16 research outputs found
Quantum Optical Metrology, Sensing and Imaging
In this dissertation we begin with a brief introduction to quantum optics concentrating on the topics of the noise of quantum optical states, quantum estimation theory, quantum interferometry and the atom-field interaction. This background is necessary for understanding the discussions in later chapters. In particular, quantum interferometry, which is optical interferometry when the light source is a quantum mechanical state, plays a central role in this dissertation. In Chapter 2 we discuss the phase estimation sensitivity of quantum metrology when photon loss is present. In Chapter 3 we extend the discussion to include the phase fluctuation of the system caused by the environment. We model our metrological system with the Mach-Zehnder interferometer (MZI) and use a light field in the symmetric number-path entangled state as the source. In both chapters we use the parity operator as the detection scheme and show that it is optimal under pure dephasing. In Chapter 4 we discuss the application of quantum optical states in remote sensing and propose a new scheme for a quantum radar. Again, our scheme consists of a MZI and a coherent light source. It is shown that using only coherent states of light and quantum homodyne detection, super-resolving ranging and angle determination are achievable. Chapter 5 is devoted to the generation of a super-resolving single-photon number-path entangled state which may serve as a proof-of-principle prototype for quantum lithography. The repeated implementation of MZIs is shown to be able to remove photons coherently from both modes of a symmetric number-path entangled state with arbitrarily high photon number. Lastly, in Chapter 6 we introduce the phenomenon known as polarization self-rotation and discuss its potential in generating a squeezed vacuum state, which has a huge impact in quantum interferometry
Automatic Seismic Salt Interpretation with Deep Convolutional Neural Networks
One of the most crucial tasks in seismic reflection imaging is to identify
the salt bodies with high precision. Traditionally, this is accomplished by
visually picking the salt/sediment boundaries, which requires a great amount of
manual work and may introduce systematic bias. With recent progress of deep
learning algorithm and growing computational power, a great deal of efforts
have been made to replace human effort with machine power in salt body
interpretation. Currently, the method of Convolutional neural networks (CNN) is
revolutionizing the computer vision field and has been a hot topic in the image
analysis. In this paper, the benefits of CNN-based classification are
demonstrated by using a state-of-art network structure U-Net, along with the
residual learning framework ResNet, to delineate salt body with high precision.
Network adjustments, including the Exponential Linear Units (ELU) activation
function, the Lov\'{a}sz-Softmax loss function, and stratified -fold
cross-validation, have been deployed to further improve the prediction
accuracy. The preliminary result using SEG Advanced Modeling (SEAM) data shows
good agreement between the predicted salt body and manually interpreted salt
body, especially in areas with weak reflections. This indicates the great
potential of applying CNN for salt-related interpretations.Comment: 11 pages, 7 figure
Super-Resolving Quantum Radar: Coherent-State Sources with Homodyne Detection Suffice to Beat the Diffraction Limit
There has been much recent interest in quantum metrology for applications to
sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum
radar, atmospheric absorption and diffraction rapidly degrades any actively
transmitted quantum states of light, such as N00N states, so that for this
high-loss regime the optimal strategy is to transmit coherent states of light,
which suffer no worse loss than the linear Beer's law for classical radar
attenuation, and which provide sensitivity at the shot-noise limit in the
returned power. We show that coherent radar radiation sources, coupled with a
quantum homodyne detection scheme, provide both longitudinal and angular
super-resolution much below the Rayleigh diffraction limit, with sensitivity at
shot-noise in terms of the detected photon power. Our approach provides a
template for the development of a complete super-resolving quantum radar system
with currently available technology.Comment: 23 pages, content is identical to published versio
Strategies for choosing path-entangled number states for optimal robust quantum optical metrology in the presence of loss
To acquire the best path-entangled photon Fock states for robust quantum
optical metrology with parity detection, we calculate phase information from a
lossy interferometer by using twin entangled Fock states. We show that (a) when
loss is less than 50% twin entangled Fock states with large photon number
difference give higher visibility while when loss is higher than 50% the ones
with less photon number difference give higher visibility; (b) twin entangled
Fock states with large photon number difference give sub-shot-noise limit
sensitivity for phase detection in a lossy environment. This result provides a
reference on what particular path-entangled Fock states are useful for real
world metrology applications
Machine Learning for Prediction of Sudden Cardiac Death in Heart Failure Patients With Low Left Ventricular Ejection Fraction: Study Protocol for a Retrospective Multicentre Registry in China
Introduction: Left ventricular ejection fraction (LVEF) ≤35%, as current significant implantable cardioverter-defibrillator (ICD) indication for primary prevention of sudden cardiac death (SCD) in heart failure (HF) patients, has been widely recognised to be inefficient. Improvement of patient selection for low LVEF (≤35%) is needed to optimise deployment of ICD. Most of the existing prediction models are not appropriate to identify ICD candidates at high risk of SCD in HF patients with low LVEF. Compared with traditional statistical analysis, machine learning (ML) can employ computer algorithms to identify patterns in large datasets, analyse rules automatically and build both linear and non-linear models in order to make data-driven predictions. This study is aimed to develop and validate new models using ML to improve the prediction of SCD in HF patients with low LVEF. Methods and analysis: We will conduct a retroprospective, multicentre, observational registry of Chinese HF patients with low LVEF. The HF patients with LVEF ≤35% after optimised medication at least 3 months will be enrolled in this study. The primary endpoints are all-cause death and SCD. The secondary endpoints are malignant arrhythmia, sudden cardiac arrest, cardiopulmonary resuscitation and rehospitalisation due to HF. The baseline demographic, clinical, biological, electrophysiological, social and psychological variables will be collected. Both ML and traditional multivariable Cox proportional hazards regression models will be developed and compared in the prediction of SCD. Moreover, the ML model will be validated in a prospective study. Ethics and dissemination: The study protocol has been approved by the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (2017-SR-06). All results of this study will be published in international peer-reviewed journals and presented at relevant conferences