Dissertations / Theses on the topic 'Quantum feedback control'
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Edwards, Simon C. "Optimal feedback control of quantum states." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435452.
Full textCombes, Joshua Leo Alfred. "Rapid measurement and purification using quantum feedback control." Thesis, Griffith University, 2010. http://hdl.handle.net/10072/366812.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
Full Text
Barter, Oliver. "Deterministic quantum feedback control in probabilistic atom-photon entanglement." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:9faa5f68-39fa-4bd2-9362-785b3cd0111e.
Full textMiao, Zibo. "Feedback control of quantum systems : modelling, stabilisation and estimation." Phd thesis, Canberra, ACT : The Australian National University, 2015. http://hdl.handle.net/1885/155798.
Full textLolli, Jared. "Quantum Measurement and Feedback Control of highly nonclassical Photonic States." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC223/document.
Full textIn recent years, the field of quantum optics has thrived thanks to the possibility of controlling light-matter interaction at the quantum level.This is relevant for the study of fundamental quantum phenomena, the generation of artificial quantum systems, and for quantum information applications.In particular, it has been possible to considerably increase the intensity of light-matter interaction and to shape the coupling of quantum systems to the environment, so to realise unconventional and highly nonclassical states.However, in order to exploit these quantum states for technological applications, the question of how to measure and control these systems is crucial.Our work is focused on proposing and exploring new protocols for the measurement and the control of quantum systems, in which strong interactions and peculiar symmetries lead to the generation of highly nonclassical states.The first situation that we consider is the ultrastrong coupling regime in cavity (circuit) quantum electrodynamics.In this regime, it becomes energetically favourable to have photons and atomic excitations in the ground state, that is no more represented by the standard vacuum.In particular, in case of parity symmetry, the ground state is given by a light-matter Schrödinger cat state.However, according to energy conservation, the photons contained in these exotic vacua are bound to the cavity, and cannot be emitted into the environment.This means that we can not explore and control them by simple photodetection.In our work we propose a protocol that is especially designed to overcome this issue.We show that we can infer the photonic properties of the ground state from the Lamb shift of an ancillary two-level system.Another class of systems in which the fundamental parity symmetry leads to very unconventional quantum states is given by two-photon driven-dissipative resonators.Thanks to the reservoir engineering, it is today possible to shape the interaction with the environment to stabilize the system in particularly interesting quantum states.When a resonator (an optical cavity) exchanges with the environment by pairs of photons, it has been possible to observe the presence of optical Schrödinger cat states in the transient dynamics of the system.However, the quantum correlations of these states quickly decays due to the unavoidable presence of one-photon dissipation.Protecting the system against this perturbation is the goal of the parity triggered feedback protocol that we present in this thesis
Chia, Andy. "Explorations in Quantum Measurement and Control." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366552.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
Full Text
Thomsen, Laura Kathrine Wehde, and n/a. "Using Quantum Feedback to Control Nonclassical Correlations in Light and Atoms." Griffith University. School of Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040406.124012.
Full textThomsen, Laura Kathrine Wehde. "Using Quantum Feedback to Control Nonclassical Correlations in Light and Atoms." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367297.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Science
Full Text
Zhang, Zhigang. "Modeling, analysis and control of quantum electronic devices." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1811.
Full textLiang, Weichao. "Feedback exponential stabilization of open quantum systems undergoing continuous-time measurements." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS391.
Full textIn this thesis, we focus on the feedback stabilization of open quantum systems undergoing imperfect continuous-time measurements. First, we introduce the quantum filtering theory to obtain the time evolution of the conditional density operator representing a quantum state in interaction with an environment. This is described by a matrix-valued stochastic differential equation. Second, we study the asymptotic behavior of quantum trajectories associated with N-level quantum spin systems for given initial states, for the cases with and without feedback law. For the case without feedback, we show the exponential quantum state reduction. Then, we provide sufficient conditions on the feedback control law ensuring almost sure exponential convergence to a predetermined pure state corresponding to an eigenvector of the measurement operator. Third, we study the asymptotic behavior of trajectories of open multi-qubit systems for given initial states. For the case without feedback, we show the exponential quantum state reduction for N-qubit systems with two quantum channels. Then, we focus on the two-qubit systems, and provide sufficient conditions on the feedback control law ensuring asymptotic convergence to a target Bell state with one quantum channel, and almost sure exponential convergence to a target Bell state with two quantum channels. Next, we investigate the asymptotic behavior of trajectories of open quantum spin-1/2 systems with unknown initial states undergoing imperfect continuous-time measurements, and provide sufficient conditions on the controller to guarantee the convergence of the estimated state towards the actual quantum state when time goes to infinity. Finally, we discuss heuristically the exponential stabilization problem for N-level quantum spin systems with unknown initial states and propose candidate feedback laws to stabilize exponentially the system
Wyngaard, Adrian Leigh. "Saturated absorption spectroscopy of rubidium and feedback control of LASER frequency for Doppler cooling." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2621.
