigidity and the mass of the structures.

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Contributors: Lüders, Klaus, Pohl, Robert Otto, Beuermann, Gustav, Samwer, Konrad

Date: 2003-01-01

circular **oscillations**...Through superposition of the linear **oscillations** of two leaf springs of almost equal **frequencies**, linear, elliptic and circular **oscillations** can be generated and shown by optical projection. ... Through superposition of the linear **oscillations** of two leaf springs of almost equal **frequencies**, linear, elliptic and circular **oscillations** can be generated and shown by optical projection.

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Contributors: Sadegh Biabanifard, S. Mehdi Hosseini Largani, Shahrouz Asadi

Date: 2015-06-26

**frequency** stability...CMOS, x **frequency** stability, delay time...ring **oscillator**...A combined skewed ring **oscillator** by different type of delay stages is presented. This paper aims to drive a high stable and relatively high **frequency** but still use a full transistor circuit for ring **oscillator** with combined delay stages and skewed connections. First we propose two types of common inverters then calculate their delay time and analysis their dependence of delay time to variation of power supply voltage. The simulation results verify that delay time of these two CMOS inverters show opposite behaviour versus power supply changing. So a combined structure can obtain more appropriate **frequency** stability versus power supply noise. Also in order to increase **oscillation** **frequency** we have used the negative skewed delay connections. The simulation results using HSPICE for 0.18 µm CMOS shows a good agreement with analysis results. In addition in this paper the mathematical justification for improved functioning of this combined skewed ring **oscillator** has been proved. This justification shows appropriate agreement with the simulation results. From mathematical point of view the proposed ring **oscillator** has better **frequency** stability in comparison with other types of ring **oscillators**. In fact, the **oscillation** **frequency** sensitivity to supply voltage noise is reduced considerably. ... A combined skewed ring **oscillator** by different type of delay stages is presented. This paper aims to drive a high stable and relatively high **frequency** but still use a full transistor circuit for ring **oscillator** with combined delay stages and skewed connections. First we propose two types of common inverters then calculate their delay time and analysis their dependence of delay time to variation of power supply voltage. The simulation results verify that delay time of these two CMOS inverters show opposite behaviour versus power supply changing. So a combined structure can obtain more appropriate **frequency** stability versus power supply noise. Also in order to increase **oscillation** **frequency** we have used the negative skewed delay connections. The simulation results using HSPICE for 0.18 µm CMOS shows a good agreement with analysis results. In addition in this paper the mathematical justification for improved functioning of this combined skewed ring **oscillator** has been proved. This justification shows appropriate agreement with the simulation results. From mathematical point of view the proposed ring **oscillator** has better **frequency** stability in comparison with other types of ring **oscillators**. In fact, the **oscillation** **frequency** sensitivity to supply voltage noise is reduced considerably.

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Contributors: Qasem M. Al-Mdallal

Date: 2012-04-25

Lock-on; streamwise **oscillation**; transverse
**oscillation**; fluid forces...This paper presents results obtained from the
numerical solution for the flow past an **oscillating** circular cylinder at
Reynolds number of 200. The **frequency** of **oscillation** was fixed to
the vortex shedding **frequency** from a fixed cylinder, f0, while the
amplitudes of **oscillations** were varied from to 1.1a, where a
represents the radius of the cylinder. The response of the flow
through the fluid forces acting on the surface of the cylinder are
investigated. The lock-on phenomenon is captured at low **oscillation**
amplitudes. ... This paper presents results obtained from the
numerical solution for the flow past an **oscillating** circular cylinder at
Reynolds number of 200. The **frequency** of **oscillation** was fixed to
the vortex shedding **frequency** from a fixed cylinder, f0, while the
amplitudes of **oscillations** were varied from to 1.1a, where a
represents the radius of the cylinder. The response of the flow
through the fluid forces acting on the surface of the cylinder are
investigated. The lock-on phenomenon is captured at low **oscillation**
amplitudes.

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Contributors: Puissant, Stéphane, Lee, Young June

Date: 2016-12-31

FIGURE 8. Hyalessa fuscata. Echemes structure. A, Power **frequency** spectrum represented with overlay of 47 spectra computed from echemes with high amplitude **oscillations** showing dominant **frequencies** marked by F1, F2, F3 and F4. B, Detailed oscillogram showing the first echeme with low amplitude **oscillations** and the second echeme with high amplitude **oscillations**. C, Power **frequency** spectrum represented with overlay of 38 spectra computed from echemes with low amplitude **oscillations** showing dominant **frequencies** marked by F1 and F2. ... FIGURE 8. Hyalessa fuscata. Echemes structure. A, Power **frequency** spectrum represented with overlay of 47 spectra computed from echemes with high amplitude **oscillations** showing dominant **frequencies** marked by F1, F2, F3 and F4. B, Detailed oscillogram showing the first echeme with low amplitude **oscillations** and the second echeme with high amplitude **oscillations**. C, Power **frequency** spectrum represented with overlay of 38 spectra computed from echemes with low amplitude **oscillations** showing dominant **frequencies** marked by F1 and F2.

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