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Zenith Grant Awardee

Gheorghe Paraoanu

Aalto University

Project Title


Project Summary

The 20th century has produced two great theories in physics: the theory of relativity and quantum physics. Apparently, the two theories use a completely different set of conceptual tools. The spacetime manifold, the metric, the curvature, which are central to general relativity, play a rather marginal role in standard quantum physics, while the entire structure of Hilbert spaces, superpositions, entanglement, quantum-mechanical probabilities is almost directly at odds with the classical character of the theory of gravitation. Little overlap exists also in the domain where these theories have been tested: general relativity is used for astronomical distances, while quantum mechanics for the atomic scale and below. Can we bring these two theories in the same \'arena\' and see them confront each other? In this project the aim is to make the first steps towards creating an experimental platform, based on superconducting circuits, where the predictions of quantum physics and general relativity can be tested against each other. The \'referee\' of this confrontation is the concept of information – which has been recognized in recent times as playing an important role in both theories.

Technical Abstract

Information has emerged in the last years as a concept essential both in quantum theory and in gravitation. In both theories this concept can be put at the center stage, allowing us to pinpoint in a clear way the tension between the two theories. However, the experimental exploration of this tension is hampered by the difficulty of finding a common range of scales where both gravitation and quantum physics have manifest effects detectable by present measurement techniques. A lot of effort has been devoted to bringing up the quantumness to macroscopic scales: interference experiments with large molecules, and proposed experiments with large macroscopic mirrors or trapped dielectric particles are hoped to set the limits of validity of quantum mechanics in the macroscopic world of classical spacetime and gravitation. In this project I will turn the tables around – we will build an artificial spacetime background around a quantum object. This can be realized with quantum-coherent superconducting circuits, a field in which there has been a lot of progress in the last years. The quantum object will be an artificial atom – a transmon qubit – which will be embedded in a designed spacetime emulated by an array of SQUIDs.

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