Z-Gate Operation on a Superconducting Flux Qubit via its Readout SQUID
Journal article, 2015

Detuning a superconducting qubit from its rotating frame is one means to implement a Z-gate operation. In this work, we implement a Z gate by pulsing a current through the qubit’s readout dc SQUID. While the dc SQUID acts as a magnetic flux sensor for qubit readout, we in turn may use it as a flux actuator with tunable strength to impose a qubit frequency shift. Using this approach, we demonstrate Ramsey-type free-induction experiments with time constants as long as 280 ns and rotation frequencies as high as 1.4 GHz. We experimentally demonstrate an inferred Z-gate fidelity of approximately 90%, limited largely by the bandwidth of our system. In the absence of this limitation, we argue that the inferred fidelity may be improved to as high as 99%.

superconducting qubits

quantum control

Author

Jonas Bylander

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Physical Review Applied

2331-7019 (eISSN)

Vol. 3 034004-

Areas of Advance

Nanoscience and Nanotechnology

Subject Categories

Nano Technology

Condensed Matter Physics

DOI

10.1103/PhysRevApplied.3.034004