Abstract:
The time needed by a quantum system to reach a state fully distinguishable from the original
one provides a natural way of determining how fast the corresponding dynamical evolution is. This
orthogonality time admits a lower bound, expressible in terms of the energy’s expectation value
and the energy’s standard deviation, that yields a “quantum speed limit”. Composite quantum
systems need entanglement in order to achieve this limit. So far, most studies on the connection
between entanglement and the quantum speed limit have focused on the case of non-interacting
systems. The connection between quantum speed and entanglement is systematically investigated
here for the case of a system of two interacting qubits, taking into consideration all possible initial
states that evolve into an orthogonal one.
