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ESE Seminar: “Quantum information processing with superconducting circuits: Purcell effect and the measurement problem”

February 25, 2020 at 11:00 AM - 12:00 PM

With recent advances in state preparation, gate, and measurement operations, superconducting circuit architectures are now leading candidates for quantum information processing. As micro-fabricated circuits are scaled up towards a practical quantum processor, strict requirements on the fidelity of operations required for quantum computation are imposed. For theorists, this mandates the development of accurate models describing the dynamics of complex superconducting circuits subject to strong drives.

This talk will begin with an elementary introduction to such systems and their description in terms of quantum electrodynamics, the fundamental theory of light-matter interactions. We will then address the problem of the Purcell effect, which is the enhancement of the decay rate of a single qubit due to a linear electromagnetic environment, and show how convergent results can be obtained without any artificial high-frequency cutoffs. We will also explain how the Purcell rate is further enhanced in the presence of the drive fields typically used to measure qubits, which is a ubiquitous problem encountered in present-day experiments.

Alexandru Petrescu

Institut Quantique Fellow, Université de Sherbrooke

I am presently an Institut Quantique fellow at the Université de Sherbrooke, and previously I completed a postdoctoral appointment in the theoretical quantum optics group of Prof. Hakan Türeci at Princeton University working primarily on superconducting circuit quantum electrodynamics. Prior to that, I defended my PhD in condensed matter theory on August 27th 2015 and obtained a degree from the École Polytechnique, CPHT and Yale University, supervised by Prof. Karyn Le Hur and co-supervised by Prof. S. M. Girvin. My thesis jury was composed of Profs. S. M. Girvin (president of thesis committee), R. Shankar (member), Liang Jiang (member), David DeMille (member), and Eugene Demler of Harvard University as external reader. My PhD dealt with strongly interacting phases of bosons in bandstructures described by topological invariants, and the emergent many-body ground states. Before this, I obtained my Bachelor’s diploma from Princeton in 2009, with a thesis in experimental particle physics


Electrical and Systems Engineering
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