Quantum Mechanics seminars

Sisi Zhou examines how quantum information methods can improve the precision of physical measurements. Qubit examples distinguish noise that quantum error correction can suppress from noise indistinguishable from the signal. The discussion extends to several qubits, phase estimation, many-body measurements and distributed sensors. A second part applies quantum-learning tools, including tomography, certification and purification, to estimation of several parameters. Because incompatible observables prevent all parameters from being measured optimally together, designing measurements is difficult. The talk presents practical protocols for several such sensing tasks that combine efficient implementation with sensitivity close to the optimum.

Alain Aspect, John Clauser and Anton Zeilinger describe how questions about the foundations of quantum mechanics became experimentally testable and technologically productive. The lectures connect Bell’s inequalities with measurements of correlations between entangled photons, explaining how experiments discriminate between quantum predictions and local hidden-variable descriptions. Clauser and Aspect discuss the development of tests and the importance of their experimental assumptions and loopholes. Zeilinger develops the use of entanglement as a resource, including experiments on quantum teleportation and information processing. The programme follows the path from foundational doubts to controlled manipulation of quantum states, bringing together conceptual questions, experimental design and the origins of quantum information science.

Agent-causal libertarian free will asserts that the conscious agent is the ultimate cause of her own voluntary behavior. A major reason to reject libertarian free will is that it seems incompatible with our current knowledge of physics. In this talk I will argue how quantum processes, specifically non-random collapses of the wavefunction in the human cortex, may enable libertarian free will. I will discuss how this account can be empirically tested.

Aram Harrow connects the Unique Games conjecture, especially small-set expansion, with the quantum separability problem. The Lasserre hierarchy used for Unique Games and the k-extendible relaxation of quantum separability turn out to be closely equivalent algorithmic approaches. The talk examines how quantum-information conjectures could yield quasipolynomial algorithms or hardness results for Unique Games, and discusses promising research directions. It introduces the necessary quantum mechanics, Unique Games, and hierarchy background rather than presupposing it. The presentation draws partly on the papers arXiv:1205.4484 and arXiv:1210.6367.