  Electrostatically defined quantum dots in bilayer graphene offer a promising
platform for spin qubits with presumably long coherence times due to low
spin-orbit coupling and low nuclear spin density. We demonstrate two different
experimental approaches to measure the decay times of excited states. The first
is based on direct current measurements through the quantum device. Pulse
sequences are applied to control the occupation of ground and excited states.
We observe a lower bound for the excited state decay on the order of hundred
microseconds. The second approach employs a capacitively coupled charge sensor
to study the time dynamics of the excited state using the Elzerman technique.
We find that the relaxation time of the excited state is of the order of
milliseconds. We perform single-shot readout of our two-level system with a
visibility of $87.1\%$, which is an important step for developing a quantum
information processor in graphene.