Full textThis research investigates the absorption spectra of rubidium and the feedback control of an external cavity diode laser. This research is a necessary prerequisite for laser (Doppler) cooling and trapping of rubidium atoms. Cooling rubidium atoms down to such low temperatures can be achieved using the Doppler cooling technique. Here a laser is tuned to remain resonant with a speci c atomic transition. To do this, the absorption spectra of rubidium must therefore be observed. All of the above require a reasonable knowledge about topics such as atomic physics, laser cooling and trapping, feedback control systems, and absorption spectroscopy. A discussion of these topics is provided. We have utilised an experimental setup which allowed for measurements of the Doppler broadened and Doppler free absorption spectra of rubidium, as well the analysis of the Zeeman e ect on the Doppler free spectra. The setup consisted of a saturated absorption spectrometer for high resolution spectroscopy and a Michelson interferometer for calibrating our measurements. In analysing the Zeeman e ect we added a set of Helmholtz coils to the saturated absorption spectroscopy arrangement to measure the splitting of the hyper ne energy levels.
French South African Institute of Technology (F'SATI) National Research Foundation
Alonso, Castaneda Jose Joaquin [Verfasser], and Eric [Gutachter] Lutz. "Thermodynamics along classical and quantum trajectories under feedback control / Jose Joaquin Alonso Castaneda ; Gutachter: Eric Lutz." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1150964367/34.
Full textBlanchard, Romain. "Fourier optics for wavefront engineering and wavelength control of lasers." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11216.
Full textEngineering and Applied Sciences
Mosshammer, Klemens [Verfasser], Tobias [Akademischer Betreuer] Brandes, Coello Gloria [Akademischer Betreuer] Platero, and Otto [Akademischer Betreuer] Dopfer. "Semiclassical spin dynamics and feedback control in quantum transport / Klemens Mosshammer. Gutachter: Tobias Brandes ; Gloria Platero Coello ; Otto Dopfer. Betreuer: Tobias Brandes." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/107580745X/34.
Full textLeghtas, Zaki. "Préparation et stabilisation de systèmes quantiques." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00740115.
Full textGoh, Matthew. "Feedback control of atomic Fermi gases." Thesis, 2019. http://hdl.handle.net/1885/202032.
Full textWang, Shi. "Mixed quantum-classical linear systems synthesis and quantum feedback control designs." Phd thesis, 2014. http://hdl.handle.net/1885/151564.
Full textWu, Po-Yi, and 吳柏儀. "Optimal Output Feedback Control of the Quantum System." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/86215541191851087576.
Full text中原大學
機械工程學系
88
The objective of this paper is to develop the optimal output feedback control theory for the quantum system, which is regarded as a bilinear system. The successive approximation procedure is employed for this optimal control problem. Main characteristic of the output feedback method is that the control input can be directly obtained from the detected outputs that record the system responses. The proposed control method is applied to transfer different states of hydrogen fluoride (HF) molecule, which is modeled as an oscillator interacting with a laser field via electric dipole moment. Finally, numerical results including the probabilities of vibrational states, the optimized laser field amplitude, the total energy and the dissociation yield are provided to validate the theoretical results.
Liang, Tsay Dong, and 蔡棟良. "A feedback control of a quantum well laser diode." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/10144578856942565509.
