Atoms, lasers and qubits  

#### Prerequisites * Foundations of Physics 3A (PHYS3621). #### Corequisites * None. #### Excluded Combination of Modules * None. #### Aims * This module is designed primarily for students studying Department of Physics or Natural Sciences degree programmes. * It builds on the Level 3 module Foundations of Physics 3A (PHYS3621) and provides a working knowledge of lasers and the physics of quantum computation at an advanced level appropriate to Level 4 physics students. #### Content * The syllabus contains: * Laser Physics: Definition of a laser. Atom-light interactions. Absorption, spontaneous and stimulated emission. Line broadening mechanisms and emission linewidth. Population inversion and gain. Laser oscillator: cavity basics and threshold; gain saturation and output power. Population inversion in 3 and 4-level systems. Laser pumping with case studies of specific laser systems. Cavity modes and cavity stability. Gaussian beams. Cavity effects: single frequency operation. Cavity effects: Q switching and mode locking. Laser spectroscopy and optical frequency combs. Case studies of laser applications. * Quantum Information and Computing: Manipulation of qubits: Limits of classical computing. Feynman’s insight. Quantum mechanics revision. Projection operators. Pauli matrices. Single-qubit operations: Resonant field, the Rabi solution. The Bloch sphere. The Ramsey technique. Two-qubit states. Tensor products. Correlations. Entanglement. Bell states. Two-qubit gates. The CNOT gate. Physical Realizations: The DiVincenzo criteria. Controlling the centre-of mass motion of atoms – laser cooling. Controlling the internal states of atoms. Trapping and manipulating single atoms. Rydberg states. Decoherence. Case studies of contemporary Quantum Information Processing. #### Learning Outcomes Subject-specific Knowledge: * Having studied this module students will be aware of the principles of lasers and be able to describe the operation, design features and uses of various laser systems. * They will be familiar with the concept of the qubit and with the manipulation of qubits with electromagnetic fields, with many-qubit states, their correlation properties and the concept of entanglement, with quantum gates, quantum computing and the physical realization of these ideas. Subject-specific Skills: * In addition to the acquisition of subject knowledge, students will be able to apply knowledge of specialist topics in physics to the solution of advanced problems. * They will know how to produce a well-structured solution, with clearly-explained reasoning and appropriate presentation. Key Skills: #### Modes of Teaching, Learning and Assessment and how these contribute to the learning outcomes of the module * Teaching will be by lectures and workshops. * The lectures provide the means to give a concise, focused presentation of the subject matter of the module. * The lecture material will be explicitly linked to the contents of recommended textbooks for the module, thus making clear where students can begin private study. * When appropriate, lectures will also be supported by the distribution of written material, or by information and relevant links online. * Regular problem exercises and workshops will give students the chance to develop their theoretical understanding and problem solving skills. * Students will be able to obtain further help in their studies by approaching their lecturers, either after lectures or at mutually convenient times. * Student performance will be summatively assessed through an open-book examination and formatively assessed through problem exercises. * The open-book examination will provide the means for students to demonstrate the acquisition of subject knowledge and the development of their problem-solving skills. * The problem exercises provide opportunities for feedback, for students to gauge their progress and for staff to monitor progress throughout the duration of the module. More information at: https://apps.dur.ac.uk/faculty.handbook/2023/UG/module/PHYS4121
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Atoms, lasers and qubits
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