Quantum Measurement Theory Applied to Cold Atoms

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My research concerns the theory of cold atoms, which are atoms that have been cooled down to temperatures below one millionth of one degree above absolute zero. Cold atoms have remarkable properties: at such low temperatures they behave like waves (wave-particle duality) and can form new states of matter such as Bose-Einstein condensates (BECs) where all the atoms share exactly the same quantum state and form giant macroscopic matter waves - the tsunamis of the quantum world. This means that quantum phenomena that are normally confined to microscopic scales become amplified up to macroscopic ones. With this Discovery grant I propose to use cold atoms to try to resolve the paradox as to why we do not normally see the interference of quantum waves in our macroscopic world. This is known as the quantum measurement problem, and I plan to study it in BECs that are held in two spatially separated traps, so that, according to quantum mechanics, each atom is in two places at once! This work has technological implications: devices currently under intensive development, such as quantum computers, need to maintain quantum interference in the face of the deleterious effects of a thermal environment, and cold atoms make very versatile test-beds for quantum control techniques which attempt to counteract these thermal effects.