Full text國立交通大學
應用數學系
87
Electronic-controlled route to chaos in a laser diode is further improved by a feedback control technique. By introducing an extra feedback control term cS (t- ), chaotic light output can be achieved by tuning the parameter c without changing the input signal and the bias current. In chaotic region, the power spectra of the photon density shows a broad continuous component and indicates chaotic vibrations in the laser diode. This approach offers an external-controllable chaotic light source for possible digital communication and cryptographic applications.
Huang, Shang-Yu, and 黃上瑜. "Theoretical Study of Quantum Feedback andQuantum Optimal Control for Superconducting Qubits." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73601137811516449853.
Full text國立臺灣大學
物理研究所
102
An essential prerequisite for quantum information processing (QIP) is precise coherent control of the dynamics of quantum systems or quantum bits (qubits). This thesis is devoted to the study of quantum control and manipulation of superconducting qubits that are promising candidates for scalable solid-state quantum computing. We study two different types of superconducting qubits and architectures: Circuit cavity quantum electrodynamics (QED) and coupled flux qubit systems. In the first part, we present a simple and promising quantum feedback control scheme for deterministic generation and stabilization of a three-qubit entangled W state in the superconducting circuit QED system. We simulate the dynamics of the proposed quantum feedback control scheme using the quantum trajectory approach with an effective stochastic maser equation obtained by a polaron-type transformation method and demonstrate that in the presence of moderate environmental decoherence, the average state fidelity higher than 0.9 can be achieved and maintained for a considerably long time (much longer than the single-qubit decoherence time). This control scheme is also shown to be robust against measurement inefficiency and individual qubit decay rate differences. Finally, the comparison of the polaron-type transformation method to the commonly used adiabatic elimination method to eliminate the cavity mode is presented. In the second part, we apply the quantum optimal control theory based on the Krotov method to implement single-qubit X and Z gates and two-qubit CNOT gates for inductively coupled superconducting flux qubits with fixed qubit transition frequencies and fixed off-diagonal qubit-qubit coupling. The qubits in our scheme are operated at the optimal coherence points and the gate operation times (single-qubit gates <1 ns; CNOT gates 2 ns) are much shorter than the corresponding qubit decoherence time. A CNOT gate or other general quantum gates can be implemented in a ingle run of pulse sequence rather than being decomposed into several single-qubit and some entangled two-qubit operations in series by composite pulse sequences. Quantum gates constructed via our scheme are all with very high delity (very low error) as our optimal control scheme takes into account the fixed qubit detuning and fixed two- qubit interaction as well as all other time-dependent magnetic-eld-induced single- qubit interactions and two-qubit ouplings. In addition, we also investigate the effects of inefficient measurement and additional decoherence on the problems of nonadiabatic elimination of an auxiliary mode coupled to the system of interest in continuous quantum measurements. In contrast to the adiabatic elimination method, the eveloped nonadiabatic elimination approach is particularly important when the eliminated auxiliary mode evolves at a time scale larger than or comparable to the typical system evolution or decay time scale as, in this case, the auxiliary mode has finite memory, and the resultant dynamics of the system alone becomes non-Markovian. We investigate an exactly solvable model of an optomechanical system with a linear interaction with an auxiliary cavity mode to illustrate our approach.
Pei, Shi-Jai, and 裴希佳. "A Quantum Particle Swarm Optimization Algorithm for Feedback Control of Semi-Autonomous Driver Assistance Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/63112024437431674453.
Full text國立中興大學
電機工程學系所
99
With the aging of the population, the development of automotive technology has become increasingly important for preventing car accident caused by senior drivers. As a basic research of driver assistance system for senior drivers, we propose a novel control design method for steering support. In this method, we consider the stability and limitation of a system, so that senior drivers can driver more safely and comfortably. In the context, we first use a particle swarm optimization (PSO) based method to search the optimal feedback gain under constraints for achieving tracking control. To reduce the convergence time further, the particle swarm optimization algorithm is combined with quantum computing for the purpose. First we use the quantum bit to encode particle position, and use the quantum rotation gate to search the best particle position. Then we use the quantum NOT gate to avoid the premature convergence. Finally, in order to support the system requirements, we design the fitness function for the algorithm that can find the best feedback gains in the shortest time. Simulations and experimental results indicate that the proposed feedback controller based on the quantum particle swarm optimization (QPSO) is capable of providing satisfactory computational performance for the trajectory tracking and stabilization.