Theoretical Physics

28 February 2014
Time: 12:00 to 01:00
Location: EC Stoner SR 8.60

Bruno Sanguinetti (Geneva, Switzerland)

Can one see entanglement? How a fun question stimulates serious physics.

Entanglement is one of the most fascinating aspects of quantum mechanics as it is far removed from our everyday sensory experience. It is an interesting question to see whether this is a fundamental limitation of our senses, or whether experiments can be designed to bring us closer to the quantum world. To answer this question we consider what is probably the most sensitive Human “measurement device”: the eye, capable of seeing a number of photons as low as 100. It has been shown that macroscopic superpositions of this size can be in principle achieved by strongly amplifying (cloning) a photon from an entangled pair. In this talk I will show how this experiment gives us insights into what entanglement might look like at macroscopic scales, and into the issues of realising and detecting such a state. These insights into the quantum-to-classical transition, have lead to a number of applications, such as the realisation of a primary standard of spectral radiance for telecommunication systems, and a light source and power meter with a long term stability greater than one part per million. I will conclude by describing how, in turn, the extreme precision of these devices will allow us to  explore new physics.



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