Method for direct observation of coherent quantum oscillations in a superconducting phase qubit. Computer simulations

TL;DR

This paper proposes a method for directly observing Rabi oscillations in a superconducting phase qubit using a resonant tank circuit, supported by computer simulations demonstrating detectability with standard NMR techniques.

Contribution

It introduces a novel approach for direct measurement of quantum oscillations in superconducting qubits via a coupled tank circuit, including detailed simulation analysis.

Findings

Rabi oscillations in MHz range can be detected.

The method accounts for back action and measurement unpredictability.

Simulations show feasibility with conventional NMR techniques.

Abstract

Time-domain observations of coherent oscillations between quantum states in mesoscopic superconducting systems have so far been restricted to restoring the time-dependent probability distribution from the readout statistics. We propose a method for direct observation of Rabi oscillations in a phase qubit. The external source, typically in GHz range, induces transitions between the qubit levels. The resulting Rabi oscillations of supercurrent in the qubit loop are detected by a high quality resonant tank circuit, inductively coupled to the phase qubit. Here we present the results of detailed computer simulations of the interaction of a classical object (resonant tank circuit) with a quantum object (phase qubit). We explicitly account for the back action of a tank circuit and for the unpredictable nature of outcome of a single measurement. According to the results of our simulations the Rabi oscillations in MHz range can be detected using conventional NMR pulse Fourier technique.