Type of Document Dissertation Author McCracken, Steven Blane URN etd-06062012-153941 Title Advances in Quantum Optical Metrology and the Establishment of an Invisible Quantum Tripwire Degree Doctor of Philosophy (Ph.D.) Department Physics & Astronomy Advisory Committee
Advisor Name Title Lee, Hwang Committee Chair Baldridge, Scott Committee Member Dowling, Jon Committee Member Johnson, Warren Committee Member Veronis, Georgios Committee Member Keywords
Date of Defense 2012-05-09 Availability unrestricted AbstractThis thesis presents a summary of the foundation and background of the field of quantum optics, and an analysis of some recent discoveries in various fields of which I have aided in furthering investigative research and advancement through publications. Such topics include numerical optimization of generalized quantum states used in phase sensitive quantum metrology, an analysis of object detection through the use of quantum interferometry in the presence of lossy conditions, and the use of the latter technique to propose an invisible quantum tripwire.
First is a collaborative effort to numerically optimize quantum optical states for quantum metrological applications. We optimize two-mode, entangled, number states of light in the presence of loss in order to maximize the Fisher information, which is equivalent to minimizing the phase uncertainty. We find that in the limit of zero loss the optimal state is the so-called N00N state, for small loss, the optimal state gradually deviates from the N00N state, and in the limit of large loss the optimal state converges to a generalized two-mode coherent state, with a finite total number of photons. The results provide a general protocol for optimizing the performance of a quantum optical interferometer in the presence of photon loss.
The next topic is statistical hypothesis testing of interaction free measurement and a quantitative limit on the obtainable error. Previous analyses have been based solely on detection probabilities known only in the infinite photon limit. Our analysis assumes a finite number of photons, and an investigation of reliability in the presence of photon loss and phase fluctuations. We use symmetric hypothesis testing and the Chernoff bound to provide error estimation after N independent, single photon trials.
Finally, we present a quantum optical interrogation technique capable of detecting an intrusion with very low probability of the quantum “tripwire” being revealed to the intruder. The tripwire exploits a curious nonlinear behavior of the quantum Zeno effect we discovered, which occurs in a lossy system. We also employ statistical hypothesis testing, allowing us to calculate a confidence level of interaction-free measurement after a given number of trials.
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