Decoherence and Time-Resolved Readout in Superconducting Quantum Circuits (Dekohärenz und zeitaufgelösste Quantenmessung in supraleitenden Schaltkreisen)
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Beschreibung
Superconducting quantum circuits are promising candidates for solid-state based quantum computation. However, minimizing dissipation caused by external noise sources remains a tough challenge. Here, we present an analytic dissipative theory for a complex circuit of two resonators coupled via a flux qubit. In this 'quantum switch', the qubit acts as a tunable coupler between the resonators, which enables switching their interaction on and off. A natural application of this setup is to create entangled two-resonator states. However, it turns out that, even if the qubit has no dynamics, qubit dissipation affects the resonators to a considerable degree.
For successful quantum information processing, it is desirable to demonstrate the coherence of qubit time evolution in single-shot experiments without too much backaction on the qubit. In the second part of this thesis, we present a novel scheme for a time-resolved single-run measurement of coherent qubit dynamics. For a charge qubit probed by a weak high-frequency signal, we find that the reflected outgoing signal possesses a time-dependent phase shift that is proportional to a qubit observable. A similar approach is presented for a flux qubit coupled to a resonantly driven high-frequency oscillator, which serves as a meter device for monitoring the time-resolved qubit dynamics.
Autor*in
Georg M. Reuther
Themen in »Decoherence and Time-Resolved Readout in Superconducting Quantum Circuits (Dekohärenz und zeitaufgelösste Quantenmessung in supraleitenden Schaltkreisen)«
dissipative quantum systems / dissipative Quantensysteme quantum electrodynamics / Quantenelektrodynamik quantum information / Quanteninformation quantum measurement / Quantenmessung superconducting quantum circuits / supraleitende Schaltkreise