Entanglement of two superconducting qubits in a waveguide cavity via monochromatic two-photon excitation.
We report a system where fixed interactions between noncomputational levels make bright the otherwise forbidden two-photon |00}→|11} transition. The system is formed by hand selection and assembly of two discrete component transmon-style superconducting qubits inside a rectangular microwave cavity. The application of a monochromatic drive tuned to this transition induces two-photon Rabi-like oscillations between the ground and doubly excited states via the Bell basis. The system therefore allows all-microwave two-qubit universal control with the same techniques and hardware required for single qubit control. We report Ramsey-like and spin echo sequences with the generated Bell states, and measure a two-qubit gate fidelity of F(g)=90% (unconstrained) and 86% (maximum likelihood estimator).
IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA.
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S
Poletto
Jay M
JM
Gambetta
Seth T
ST
Merkel
John A
JA
Smolin
Jerry M
JM
Chow
A D
AD
Córcoles
George A
GA
Keefe
Mary B
MB
Rothwell
J R
JR
Rozen
D W
DW
Abraham
Chad
C
Rigetti
M
M
Steffen