Lecturer: Mr. Elisha Svetitsky
Affiliation: Racah Institute of Physics,
The Hebrew University of Jerusalem
Abstract:
Multi-level control of quantum
coherence exponentially reduces
communication and computation
resources required for a variety of
applications of quantum information
science. However, it also introduces
complex dynamics to be understood
and controlled. These dynamics can
be simplified and made intuitive by
employing group theory to visualize
certain four-level dynamics in a ‘Bell
frame’ comprising an effective pair of
uncoupled two-level qubits. We
demonstrate control of a Josephson
phase qudit with a single multi-tone
excitation, achieving successive
population inversions between the first
and third levels and highlighting
constraints imposed by the two-qubit
representation. Furthermore, the finite
anharmonicity of our system results in
a rich dynamical evolution, where the
two Bell-frame qubits undergo
entangling–disentangling oscillations
in time, explained by a Cartan gate
decomposition representation. The
Bell frame constitutes a promising tool
for control of multi-level quantum
systems, providing an intuitive clarity
to complex dynamics.
Reference: Nature Communications 5,
5617 (2014)