Strong coupling of a quantum oscillator to a flux qubit at its symmetry point.
A flux qubit biased at its symmetry point shows a minimum in the energy splitting (the gap), providing protection against flux noise. We have fabricated a qubit of which the gap can be tuned fast and have coupled this qubit strongly to an LC oscillator. We show full spectroscopy of the qubit-oscillator system and generate vacuum Rabi oscillations. When the gap is made equal to the oscillator frequency ν(osc) we find the largest vacuum Rabi splitting of ∼0.1 ν(osc). Here being at resonance coincides with the optimal coherence of the symmetry point.
Fedorov
A
A
Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands. fedoroar@phys.ethz.ch
Feofanov
A K
AK
Macha
P
P
Forn-Díaz
P
P
Harmans
C J P M
CJ
Mooij
J E
JE